What’s so “special” about SARS-CoV-2 Omicron subvariants BA.4 and BA.5?

BA.4 and BA.5 now account for the majority of Covid cases in the U.S.1  Several concerning features of BA.4 and BA.5 when compared to earlier strains of SARS-CoV-2 include:2-6

  1. High reproductive rate or R0 ie, the average number of new infections generated by an infectious person in a totally naïve population. BA.4/5 has an estimated R0 of 18.6, according to a one report.  For comparison, the R0 for the original Wuhan variant was estimated at 3.3, for Delta  5.1, early Omicron  9.5, BA.1 13.3, mumps 12, and measles 18.  So, it’s not surprising that we are currently experiencing higher rates of SARS-CoV-2 transmission in the population than just a few weeks ago.3
  2. Suboptimal existing immunity following prior infections due to Omicron variants BA.1 and BA.2, or prior vaccinations (including 3 doses of Pfizer vaccine).2,4
  3. More efficient spread than BA.2 when studied in human lung cells invitro. 2
  4. More pathogenic than BA.2 in hamsters. 2
  5. Reduced activity of SARS-CoV-2 therapeutic monoclonal antibodies.4
  6. Antigenically distant from other SARS-CoV-2 variants, with 50 mutations, including more than 30 on the spike protein, the viral protein targeted by Covid vaccines to induce immunity.5,6

Despite these potentially ominous traits, currently there is no evidence that  BA.4 or BA.5 is inherently more likely to cause severe disease than that caused by other Omicron subvariants.   The sheer number of infected persons in the population due to high transmission rates, however, will likely translate into higher hospitalization and deaths which has already happened in many areas.

High transmission rates also mean that we should not abandon the usual public health measures (eg, social distancing, masking indoors in public spaces) and vaccination with boosters for eligible persons with the aim of reducing hospitalization and death, if not infections.  

Bonus Pearl: Did you know that BA.4 and BA.5 became dominant in South Africa in April, 2022, despite 98% of the population reportedly having some antibodies from vaccination or previous infection or both?  

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References

  1. Leatherby L. What the BA.5 subvariant could mean for the United States. NY Times, July 7, 2022. https://theconversation.com/australia-is-heading-for-its-third-omicron-wave-heres-what-to-expect-from-ba-4-and-ba-5-185598
  2. Kimura I, Ymasoba D, Tamura T, et al. Virological characteristics of the novel SARS-CoV-2 Omicron variants including BA.2.12.1, BA.4 and BA.5. bioRxiv, preprint doi: https://doi.org/10.1101/2022.05.26.493539 , posted May 26, 2022. Accessed July, 13, 2022.
  3. Esterman D. The Conversation. Australia is heading for its third Omicron wave. Here’s what to expect from BA.4 and BA.5. July 4, 2022. https://theconversation.com/australia-is-heading-for-its-third-omicron-wave-heres-what-to-expect-from-ba-4-and-ba-5-185598
  4. Tuekprakhon A, Nutalai R, Dijokaite-Guraliuc A, et al. Antibody escape of SARS-COV-2 Omicron BA.4 and BA.5 from vaccine and BA.1 serum.
  5. Katella K. Omicron and BA.5: A guide to what we know. YaleMedicine, July 6, 2022. https://www.yalemedicine.org/news/5-things-to-know-omicron
  6. Topol E. The BA.5 story. The takeover by this Omicron sub-variant is not pretty. Ground Truths. June 27, 2022. https://erictopol.substack.com/p/the-ba5-story

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!

What’s so “special” about SARS-CoV-2 Omicron subvariants BA.4 and BA.5?

Why might convalescent sera or plasma transfusion therapy be effective in the treatment of patients with Covid-19?

Of the myriad therapeutic approaches currently under consideration in our fight against Covid-19, convalescent sera/plasma therapy (CSPT) is particularly promising. The principle behind CSPT is to provide immediate immunity to susceptible people by administering the serum or plasma—therefore antibodies—of individuals who have successfully recovered from Covid-19.1

The theory behind using antibody-containing blood products to treat infections is by no means new and goes back to the 1890s when serum from exposed animals who recovered from disease was used to protect healthy animals against tetanus and diphtheria.2

Historically, CSPT has been used against poliomyelitis, measles, mumps, and influenza, and more recently in a smaller number of patients with SARS, H5N1 and H7N9 avian influenza and Ebola.1,3-8 A 2015 systematic review and exploratory meta-analysis of 32 studies involving severe acute respiratory infections of viral etiology (including influenza and SARS) found a reduction in mortality (odds ratio, 0.25, 95% C.I. 0.14-0.45), particularly when CSPT was administered early into the illness.3

Experience with 1918 Spanish influenza pandemic: A meta-analysis of 1703 hospitalized patients (Yes, scientists performed wonderful studies back then too despite a pandemic!) during the 1918 Spanish influenza pandemic demonstrated decreased mortality with administration of convalescent blood products with crude case-fatality rates dropping by one-half (16% vs 37% in controls)! Notably, patients who were treated within 4 days of pneumonia had one-third the case-fatality rate compared to those treated later.3

Experience with 2002-2004 SARS epidemic: A retrospective study from Hong Kong involving 80 patients with SARS (caused by another coronavirus, SARS-CoV-1) not responding to antibiotics/steroids/interferon but receiving CSPT reported a lower mortality rate with near significant (P=0.08) improvement in outcome and reduced mortality in the group that received CSPT before day 14 of the illness (6.3% vs 21.9%).4

What about Covid-19? A very preliminary report out of China involving 5 mechanically-ventilated patients with ARDS and rapid progression despite corticosteroids and antivirals found clinical improvement in all 5 patients. More specifically, body temperature normalized within 3 days in 4 of 5 patients and ARDS resolved in 4 patients at 12 days following transfusion, 2 patients were in stable condition and 3 patients were eventually discharged from the hospital.9

Of course, we should be mindful of potential adverse reactions due to CSP as well, such as allergic reactions, infections, transfusion-related acute lung injury (TRALI), and theoretical risk of antibody-dependent enhancement of infection (ADE).1 Only properly designed clinical studies can shed light on the safety and efficacy of CSPT in Covid-19.

Nevertheless, the historical data on the use of CSPT in serious viral infections is encouraging. In fact, the first US studies of CSPT in Covid-19 have already been approved by the FDA!10 Stay tuned!

Bonus pearl: Did you know that serum and plasma both refer to the noncellular fluid part of blood, but serum is collected after coagulation factors (fibrinogen) have been removed. Fortunately, both contain antibodies!

 

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Contributed by Bruce Tiu, Harvard Medical Student, Boston, MA.

References:

  1. Casadevall A, Pirofski L. The convalescent sera for containing COVID-19. J Clin Invest. 2020;130(4):1545-1548. doi: 10.1172/JCI138003 https://www.jci.org/articles/view/138003
  2. Eibl MM. History of immunoglobulin replacement. Immunol Allergy Clin North Am. 2008;28(4):737–viii. doi:10.1016/j.iac.2008.06.004 https://www.sciencedirect.com/science/article/abs/pii/S0889856108000702
  3. Mair-Jenkins J, Saavedra-Campos M, Baillie K, et al. The effectiveness of convalescent plasma and hyperimmune immunoglobulin for the treatment of severe acute respiratory infections of viral etiology: A systematic review and exploratory meta-analysis. J Infect Dis 2015; 211: 80-90. https://academic.oup.com/jid/article/211/1/80/799341
  4. Luke TC, Kilbane EM, Jackson JL, et al. Meta-Analysis: Convalescent Blood Products for Spanish Influenza Pneumonia: A Future H5N1 Treatment?. Ann Intern Med. 2006;145:599–609. doi: 10.7326/0003-4819-145-8-200610170-00139 https://annals.org/aim/article-abstract/729754/meta-analysis-convalescent-blood-products-spanish-influenza-pneumonia-future-h5n1
  5. Cheng Y, Wong R, Soo YO, et al. Use of convalescent plasma therapy in SARS patients in Hong Kong. Eur J Clin Microbiol Infect Dis. 2005;24(1):44–46. doi:10.1007/s10096-004-1271-9 https://link.springer.com/article/10.1007/s10096-004-1271-9
  6. Zhou B, Zhong N, Guan Y. Treatment with convalescent plasma for influenza A (H5N1) infection. N Engl J Med. 2007;357:1450–1. doi: 10.1056/NEJMc070359 https://www.nejm.org/doi/full/10.1056/NEJMc070359
  7. Chen L, Xiong J, Bao L, et al. Convalescent plasma as a potential therapy for COVID-19. Lancet Infect Dis 2020;20: 398-400. https://www.thelancet.com/journals/laninf/article/PIIS1473-3099(20)30141-9/fulltext
  8. Wu XX, Gao HN, Wu HB, Peng XM, Ou HL, Li LJ. Successful treatment of avian-origin influenza A (H7N9) infection using convalescent plasma. Int J Infect Dis. 2015;41:3–5. doi: 10.1016/j.ijid.2015.10.009 https://www.ncbi.nlm.nih.gov/pubmed/26482389
  9. Shen C, Wang Z, Zhao F, et al. Treatment of 5 Critically Ill Patients With COVID-19 With Convalescent Plasma. JAMA. Published online March 27, 2020. doi:10.1001/jama.2020.4783 https://jamanetwork.com/journals/jama/fullarticle/2763983
  10. https://thehill.com/regulation/healthcare/490768-first-us-coronavirus-patients-being-treated-with-plasma-therapy.

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 might convalescent sera or plasma transfusion therapy be effective in the treatment of patients with Covid-19?

5 Covid-19 facts worth keeping in mind as we deal with our pandemic anxiety

As an infectious disease physician who had the privilege of caring for many patients during the unsettling times of the early HIV epidemic and the more recent H1N1 pandemic influenza, I fully understand the widespread anxiety the current Covid-19 pandemic has inflicted on our society.

Here are 5 scientific facts that may be worth remembering as we try to deal with our pandemic anxiety.

 
1. On transmission in the community: For sure, Covid-19 is transmitted in the community but I am glad that it behaves more like influenza which is primarily contracted through close personal contact and droplets, and less like measles or chickenpox which are considered airborne with viral particles travelling lingering in the air for long periods of time. On average, a patient with Covid-19 may infect 2-3 susceptible contacts vs as many as 12 or more in the case of patients with measles or chickenpox (1, 2).

 
2. On transmission in healthcare settings: For sure, Covid-19 can be transmitted in the healthcare settings, just like other coronaviruses, such severe acute respiratory syndrome (SARS) or Middle East respiratory syndrome (MERS) coronaviruses. But the good news is that, in the absence of aerosol-producing procedures (eg, intubation, nebulizer therapy) it doesn’t seem to behave like an airborne virus (see above) and adherence to droplet and contact precautions, including donning of masks, gowns, eye protection and hand hygiene has been effective (3, 4).

 
3. On surface viability after cleaning/disinfection: For sure, the novel 2019 coronavirus SARS-CoV-2, the cause of Covid-19, can be found on surfaces outside of the body. But the good news is that, in contrast to hardy viruses such as norovirus, it succumbs to common disinfection and environmental cleaning procedures. That’s because  coronaviruses have a lipid envelope that easily falls apart under usual cleaning and disinfection of surfaces. That means that simple handwashing with soap and water (minimum 20 seconds), alcohol containing hand hygiene products, detergents and diluted bleach should easily inactivate it (5-9) and that’s good!

 
4. On the course of Covid-19: For sure, Covid-19 can make people very sick and, tragically, may be fatal on occasion. But compared to diseases caused by other recent respiratory coronaviruses such as MERS or SARS, the overall mortality associated with Covid-19 is much lower (often ~ 2.0-3.0% or lower vs 36.0% for MERS and ~10.0% for SARS) (1). In fact, the majority of patients (~80%) may have no symptoms or only have mild disease (10). I am thankful that we are not dealing with a transmissible respiratory virus that has mortality rates like that of MERS.

 
5. On the timing of this pandemic: We are fortunate that this is 2020 not 1918-19 when a particularly virulent form of influenza, dubbed as “the mother of all pandemics” infected some 500 million people (a third of the world’s population at the time) and accounted for an estimated 50 million deaths (11). Imagine fighting a pandemic without the technology to identify its cause. Imagine fighting a pandemic without access to the miracles of modern science and medicine, including antibiotics for secondary bacterial pneumonia, artificial ventilation, dialysis, ICU support, and capability to screen for an infectious agent.  Imagine fighting a pandemic without scientific tools to develop effective antimicrobials or vaccines. Imagine fighting a pandemic without the luxury of the internet.

 
As unprepared as we all feel in combatting Covid-19, I take solace in the fact that our armamentarium and collective determination to mount an effective response to this pandemic has never been better. Even during these uncertain times, I reflect on what could have been and remain optimistic. Be safe!

 

 

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References:
1. Fauci AS, Lane HC, Redfield RR. Covid-19—Navigating the uncharted. N Eng J Med 2020. DOI:10.1056/NEJMe2002387. https://www.nejm.org/doi/full/10.1056/NEJMe2002387
2. Delamater PL, Street EJ, Leslie TF, et al. Complexity of the basic reproduction number (R0). Emerg infect Dis 2019;25:1-4. https://wwwnc.cdc.gov/eid/article/25/1/17-1901_article
3. Seto WH, Tsang D, Yung RWH, et al. Effectiveness of precautions against droplets and contact in prevention of nosocomial transmission of severe acute respiratory syndrome (SARS). Lancet 2003;361:1519-20. https://www.sciencedirect.com/science/article/pii/S0140673603131686
4. Ng K, Poon BH, Puar THK, et al. COVID-19 and the risk to health care workers: a case report. Ann Intern Med. 2020, March 16. https://annals.org/aim/fullarticle/2763329/covid-19-risk-health-care-workers-case-report
5. van Doremalen N, Bushmaker, Morris DH, et al. Aerosol and surface stability of HCoV-19 (SARS-CoV-2) compared to SARS-CoV-1. N Engl J Med 2020. https://doi.org/10.1101/2020.03.09.20033217
6. Kampf G. Efficacy of ethanol against viruses in hand disinfection. J Hosp Infect 2018;98:331-38. https://www.sciencedirect.com/science/article/pii/S0195670117304693
7. Grayson ML, Melvani S, Druce J, et al. Efficacy of soap and water and alcohol-based hand-rub preparations against live H1N1 influenza virus on the hands of human volunteers Clin Infect Dis 2009;48:285-91. https://www.ncbi.nlm.nih.gov/pubmed/19115974/
8. Service RF. Does disinfecting surfaces really prevent the spread of coronavirus? Science 2020, March 12. https://www.sciencemag.org/news/2020/03/does-disinfecting-surfaces-really-prevent-spread-coronavirus
9. CDC. Norovirus. https://www.cdc.gov/vitalsigns/norovirus/index.html
10. Guan W, Ni Z, Hu Y, et al. Clinical characteristics of Coronavirus disease 2019 in China. N Engl J Med 2020. First published Feb 28, 220, last updated March 6, 2020. https://www.nejm.org/doi/10.1056/NEJMoa2002032
11. Taubenberger JK, Morens DM. 1918 influenza: the mother of all pandemics. Emerg Infect Dis 2006;12:15-22. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3291398/

 

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!

 

 

5 Covid-19 facts worth keeping in mind as we deal with our pandemic anxiety

My patient with erythema multiforme has tested positive for Mycoplasma pneumoniae IgM antibody. Does this mean she has an acute M. pneumonia infection as the cause of her acute illness?

Not necessarily! Although detection of IgM in the serum of patients has proven valuable in diagnosing many infections during their early phase, particularly before IgG is detected, less well known is that false-positive IgM results are not uncommon. 1

More specific to M. pneumoniae IgM, false-positive results have been reported in 10-80% of patients without a clinical diagnosis of acute M. pneumoniae infection 2-4 and 3-15% of blood donors. 4

False-positive IgM results may also occur when testing for other infectious agents, such as the agent of Lyme disease (Borrelia burgdorferi), arboviruses (eg, Zika virus), and herpes simplex, Epstein-Barr, cytomegalovirus, hepatitis A and measles viruses. 1,5  

Reports of false positive IgM results include a patient with congestive heart failure and mildly elevated liver enzymes who had a false-positive hepatitis IgM which led to unnecessary public health investigation and exclusion from an adult day care center. 1 Another patient with sulfa rash had a false-positive measles IgM antibody resulting in callback of >100 patients and healthcare providers for testing!5

There are many potential mechanisms for false-positive IgM results, including polyclonal B cell activation, “vigorous immune response”, cross-reactive antibodies, autoimmune disease, subclinical reactivation of latent viruses, influenza vaccination, overreading weakly reactive results, and persistence of antibodies long after the resolution of the acute disease. 1,2

In our patient, a significant rise in M. pneumoniae IgG between acute and convalescent samples several weeks apart may be more helpful in diagnosing an acute infection accounting for her erythema multiforme.

 

References

  1. Landry ML. Immunoglobulin M for acute infection: true or false? Clin Vac Immunol 2016;23:540-5. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4933779/
  2. Csango PA, Pedersen JE, Hess RD. Comparison of four Mycoplasma pneumoniae IgM-, IgG- and IgA-specific enzyme immunoassays in blood donors and patients. Clin Micro Infect 2004;10:1089-1104. https://www.clinicalmicrobiologyandinfection.com/article/S1198-743X(14)63853-2/pdf
  3. Thacker WL, Talkington DF. Analysis of complement fixation and commercial enzyme immunoassays for detection of antibodies to Mycoplasma pneumoniae in human serum. Clin Diag Lab Immunol 2000;7:778-80. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC95955/
  4. Ryuta U, Juri O, Inoue Y, et al. Rapid detection of Mycoplasma pneumoniae IgM antibodies using immunoCard Mycoplasma kit compared with complement fixation (CF) tests and clinical application. European Respiratory Journal 2012; 40: P 2466 (Abstract). https://erj.ersjournals.com/content/40/Suppl_56/P2466 
  5. Woods CR. False-positive results for immunoglobulin M serologic results: explanations and examples. J Ped Infect Dis Soc 2013;2:87-90. https://www.ncbi.nlm.nih.gov/pubmed/26619450

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My patient with erythema multiforme has tested positive for Mycoplasma pneumoniae IgM antibody. Does this mean she has an acute M. pneumonia infection as the cause of her acute illness?