Beyond masks and hand hygiene, what factors impact transmission of Covid-19 in indoor gatherings?

Aside from factors specific to the source individual (eg, viral load in exhaled air, “superspreader” features, etc…) and host characteristics (eg, older age, obesity, immunocompromised state), transmission of SARS-CoV-2 in indoor settings may be impacted by several factors, including social distancing, ventilation of rooms/ direction of airflow, room occupancy, exposure time and higher risk activities, such as eating, talking loud, heavy breathing during exercise, laughing, coughing and sneezing. 1-4

  1. Physical distance from infected individuals. Although a “safe” distance of 6 feet has often been cited, increasing evidence suggests that SARS-CoV-2 may be spread not only by larger droplets but also by airborne route (ie, beyond 6 feet or shortly after an infected person leaves the area). In fact, 8 of 10 studies on horizontal droplet distance have reported droplets traveling more than 6 feet (2 meters), some cases up to 26 feet (8 meters), and 1 study documented virus at 13 feet (4 meters). Transmission beyond 6 feet is not surprising since even as early as 1948 beta streptococci were found 9.5 feet from 10% of people who were infected!1
  2. Quality of ventilation and direction of airflow in the room. Poorly ventilated rooms would be expected to have more potentially infectious droplets in the air for longer periods of time, even after an infected person leaves the area.
  3. Room occupancy. The higher the occupancy the more likely to have exhaled contaminated air from 1 or more infected persons (symptomatic or asymptomatic) with exposure of susceptible hosts.
  4. Exposure time. Exposure to contaminated air in the room even for a relatively short period of time (ie, >5-15 minutes) is likely to increase the risk of transmission.
  5. Activity of infected individual. Many activities such as singing, speaking loudly, eating, laughing, breathing heavily during exercise, coughing and sneezing may increase risk of Covid-19 transmission in indoor settings.

Recall that over one-half of Covid-19 transmissions are due to asymptomatic individuals.5 In this setting and in the presence of factors discussed above, it’s easy to see how transmission of Covid-19 in indoor settings can occur readily, possibly explaining cases without apparent source.

Bonus Pearl: Did you know that the odds of Covid-19 transmission may be 18.7 times greater indoors compared to open-air environment and the odds of superspreading event in closed environments may be 32.6 times higher?4

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References

  1. Bahl P, Doolan C, de Silva C, et al. Airborne or droplet precautions for health workers treating coronavirus disease 2019? J Infect Dis 2020. Published online April 16, 2020. https://pubmed.ncbi.nlm.nih.gov/32301491/
  2. Jones NR, Quereshi Z, Temple RJ, et al. Two metres or one: what is the evidence for physical distancing in covid-19? BMJ 2020;370:m3223. https://www.bmj.com/content/370/bmj.m3223/rr-18
  3. Johansson MA, Quandelacy TM, Kada S, et al. SARS-CoV-2 transmission from people without COVID-19 symptoms. JAMA Network open. 2021;4():e2035057. https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2774707?utm_source=For_The_Media&utm_medium=referral&utm_campaign=ftm_links&utm_term=010721
  4. Nishiura H, Oshitani H, Kobayashi T, et al. Closed environments facilitate secondary transmission of coronavirus disease 2019 (COVID-19). MedRxiv 2020. https://www.medrxiv.org/content/10.1101/2020.02.28.20029272v2.full.pdf
  5. Leclerc QJ, Fuller NM, Knight LE,e tal. What settings have been linked to SARS-CoV-2 transmission clusters? Wellcome Open Research October, 2020. https://wellcomeopenresearch.org/articles/5-83    

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!

Beyond masks and hand hygiene, what factors impact transmission of Covid-19 in indoor gatherings?

Key clinical pearls on the management of patients suspected of or diagnosed with Covid-19 in the outpatient setting

Here are some key points to remember when managing patients with Covid-19 symptoms in the outpatient setting.  These points are primarily based on the CDC guidelines and the current literature. They may be particularly useful to primary care providers (PCP) who do not have ready access to Covid-19 test kits or radiographic imaging in the diagnosis of patients suspected of or diagnosed with Covid-19.

  • Isolation precautions. 1,6-7 Minimize chances of exposure by placing a facemask on the patient and placing them in an examination room with the door closed. Use standard and transmission-based precautions including contact and airborne protocols when caring for the patient. Put on an isolation gown and N95 filtering facepiece respirator or higher. Use a facemask if a respirator is not available. Put on face shield or goggles if available. Adhere to strict hand hygiene practices with the use of alcohol-based hand rub with greater than 60% ethanol or 70% isopropanol before and after all patient contact. If there is no access to alcohol-based hand sanitizers, the CDC recommends hand washing with soap and water as the next best practice.

 

  • Risk Factors.2-3 Older patients and patients with severe underlying medical conditions seem to be at higher risk for developing more serious complications from Covid-19 illness. Known risk factors for severe Covid-19 include age over 60 years, hypertension, diabetes, cardiovascular disease, chronic respiratory disease, and immunosuppression.

 

  • Symptoms.2,4,8,9 Reported illnesses have ranged from mild symptoms to severe illness and death. These symptoms may appear after a 2- to 14-day incubation period.
    • Fever at any time 88-99%
    • Cough 59-79%
    • Dyspnea 19-55%
    • Fatigue 23-70%
    • Myalgias 15%-44%
    • Sputum production 23-34%
    • Nausea or vomiting 4%-10%
    • Diarrhea 3%-10%
    • Headache 6%-14%
    • Sore throat 14%
    • Rhinorrhea/nasal congestion (4.8%)
    • Anosmia (undocumented percentage)

 

  • Treatment for mild illness.5 Most patients have mild illness and are able to recover at home. Counsel patients suspected to have Covid-19 to begin a home quarantine staying in one room away from other people as much as possible. Patients should drink lots of fluids to stay hydrated and rest. Over the counter medicines may help with symptoms. There is controversy regarding the safety of NSAIDs in Covid-19 (See related P4P pearl). Generally, symptoms last a few days and  patients get better after a week. There is no official guidance from the CDC or other reliable sources on how often a PCP should check in with a patient confirmed with Covid-19 and in quarantine. Please use good judgement and utilize telehealth capabilities via phone call, video call, etc… if possible.

 

  • Treatment for severe illness.3 Patients should be transferred immediately to the nearest hospital. If there is no transfer service available, a family member with appropriate personal protective equipment (PPE) precautions, should drive patient to nearest hospital for critical care services.

 

  • Ending home isolation. 5
    • Without testing: Patients can stop isolation without access to a test result after 3 things have happened. 1) No fever for at least 72 hours. This is 3 full days of no fever and without the use of medication that reduces fever; 2) Respiratory symptoms have improved.; and 3) At least 7 days have passed since symptoms first appeared.
    • With testing. 5 Home isolation may be ended after all of the following 3 criteria have been met: 1) No fever for at least 72 hours. This is 3 full days of no fever and without the use of medication that reduces fever; 2) Respiratory symptoms have improved; and 3) Negative results from at least 2 consecutive nasopharyngeal swab specimens collected more than 24 hours apart.

To all the healthcare providers out there, please be safe and stay healthy!

 

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Contributed by Erica Barnett, Harvard Medical Student, Boston, MA.

 

References:

  1. CDC. Evaluating and Testing Persons for Coronavirus Disease 2019 (COVID-19). https://www.cdc.gov/coronavirus/2019-nCoV/hcp/clinical-criteria.html
  2. CDC. Symptoms and Testing. https://www.cdc.gov/coronavirus/2019-ncov/symptoms-testing/index.html
  3. World Health Organization. Operational Considerations for case management for COVID-19 in health facility and community. https://apps.who.int/iris/bitstream/handle/10665/331492/WHO-2019-nCoV-HCF_operations-2020.1-eng.pdf
  4. Partners in Health. Resource Guide 1: Testing, Tracing, community management. https://www.pih.org/sites/default/files/2020-03/PIH_Guide_COVID_Part_I_Testing_Tracing_Community_Managment_3_28.pdf
  5. CDC. Caring for someone at home. https://www.cdc.gov/coronavirus/2019-ncov/if-you-are-sick/care-for-someone.html
  6. CDC. Using PPE. https://www.cdc.gov/coronavirus/2019-ncov/hcp/using-ppe.html
  7. CDC. Hand Washing. https://www.cdc.gov/coronavirus/2019-ncov/hcp/hand-hygiene.html
  8. Harvard Health Publishing. COVID-19 Basics. https://www.health.harvard.edu/diseases-and-conditions/covid-19-basics
  9. Guan W, Ni Z, Hu Y, et al. Clinical characteristics of Coronavirus disease 2019 in China. N Engl J Med 2020, March 6. DOI:10.1056/NEJM022002032 https://www.ncbi.nlm.nih.gov/pubmed/32109013

 

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!

Key clinical pearls on the management of patients suspected of or diagnosed with Covid-19 in the outpatient setting

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

Is there any evidence that routinely wearing gowns and gloves upon entry into the rooms of patients on contact precautions for MRSA or VRE really works?

Although routine gowning and gloving in the care of hospitalized patients with methicillin-resistant Staphylococcus aureus (MRSA) or vancomycin-resistant Enterococcus (VRE)—also known as contact precautions (CP)— is considered a standard of care (1), the evidence supporting its effectiveness in preventing endemic hospital-associated multidrug-resistant organism (MDROs) infections is not robust and is often conflicting. In fact, this practice is increasingly being questioned (including by some hospital epidemiologists) as means of preventing endemic transmission of MDROs in hospitals (1-7).

Critics often point out that studies supporting the use of CP in MDROs are observational, involving only outbreak situations where they were instituted as part of a bundled approach (eg, improved hand hygiene), making it difficult to determine its relative contribution to infection prevention (2,6).

In fact, recent cluster-randomized trials have largely failed to demonstrate clear benefit of CP over usual care for the prevention of acquiring MRSA or VRE in hospitalized patients (2,4). Furthermore, a meta-analysis of studies in which CP were eliminated failed to find an increase in the subsequent rates of transmission of MRSA, VRE, or other MDROs (2,7).

Based on these and other studies, some have suggested that in the presence of other infection prevention measures (eg, hand hygiene monitoring), CP be implemented only in select circumstances such as open or draining wounds, severe diarrhea or outbreak situations (3).

 

The United States Centers for Disease Control and Prevention (CDC), along with the Infectious Diseases Society of America (IDSA) and the Society of Healthcare Epidemiologists of America (SHEA), however, continue to recommend implementation of CP in the care of patients with MDROs.  

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References

1. Maragakis LL, Jernigan JA. Things we do for good reasons: contact precautions for multidrug-resistant organisms, including MRSA and VRE. J Hosp Med 2019;14:194-6. https://www.ncbi.nlm.nih.gov/pubmed/30811332
2. Young K, Doernberg SB, Snedcor RF, et al. Things we do for no reason:contact precautions for MRSA and VRE. J Hosp Med 2019;14:178-80. https://www.ncbi.nlm.nih.gov/pubmed/30811326
3. Bearman G, Abbas S, Masroor N, et al. Impact of discontinuing contact precautions for methicillin-resistant Staphylococcus aureus and vancomyin-resistant Enerococcus: an interrupted time series analysis. Infect Control Hosp Epidemiol 2018;39: 676-82. https://www.cambridge.org/core/journals/infection-control-and-hospital-epidemiology/article/impact-of-discontinuing-contact-precautions-for-methicillinresistant-staphylococcus-aureus-and-vancomycinresistant-enterococcus-an-interrupted-time-series-analysis/869CD5E44B339770AC771BC06049B98F
4. Harris AD, Pineles L, Belton B, et al. Universal glove and gown use and acquisition of antibiotic-resistant bacteria in the ICU. A randomized trial. JAMA 2013;310:1571-80. https://www.ncbi.nlm.nih.gov/pubmed/24097234
5. Morgan DJ, Murthy R, Munoz-Price LS, et al. Reconsidering contact precautions for endemic methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus. Infect Control Hosp Epidemiol 2015;36:1163-72. https://www.cambridge.org/core/journals/infection-control-and-hospital-epidemiology/article/reconsidering-contact-precautions-for-endemic-methicillinresistant-staphylococcus-aureus-and-vancomycinresistant-enterococcus/CCB41BF48CEC2185CC4D69AF3730584C
6. Morgan DJ, Wenzel RP, Bearman G. Contact precautions for endemic MRSA and VRE. Time to retire legal mandates. JAMA 2017;318:329-30. https://jamanetwork.com/journals/jama/article-abstract/2635333
7. Marra AR, Edmond MB, Schweizer ML, et al. Discontinuing contact precautions for multidrug-resistant organisms: a systematic literature review and meta-analysis. Am J Infect Control 208;46:333-340. https://www.ncbi.nlm.nih.gov/pubmed/29031432

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!

 

Is there any evidence that routinely wearing gowns and gloves upon entry into the rooms of patients on contact precautions for MRSA or VRE really works?