Coronavirus;

Why is Paxlovid (nirmatrelvir/ritonavir) a promising new drug in our fight against Covid-19?

FA Manian MD, MPH, , Leave a comment

Based on the manufacturer’s (Pfizer’s) report, there are several reasons why Paxlovid may be a promising drug:1

  • It’s the first oral drug approved by the FDA for Emergency Use Authorization (EUA)
  • It reduces risk of hospitalization or death by ~ 90% (when taken within 3-5 days of symptom onset) in patients at high risk of complications from Covid-19
  • It reduces viral load at day 5 of treatment by 10-fold compared to placebo, theoretically reducing infectivity at least in household settings 2
  • Serious adverse events were comparable to placebo; possible side effects include liver disease, diarrhea, altered sense of taste, hypertension and muscle aches
  • Nirmatrelvir component of Paxlovid has been found to be active against a variety of SARS-CoV-2 variants of concern such as alpha, beta, delta as well as the newer omicron variant. This finding is in contrast to significantly reduced or loss of neutralizing activity of many commercially-available monoclonal antibody products against the omicron variant (eg, Casirivimab/Imdevimab-REGEN-COV, Bamlanivimab/Etesevimab, but not Sotrovimab)  designed to reduce serious Covid-19 complications in mild to moderate disease. 3-4

Few caveats to keep in mind when prescribing Paxlovid at this time:

  • It’s only approved for adults and children 12 years of age or older weighing at least 88 lbs (40kg) who test positive for SARS-CoV-2
  • Patients should be at high risk for progression to severe Covid-19 such as hospitalization or death
  • Per manufacturer (Pfizer), Paxlovid should not be taken if a patient is on certain medications due to the possibility of adverse drug interactions. The list includes colchicine, lovastatin, simvastatin, sildenafil for pulmonary arterial hypertension, some anti-epileptics (eg, carbamazepine, phenytoin), rifampin and St. John’s Wort.
  • There is no experience with treating pregnant women or breastfeeding mothers.
  • Pfizer recommends effective barrier contraception or refraining from sexual activity while taking Paxlovid

Paxlovid comes in a box of blister packs containing 5 days’ worth of medications (two 150 mg tablets of nirmatrelvir plus one 100 mg tablet of ritonavir to be taken 2x/day).  

Bonus Pearl: Another preliminary study of Paxlovid, this time including unvaccinated adults at low risk of hospitalization or death, has found a 70% reduction in hospitalization and no death compared to placebo with marginal statistical significance (P=0.051) but still with a 10-fold drop in viral load. 1

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References

  1. Pfizer announces additional phase 2/3 study results confirming robust efficacy of novel COVID-19 oral antiviral treatment candidate in reducing risk of hospitalization or death. https://www.pfizer.com/news/press-release/press-release-detail/pfizer-announces-additional-phase-23-study-results . Accessed Dec 23, 2021.
  2. Marc A, kerioui M, Blanquart F, et. al. Quantifying the relationship between SARS-CoV-2 viral load and infectiousness. eLife 2021;10:e69302. https://elifesciences.org/articles/69302#:~:text=Based%20on%20the%20current%20knowledge,24%25%20to%2058%25%20in%20household  
  3. Aggarwal A, Stell AO, Walker G, et al. SARS-CoV-2 Omicron:evasion of potent humoral responses and resistance to clinical immunotherapeutics relative to viral variants of concern. MedRxiv 2021. Doi:https://doi.org/10.1101/2021.12.14.21267772. https://www.medrxiv.org/content/10.1101/2021.12.14.21267772v1
  4. Planas D, Saunders N, Maes P, et al. Considerable escape of SARS-CoV-2 variant Omicron to antibody neutralization. MedRxiv 2021. https://www.biorxiv.org/content/10.1101/2021.12.14.472630v1

Disclosures: The listed questions and answers are solely the responsibility of the author and do not necessarily represent the official views of Mercy Hospital-St. Louis, Massachusetts General Hospital, Harvard Catalyst, Harvard University, their affiliate academic healthcare centers, or its contributors. Although every effort has been made to provide accurate information, the author is far from being perfect. The reader is urged to verify the content of the material with other sources as deemed appropriate and exercise clinical judgment in the interpretation and application of the information provided herein. No responsibility for an adverse outcome or guarantees for a favorable clinical result is assumed by the author. Thank you!

Why is Paxlovid (nirmatrelvir/ritonavir) a promising new drug in our fight against Covid-19?

What’s the effectiveness of Covid-19 vaccination in patients with multiple sclerosis (MS) treated with high-efficacy disease-modifying therapies?

FA Manian MD, MPH, , , , , , , , , , , , , , , , Leave a comment

The answer appears to be dependent on which high-efficacy disease-modifying agent is being used to treat MS.  Limited data suggest that cladribine treatment does not impair humoral response to Covid-19 vaccine in patients with MS, while ocrelizumab and fingolimod have a major negative impact on vaccine responsiveness based on humoral antibody measurements.1

A study involving 125 Covid-19 MS vaccine (mRNA, Pfizer BNT162b2) recipients  (58% females, 61% relapse-remitting, 19% primary-progressive, 14% secondary-progressive, 3% clinically isolated syndrome and 2% radiologically isolated syndrome), found high levels of SARS-CoV-2 anti-spike IgG in all subjects (n=23) receiving cladribine as early as 4.4 months from last treatment dose.1

In contrast only 4% of patients with MS treated with fingolimod had a post-vaccination humoral response (time-interval from last treatment dose to vaccination not reported).  Similarly, most patients under treatment with ocrelizumab failed to develop a post-vaccination humoral response, with only 23% demonstrating a protective antibody titer (time-interval from last treatment dose 3.1-8.9 months).

These results may not be totally surprising given the attenuated humoral response to several common vaccines in patients with MS treated with ocrelizumab or fingolimod.2,3

Given the potential suboptimal response to Covid-19 vaccine in patients with MS treated with fingolimod or ocrelizumab, until further data become available, it’s fair to state that patients treated with these agents should NOT depend on vaccination to protect them from Covid-19 and that they may need to still take extra precautions during the pandemic.   

 

Bonus Pearl: Did you know that fingolimod prevents lymphocyte egression from secondary lymphoid tissue and ocrelizumab is an anti-CD20 monoclonal antibody that depletes B lymphocytes?1

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Reference

  1. Achiron A, Mandel M, Dreyer-Alster S, et al. Humoral immune response to COVID-19 mRNA vaccine in patients with multiple sclerosis treated with high-efficacy disease-modifying therapies. Therapeutic Adances in Neurological Disorders 2021;14:1-8. https://journals.sagepub.com/doi/full/10.1177/17562864211012835
  2. Bar-Or A, Calkwood JC, Chognot C, et al. Effect of ocrelizumab on vaccine responses in patients with multiple sclerosis. Neurology 2020; 95:e1999-22008. https://pubmed.ncbi.nlm.nih.gov/32727835/
  3. Kappos L, Mehling M, Arroyo R, et al. Randomized trial of vaccination in fingolimod-treated patients with multiple sclerosis. Neurology 2015;84:872-9. https://pubmed.ncbi.nlm.nih.gov/25636714/  

Disclosures: The listed questions and answers are solely the responsibility of the author and do not necessarily represent the official views of Mercy Hospital-St. Louis or its affiliate healthcare centers, Mass General Hospital, Harvard Medical School or its affiliated institutions. Although every effort has been made to provide accurate information, the author is far from being perfect. The reader is urged to verify the content of the material with other sources as deemed appropriate and exercise clinical judgment in the interpretation and application of the information provided herein. No responsibility for an adverse outcome or guarantees for a favorable clinical result is assumed by the author. Thank you!

What’s the effectiveness of Covid-19 vaccination in patients with multiple sclerosis (MS) treated with high-efficacy disease-modifying therapies?

Can Covid-19 exacerbate seizures in patients with epilepsy?

FA Manian MD, MPH, , , , , , , , , , , , , , Leave a comment

There have been several reports of seizure exacerbation in epileptic patients after Covid-19 infection. Seizure exacerbations have been observed in epileptic patients with uncontrolled epilepsy, as well as patients who were previously controlled with antiepileptic drugs (AEDs).1,2

In a survey of 362 epileptic patients in Wuhan, China, the site of the initial outbreak, 31 (8.6%) patients reported an increased number of seizures in the month after the public lockdown began; 16 (51.6%) of the 31 patients with seizure exacerbation had prior exposure to Covid-19.1

In a study of 439 patients with Covid-19 infection in Egypt, 19 (4.3%) patients presented with acute seizures.2  Two of the 19 seizure patients had a previous diagnosis of epilepsy, which had been controlled for up to 2 years. Interestingly, the other 17 patients had new onset seizures without a previous epilepsy diagnosis.

Covid-19 has been proposed to induce seizures by eliciting inflammatory cytokines in the central nervous system, leading to neuronal necrosis and increased glutamate levels in the cerebral cortex and hippocampus.3

Covid-19 infection may have also indirectly caused seizure exacerbations in a number of epileptic patients. Interestingly, stress related to worrying about the effect of the outbreak on a patient’s seizure activity was associated with seizure exacerbations (odds ratio: 2.5, 95% CI: 1.1-6.1)2. It is also possible that some seizure exacerbations may have been due to fear of visiting the hospital and AED withdrawal, as was demonstrated during the 2003 SARS outbreak.4

Bonus Pearl: Did you know that Guillain–Barré Syndrome has also been observed in patients with Covid-19 infection?5

Contributed by Luke Vest, Medical Student, St. Louis University Medical School

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References:

  1. Huang, S., Wu, C., Jia, Y., et al. (2020). COVID-19 outbreak: The impact of stress on seizures in patients with epilepsy. Epilepsia, 61(9), 1884-1893. https://doi.org/10.1111/epi.16635  
  2. Khedr, E. M., Shoyb, A., Mohammaden, M., & Saber, M. (2021). Acute symptomatic seizures and COVID-19: Hospital-based study. Epilepsy Res, 174, 106650. https://doi.org/10.1016/j.eplepsyres.2021.106650
  1. Nikbakht, F., Mohammadkhanizadeh, A., & Mohammadi, E. (2020). How does the COVID-19 cause seizure and epilepsy in patients? The potential mechanisms. Multiple sclerosis and related disorders, 46, 102535. https://doi.org/10.1016/j.msard.2020.102535
  2. Lai, S. L., Hsu, M. T., & Chen, S. S. (2005). The impact of SARS on epilepsy: the experience of drug withdrawal in epileptic patients. Seizure, 14(8), 557–561. https://doi.org/10.1016/j.seizure.2005.08.010
  3.  Abu-Rumeileh, S., Abdelhak, A., Foschi, M., Tumani, H., & Otto, M. (2021). Guillain-Barré syndrome spectrum associated with COVID-19: an up-to-date systematic review of 73 cases. Journal of neurology, 268(4), 1133–1170. https://doi.org/10.1007/s00415-020-10124-x   

Disclosures: The listed questions and answers are solely the responsibility of the author and do not necessarily represent the official views of Mercy Hospital-St. Louis or its affiliate healthcare centers, Mass General Hospital, Harvard Medical School or its affiliated institutions, or St. Louis University Medical School. Although every effort has been made to provide accurate information, the author is far from being perfect. The reader is urged to verify the content of the material with other sources as deemed appropriate and exercise clinical judgment in the interpretation and application of the information provided herein. No responsibility for an adverse outcome or guarantees for a favorable clinical result is assumed by the author. Thank you!

Can Covid-19 exacerbate seizures in patients with epilepsy?

What’s the connection between Covid-19 and hypokalemia?

FA Manian MD, MPH, , , , , , , , Leave a comment

The association of hypokalemia with hospitalized Covid-19 patients has been recognized since the early days of the pandemic, with more severe cases associated with lower concentration of serum potassium.1-4

A study involving 175 hospitalized patients with Covid-19 found low serum potassium in 54% of patients with 18% having severe hypokalemia (<3.0 mmol/L) and 37% having serum potassium 3.-3.5 mmol/L.  Compared to patients with mild to moderate Covid-19, those with severe or critical disease were more likely to have low serum potassium (3.5 mmol/L or less) (85% vs 45%).1

Another study involving 306 hospitalized patients with Covid-19, nearly a third (31%) had hypokalemia (3.5 mmol/L or less). Hypokalemia was associated with invasive mechanical ventilation, longer hospital and ICU stays.2 In contrast, a non-peer-reviewed MedRxive study found no association between hypokalemia and ICU admission or in-hospital mortality, possibly related to milder hypokalemia in the patients studied.3

Although various mechanisms may be invoked to explain hypokalemia in hospitalized Covid-19 patients (eg, poor intake, diuretics, corticosteroids, diarrhea, etc…), the most fascinating explanation may revolve around the direct impact of SARS-CoV-2 on the renin-angiotensin system.5  Because this virus uses the enzymatic receptor of ACE2 to penetrate the host cell, it can lead to downregulation of ACE2. Since ACE2 serves as a counterbalance to ACE by transforming a part of angiotensin I and II before they attach to angiotensin II type 1 receptor (AT1R), aldosterone effect is enhanced with resultant hypokalemia. High urinary excretion of potassium in many patients with Covid-19 seem to support the latter hypothesis.1,3  

Who would have predicted the versatility of this virus in causing hypokalemia in addition to all the other physiologic derangements it causes?  

Bonus Pearl: Did you know that there may be an association between lower prevalence of dry cough in patients with Covid-19 and hypokalemia, possibly related to low ACE2—therefore bradykinin— activity mediated by SARS-CoV-2? 2

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References

  1. Chen D, Li X, Song Q, et al. Assessment of hypokalemia and clinical characteristics in patients with coronavirus disease 2019 in Wenzhou, China. JAMA Network Open 2020;3(6):e2011122. https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2767008
  2. Moreno-Perez O, Leon-Ramirez JM, Fuertes-Kenneally L, et al. Hypokalemia as a sensitive biomarker of disease severity and the requirement for invasive mechanical ventilation requirement in COVID-19 pneumonia: A case series of 306 Mediterranean patients. International J Infect Dis 2020;100:449-54. https://www.ijidonline.com/article/S1201-9712(20)30749-9/pdf
  3. Gaetano A, Annachiara F, Francesco F, et al. Hypokalemia in patients with COVID-19. MedRxive preprint. Doi:https://doi.org/10.1101/2020.0614.20131169. https://www.medrxiv.org/content/10.1101/2020.06.14.20131169v2.full.pdf
  4. Lippi G, South Am, Henry BM. Electrolyte imbalances in patients with severe coronavirus disease 2019 (COVID-19). Ann Clin Biochem 2020;57:262-65. https://pubmed.ncbi.nlm.nih.gov/32266828/
  5. Silhol F, Sarlon G, Deharo JC, et al. Downregulation of ACE2 induces overstimulation of renin-angiotensin system in COVID-19: Should we block the renin-angiotensin system? Hypertension Research 2020;43:854-856. https://www.nature.com/articles/s41440-020-0476-3

Disclosures: The listed questions and answers are solely the responsibility of the author and do not necessarily represent the official views of Mercy Hospital-St. Louis or its affiliate healthcare centers. Although every effort has been made to provide accurate information, the author is far from being perfect. The reader is urged to verify the content of the material with other sources as deemed appropriate and exercise clinical judgment in the interpretation and application of the information provided herein. No responsibility for an adverse outcome or guarantees for a favorable clinical result is assumed by the author. Thank you!

What’s the connection between Covid-19 and hypokalemia?

Can my patient with Covid-19 get reinfected?

FA Manian MD, MPH, , , , , , , , Leave a comment

Patients with prior history of Covid-19 have been shown to get reinfected, sometimes less severe and sometimes more severe than the first bout.1-3 What we don’t really know is how often reinfection actually occurs, either with or without symptoms.

Symptomatic reinfection with genetically distinct SARS-CoV-2 following Covid-19 has been reported from several countries, including the USA. 1  A case series of 4 patients (age range of 33-51 y) found the severity of second infection ranging from asymptomatic to more severe disease requiring hospitalization.  First infection was mild in these cases with an intervening period of 48-142 days.1  BNO News, a Dutch website, lists many more “officially confirmed cases” as well as over a thousand “suspected reinfection cases”.4

Reinfection with Covid-19 in at least some people should not be too surprising. Some may have a suboptimal immune response to the first infection (eg with mild infection) that may be short-lasting, while others may have a better response.  Even in those with adequate response, SARS-CoV-2 antibodies may drop rapidly (half-life 36 days according to one study).3 Immunity to several other seasonal respiratory coronaviruses (cousins of SARS-CoV-2) also seems short lived (as short as 6 months).5 How much other arms of the immune system besides antibodies (eg, T cell immunity) play a role in conferring longer lasting immunity remains unclear.

These findings suggest that we cannot rely on natural infection to provide us individual or herd immunity.  Immunization is likely a better answer!

Bonus Pearl: Did you know that preliminary reports suggest that antibody loss with Covid-19 is more rapid than that found for SARS-CoV-1, the agent of SARS pandemic of 2003?3

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References

  1. Iwasaki A. What reinfections mean for COVID-19. Lancet Infect Dis 2020. Published online October 12, 2020. https://www.thelancet.com/journals/laninf/article/PIIS1473-3099(20)30783-0/fulltext
  2. Tillett RL, Sevinsky JR, Hartley PD, et al. Genomic evidence for reinfection with SARS-CoV-2: a case study. Lancet Infect Dis 2020. Published online October 12, 2020. https://www.thelancet.com/pdfs/journals/laninf/PIIS1473-3099(20)30764-7.pdf
  3. Ibarrondo J, Fulcher JA, Goodman-Meza D, et al. Rapid decay of anti-SARS-CoV-2 antibodies in persons with mild Covid-19. N Engl J Med 2020; September 10. https://www.nejm.org/doi/full/10.1056/nejmc2025179
  4. Kunzman K. Contagion Live. October 12, 2020. https://www.contagionlive.com/view/us-reports-first-confirmed-covid-19-reinfection-patient. Accessed Dec 23, 2020.
  5. Edridge AWD, Kaczorowska J, Hoste ACR, et al. Seasonal coronavirus protective immunity is short-lasting. Nature Medicine 2020;26:1691-93. https://pubmed.ncbi.nlm.nih.gov/32929268/

Disclosures: The listed questions and answers are solely the responsibility of the author and do not necessarily represent the official views of Mercy Hospital-St. Louis or its affiliate healthcare centers. Although every effort has been made to provide accurate information, the author is far from being perfect. The reader is urged to verify the content of the material with other sources as deemed appropriate and exercise clinical judgment in the interpretation and application of the information provided herein. No responsibility for an adverse outcome or guarantees for a favorable clinical result is assumed by the author. Thank you!

 

 

Can my patient with Covid-19 get reinfected?

How effective are face masks in reducing transmission of Covid-19?

FA Manian MD, MPH, , , , , , , , , , , Leave a comment

Overall, review of data to date suggests that face masks are quite effective in reducing the transmission of coronaviruses, including SARS-CoV-2, the cause of Covid-19. A Lancet 2020 meta-analysis involving over 12,000 subjects, found that transmission of coronaviruses (SARS-CoV-2, SARS and MERS) was reduced with face masks by 85% (adjusted O.R. 0.15, 95%CI 0.07-0.34).1

More specific to Covid-19, a study from Mass General Brigham hospitals found a significant drop in healthcare worker (HCW) SARS-CoV-2 PCR positivity rate from 21.3% to 11.5% following adoption of universal masking of HCWs and patients.2

An U.S. epidemiologic survey of 2,930 unique counties plus New York City found mandating face mask use in public was associated with a significant decline in the daily Covid-19 growth rate. 3 It was estimated that more than 200,000 Covid-19 cases were averted by May 22, 2020 as a result of the implementation of these mandates.

Another 2020 meta-analysis involving 21 studies reported an overall efficacy of masks (including surgical and N-95 masks) of 80% in healthcare workers and 47% in non-healthcare workers for respiratory virus transmission (including SARS, SARS-CoV-2 and influenza).4

A criticism of above reports has been their primarily retrospective nature. A randomized-controlled Danish study found a statistically insignificant 20% reduction in incident SARS-CoV-2 infection among mask wearers (5,6).    Despite its randomized-controlled design, this study had several limitations, including relatively low transmission rate in the community and lack of universal mask wearing in public during the study period. In addition, less than one-half of participants in the mask group reported adherence to wearing masks, and there was no assurance that masks were worn correctly when they did wear them. 

At most, this study suggests that it’s not enough for the uninfected to wear masks; the infected—often with little or no symptoms— should also wear them to help curb the pandemic.

So please do your part and tell your friends and family members to do the same by masking up while we are at war with Covid-19!

Bonus Pearl: Did you know that universal wearing of masks in the public in response to a respiratory virus pandemic is nothing new?  It was adopted as far back as 100 years ago during the 1918 Spanish influenza pandemic!

References

  1. Chu DK, Akl EA, Duda S, et al. Physical distancing, face masks, and eye protection to prevent person-to-person transmission of SARS-CoV-2 and COVID-19: a systematic review and meta-analysis. Lancet 2020;395: 1973-87. https://www.thelancet.com/pdfs/journals/lancet/PIIS0140-6736(20)31142-9.pdf
  2. Wang X, Ferro EG, Zhou G, et al. Association between universal masking in a health care system and SARS-CoV-2 positivity among health care workers. JAMA 2020;324:703-4. https://jamanetwork.com/journals/jama/fullarticle/2768533
  3. Lyu W, Wehby GL. Community use of face masks and COVID-19: evidence from a natural experiment of state mandates in the US. Health Affairs 2020;39: July 16. https://www.healthaffairs.org/doi/full/10.1377/hlthaff.2020.00818
  4. Liang M, Gao L, Cheng Ce, et al. Efficacy of face mask in preventing respiratory virus transmission: A systematic review and meta-analysis. Travel Med Infect Dis 2020;36:1-8. https://pubmed.ncbi.nlm.nih.gov/32473312/ 
  5. Bundgaard H, Bundgaard JS, Tadeusz DE, et al. Effectiveness of adding a mask recommendation to other public health measures to prevent SARS-CoV-2 infection in Danish mask wearers. Ann Intern Med 2020; November 18. https://pubmed.ncbi.nlm.nih.gov/33205991/
  6. Frieden TR Cash-Goldwasser S. Of masks and methods. Ann Intern Med 2020; November 18. https://www.acpjournals.org/doi/10.7326/m20-7499

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Disclosures: The listed questions and answers are solely the responsibility of the author and do not necessarily represent the official views of Mercy Hospital-St. Louis or its affiliate healthcare centers. Although every effort has been made to provide accurate information, the author is far from being perfect. The reader is urged to verify the content of the material with other sources as deemed appropriate and exercise clinical judgment in the interpretation and application of the information provided herein. No responsibility for an adverse outcome or guarantees for a favorable clinical result is assumed by the author. Thank you!

How effective are face masks in reducing transmission of Covid-19?

What’s the connection between break rooms and transmission of Covid-19 in health care settings?

FA Manian MD, MPH, , , , , , , , , , Leave a comment

Emerging data suggest that healthcare workers (HCWs) may be at increased risk of Covid-19 in break rooms when consuming food or when in the presence of others without a mask.1-4

In a study of over 700 HCWs screened for SARS-CoV-2 by PCR at a university hospital, staying in the same personnel break room as an HCW without a medical mask for more than 15 min and consuming food within 1 meter of an HCW were significantly associated with SARS-CoV-2 infection.1 Consumption of food in break rooms by personnel was thereafter “forbidden” in this facility. Interestingly, 28% of infected personnel in this study lacked symptoms at the time of testing.

A recent outbreak at a Boston hospital involving both patients and HCWs months after institution of strict infection control measures (including universal masking of visitors and HCWs and PCR testing of all patients on admission) traced the outbreak to a variety of factors, including HCWs eating in crowded work rooms.2,3

A CDC study of risk factors among adults 18 years or older with Covid-19 in the community identified dining at a restaurant as significant risk factors for Covid-19.4

Transmission of SARS-CoV-2 during eating or drinking is not surprising because masks cannot be effectively worn during food consumption. Combine eating or drinking with talking, laughing and suboptimal ventilation system and we have all the elements of perfect storm for transmission of Covid-19 during food breaks.

Bonus Pearl: Did you know that, in addition to dining at a restaurant, patients with Covid-19 without known close contact with infected persons have reported higher likelihood of going to bar/coffee shop? 4

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References

 

  1. Celebi G, Piskin N, Beklevic AC, et al. Specific risk factors for SARS-CoV-2 transmission among health care workers in a university hospital. Am J Infect Control 2020;48:1225-30. https://pubmed.ncbi.nlm.nih.gov/32771498/
  2. Freyer FJ. Brigham and Women’s hospital completes investigation of coronavirus outbreak. Boston Globe, October 19, 2020. https://www.bostonglobe.com/2020/10/19/metro/brigham-womens-hospital-completes-investigation-coronavirus-outbreak/
  3. Freyer FJ. At the Brigham, “battle-weary” staff may have allowed virus to slip in. Boston Globe, September 24, 2020. https://www.bostonglobe.com/2020/09/24/metro/brigham-womens-hospital-reports-cluster-10-covid-19-cases/
  4. Fisher KA, Tenforde MW, Felstein LR, et al. Community and close contact exposures associated with COVID-19 among symptomatic adults ≥18 years in 11 outpatient health care facilities—United States, July 2020. MMWR 2020;69:1258-64. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7499837/

Disclosures: The listed questions and answers are solely the responsibility of the author and do not necessarily represent the official views of Mercy Hospital-St. Louis or its affiliates. Although every effort has been made to provide accurate information, the author is far from being perfect. The reader is urged to verify the content of the material with other sources as deemed appropriate and exercise clinical judgment in the interpretation and application of the information provided herein. No responsibility for an adverse outcome or guarantees for a favorable clinical result is assumed by the author. Thank you!

 

 

What’s the connection between break rooms and transmission of Covid-19 in health care settings?

How might measuring viral load in respiratory specimens be helpful clinically in patients with Covid-19?

FA Manian MD, MPH, , , , , , Leave a comment

Although far from being perfect, there are emerging scientific data that suggest measuring viral load in respiratory specimens of patients with Covid-19 could be helpful in at least 2 ways: 1. Help determine who may be infectious (therefore isolated or undergo contact tracing); and 2. Identify patients at high risk for severe disease and death (1-4).

In a study involving 3,790 nasopharyngeal samples testing positive for SARS-CoV-2 by PCR, a significant correlation was found between isolation of the virus by culture—therefore potential contagiousness—and viral load determined by cycle threshold (CT) (ie, the number of cycles needed to detect the virus with higher numbers thought to be associated with lower risk of contagion) (2). Some have suggested that patients with CT above 33-34 are no longer contagious (3).

In another study involving 978 patients with Covid-19, high viral load in nasopharyngeal specimens was associated with higher risk of intubation (O.R. 2.7, 1.7-4.4), and mortality (6.1, 2.9-12.5) (4).

In addition, simultaneous presence of high viral loads in the respiratory specimens in the population suggests an expanding outbreak, while low viral loads may imply that the outbreak is waning (1).

Some have cautioned against over-reliance on viral loads in Covid-19 due to factors such as variation in the technique of obtaining specimens and testing instruments (5).

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References
1. Service RF. Covid-19. A call for diagnostic tests to report viral load. Science 2020, October 2;370:22. https://www.sciencemag.org/news/2020/09/one-number-could-help-reveal-how-infectious-covid-19-patient-should-test-results
2. Jaafar R, Aherfi S, Wurtz N, et al. Correlation between 3790 qPCR positives samples and positive cell cultures including 1941 SARS-CoV-2 isolates. Clin Infect Dis 2020, September. https://pubmed.ncbi.nlm.nih.gov/32986798/
3. La Scola B, Le Bideau M, Andreani J, et al. Viral RNA as determined by cell culture as a management tool for discharge of SARS-CoV-2 patients from infectious disease wards. Eur J Clin Microbiol Infect Dis 2020;39:1059-1061. https://pubmed.ncbi.nlm.nih.gov/32342252/
4. Magleby R, Westblade LF, Trzebucki A, et al. Impact of severe acute respiratory syndrome coronavirus 2 viral load on risk of intubation and mortality among hospitalized patients with coronavirus disease 2019. Clin Infect Dis 2020. https://academic.oup.com/cid/advance-article/doi/10.1093/cid/ciaa851/5865363
5. Rhoads D, Peaper DR, She RC, et al. College of American Pathologists (CAP) Microbiology Committee perspective: caution must be used in interpreting the cycle threshold (Ct) value. Clin Infect Dis 12 August, 2020. https://academic.oup.com/cid/advance-article/doi/10.1093/cid/ciaa1199/5891762

 

Disclosures: The listed questions and answers are solely the responsibility of the author and do not necessarily represent the official views of Massachusetts General Hospital, Harvard Catalyst, Harvard University, its affiliate academic healthcare centers, or its contributors. Although every effort has been made to provide accurate information, the author is far from being perfect. The reader is urged to verify the content of the material with other sources as deemed appropriate and exercise clinical judgment in the interpretation and application of the information provided herein. No responsibility for an adverse outcome or guarantees for a favorable clinical result is assumed by the author. Thank you!

How might measuring viral load in respiratory specimens be helpful clinically in patients with Covid-19?

Why would my patient with Covid-19 infection test negative by PCR?

FA Manian MD, MPH, , , , , , , , , , Leave a comment

There are several potential reasons why someone who is infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the agent of Covid-19, may test negative by PCR. These including the threshold for detection of virus (which can vary among different manufacturers from as low as 100 viral copies/ml to >6,000 copies/ml),1 timing of the sample collection with respect to infection stage (lowest false-negative rate [~20%] on day 3 of symptoms or 8 days post-infection),2  specimen storage and transport and, particularly in the case of nasopharyngeal specimens, the adequacy of the sample obtained. 3

Suboptimal specimen collection from nasopharynx has long been suspected as an explanation for false-negative PCR tests in patients who subsequently have a positive test or are highly suspected of having Covid-19, but without any good support data. Until now…

A clever study looked at the presence of human DNA recovered from nasopharyngeal swabs as a marker for adequate specimen collection quality and found that human DNA levels were significantly lower in samples from patients with confirmed or suspected Covid-19 that yielded negative results compared to those of representative pool of samples submitted for Covid-19 testing.3

Interestingly, major commercial assays do not include any internal controls that ensure adequate sampling before testing for SARS-CoV2.

A typical microbiology lab can reject a sputum culture if gram-stain suggests poor quality specimen (eg, saliva only) but it looks like no similar rule exists for nasopharyngeal PCR tests for SARS-CoV-2 through commercial labs. Apparently, the US-CDC diagnostic panel does include a human RNAseP RNA-specific primer/probe set but the interpretation criteria for this control may also be too liberal.3

For these reasons, in patients highly suspected of having Covid-19 but with a negative initial PCR test, a repeat test on the same day or next 2 days is recommended.4

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References

  1. Prinzi A. False negatives and refinfections: the challenges of SARS-CoV-2 RT-PCR testing. Available at https://asm.org/Articles/2020/April/False-Negatives-and-Reinfections-the-Challenges-of     Accessed October 5, 2020.
  2. Kucirka LM, Lauer SA, Laeyendecker O, et al. Variation in false-negative rate of reverse transcriptase polymerase chain reaction-based SARS-CoV-2 tests by time since exposure. Ann Intern Med 2020 May 13:M20-1495. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7240870/
  3. Kinloch NN, Ritchie G, Brumme CJ, et al. Suboptimal biological sampling as a probable cause of false-negative COVID-19 diagnostic test results. J Infect Dis 2020;222:899-902. https://academic.oup.com/jid/article/222/6/899/5864227
  4. Green DA, Zucker J, Westbade LF, et al. Clinical performance of SARS-CoV-2 molecular testing. J Clin Microbiol 2020. DOI:10.1128/JCM.00995-20. https://jcm.asm.org/content/58/8/e00995-20

 

Disclosures: The listed questions and answers are solely the responsibility of the author and do not necessarily represent the official views of Massachusetts General Hospital, Harvard Catalyst, Harvard University, its affiliate academic healthcare centers, or its contributors. Although every effort has been made to provide accurate information, the author is far from being perfect. The reader is urged to verify the content of the material with other sources as deemed appropriate and exercise clinical judgment in the interpretation and application of the information provided herein. No responsibility for an adverse outcome or guarantees for a favorable clinical result is assumed by the author. Thank you!

Why would my patient with Covid-19 infection test negative by PCR?

How often is Covid-19 in hospitalized patients complicated by bacterial infection?

FA Manian MD, MPH, , , , , , , , , , Leave a comment

Despite frequent use of empiric antibiotics in hospitalized patients with Covid-19,1  current data suggests a low rate of documented bacterial co-infection (BCI) in such patients. In fact, the overall reported rate of BCI in hospitalized patients with Covid-19 is generally no greater than 10%.1-3   It’s quite likely that most patients with Covid-19 and chest radiograph changes solely have a coronavirus (SARS-CoV-2) lung infection,4 particularly early in the course of the disease.  

A meta-analysis involving 30 studies (primarily retrospective) found that overall 7% of hospitalized Covid-19 patients had a laboratory-confirmed BCI with higher proportion among ICU patients (14%). 2 Mycoplasma pneumoniae was the most common (42% of BCIs), followed by Pseudomonas aeruginosa and H. influenzae.  Notably, diagnosis of M. pneumoniae infection was based on antibody testing for IgM, which has been associated with false-positive results. Other caveats include lack of a uniform definition of respiratory tract infection among studies and potential impact of concurrent or prior antibiotic therapy on the yield of bacteriologic cultures. 5,6

A low prevalence of BCI was also found in a UK study involving 836 hospitalized Covid-19 patients: 3.2% for early BCI (0-5 days after admission) and 6.1% throughout hospitalization, including hospital-acquired infections.7  Staphylococcus aureus was the most common respiratory isolate among community-acquired cases, while Pseudomonas spp. was the predominant healthcare associated respiratory isolate.  Similarly, S. aureus. and Streptococcus pneumoniae were the most commonly isolated organisms from blind bronchoalveolar lavage of critically ill patients with Covid-19 during their first 5 days of admission, while gram-negative bacilli became dominant later during the hospitalization.8

The discordance between high rates of antibiotic treatment and confirmed bacterial co-infection in Covid-19 patients is likely a reflection of the difficulty in distinguishing Covid-19 pneumonia from bacterial pneumonia based on clinical or radiographic findings alone.

We need better tests to help distinguish bacterial vs Covid-19 pneumonia. Some have suggested using a low serum procalcitonin to help guide the withholding of or early discontinuation of antibiotics, especially in less severe Covid-19 cases. 1  Formal studies of the accuracy of procalcitonin in Covid-19 are needed to test this hypothesis, given its suboptimal sensitivity in bacterial community-acquired pneumonia. 

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Reference

  1. Stevens RW, Jensen K, O’Horo JC, et al. Antimicrobial prescribing practices at a tertiary-care center in patients diagnosed with COVID-19 across the continuum of care. Infect Control Hosp Epidemiology 2020. https://reference.medscape.com/medline/abstract/32703323
  2. Lansbury L, Lim B, Baskaran V, et al. Co-infections in people with COVID-19: a systematic review and meta-analysis. J Infect 2020;81:266-75. https://pubmed.ncbi.nlm.nih.gov/32473235/
  3. Rawson TM, Moore LSP, Zhu N. Bacterial and fungal co-infection in individuals with coronavirus: A rapid review to support COVID-19 antimicrobial prescribing. Clin Infect Dis 2020 (Manuscrpit published online ahead of print 2 June ). Doi:10.1093/cid/ciaa530.https://pubmed.ncbi.nlm.nih.gov/32358954/
  4. Metlay JP, Waterer GW. Treatment of community-acquired pneumonia during the coronavirus 2019 (COVID-19) pandemic. Ann Intern Med 2020; 173:304-305. https://pubmed.ncbi.nlm.nih.gov/32379883/
  5. Chang CY, Chan KG. Underestimation of co-infections in COVID-19 due to non-discriminatory use of antibiotics. J Infect 2020;81:e29-30. https://pubmed.ncbi.nlm.nih.gov/32628960/
  6. Rawson TM, Moore LSP, Zhu N, et al. Bacterial pneumonia in COVID-19 critically ill patients: A case series. Reply letter. Clin Infect Dis 2020. https://academic.oup.com/cid/advance-
  7. Hughes S, Troise O, Donaldson H, et al. Bacterial and fungal coinfection among hospitalized patients with COVID-19: a retrospective cohort study in a UK secondary-care setting. Clin Microbiol Infect 2020. https://www.clinicalmicrobiologyandinfection.com/article/S1198-743X(20)30369-4/fulltext
  8. Dudoignon E, Camelena F, Deniau B, et al. Bacterial pneumonia in COVID-19 critically ill patients: A case series. Clin Infect Dis 2020. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7337703/

Disclosures: The listed questions and answers are solely the responsibility of the author and do not necessarily represent the official views of Massachusetts General Hospital, Harvard Catalyst, Harvard University, its affiliate academic healthcare centers, or its contributors. Although every effort has been made to provide accurate information, the author is far from being perfect. The reader is urged to verify the content of the material with other sources as deemed appropriate and exercise clinical judgment in the interpretation and application of the information provided herein. No responsibility for an adverse outcome or guarantees for a favorable clinical result is assumed by the author. Thank you!

How often is Covid-19 in hospitalized patients complicated by bacterial infection?