Answering clinical questions about COVID-19

In this EBM Focus article, the DynaMed team answers ten frequently asked questions about coronavirus disease 2019 (COVID-19). EBM Focus articles provide concise summaries of clinical research most likely to inform clinical practice.

The COVID-19 pandemic is an evolving situation with rapidly changing information. The answers to these questions are accurate as of April 30, 2020.

1. Once a person has recovered from COVID-19, can they get it again?

While it’s clear that patients infected with COVID-19 develop antibodies to the virus, it remains unclear how long the protection lasts. Very early research in macaque monkeys has shown short-term immunity in primates, but this data has not been peer-reviewed yet. Looking at data from survivors of epidemics like SARS (case fatality 11%, 2002) and MERS (case fatality 39%, 2012) may help us develop a vaccine. Coronaviruses are RNA viruses that mutate rapidly, raising concern that immunity may be temporary (this is the reason why we need yearly flu vaccines).

2. Many of my patients are asking about cloth masks. What can I tell them about how they compare to surgical masks?

There is little evidence evaluating the use of cloth masks with respect to COVID-19 (estimated size 0.12 microns) specifically. Homemade cloth masks (without filters) may prevent the transmission of some particulate matter but were much less effective than manufactured surgical masks at preventing transmission of influenza. There is some evidence that certain materials are more helpful than others, however, and perhaps a cloth mask with vacuum bag filter could approximate the efficacy of a surgical mask if it came to that. While these types of masks may not protect the wearer to any significant extent, they may decrease the spread of the virus from asymptomatic persons and limit touching of the face.

3. Is it true that COVID-19 transmission will decline with warmer weather?

There is no evidence about whether warm weather will decrease COVID-19 cases, but cases are increasing exponentially in areas of the world that are currently experiencing higher temperatures, such as the American South and Africa. On the other hand, MERS transmission was shown to be partly exacerbated by cold windy weather, and seasonal factors beyond temperature (such as traditional holidays) have been hypothesized to exacerbate the current COVID-19 outbreak.

4. Should mothers stop breastfeeding if they have symptoms or test positive for the virus?

Although we do not know all the facts about how SARS-CoV-2 is spread, it does not appear to be present in breastmilk. Mothers with known SARS-CoV-2 infection or who are under investigation should take extra care when breastfeeding, including washing hands, wearing a mask and consider covering the baby with a blanket or towel.

5. Does a negative test rule out a SARS-CoV-2 infection?

Keep pretest probability and prevalence in mind when interpreting the results of COVID-19 testing. Unless the sensitivity of a test is 100% (and current estimates for SARS-CoV-2 are in the 70-80% range), if prevalence is high and likelihood of disease high, a negative test cannot rule out disease. The possibility of a false negative result should be especially considered if the patient’s recent exposures and clinical presentation indicate that COVID-19 is likely. Given the limitations on testing that have been present, the true prevalence of COVID-19 infection is almost certainly an underrepresentation.

6. Should patients with COVID-19 continue taking their ACE inhibitors or ARB medications?

SARS-CoV-2 does use angiotensin converting enzyme 2 (ACE2) receptors to enter respiratory and cardiac cells. Although animal models showed changes in ACE2 expression with ACE inhibitor and ARB use, there are no clinical studies reporting outcomes related to use of these medications. The AHA/ACC currently recommend continuing ACE inhibitors and ARBs given their proven cardioprotective benefits. In addition, there are proposals to use ARBs as a potential co-treatment for COVID-19.

7. Can patients take ibuprofen safely if they have a COVID-19 infection?

Although bench science suggested that nonsteroidal anti-inflammatory drugs (NSAIDs) may increase ACE2 expression, the currently available evidence suggests ibuprofen and other NSAIDs are safe during COVID-19 infection. Despite initially recommending against NSAIDs, the World Health Organization rescinded that statement and the Public Health Agency of Canada, along with other organizations, continue to recommend this class of drugs for symptomatic and anti-pyretic therapy.


For more answers please visit our FAQ section here.

Source: Canadian Medical Association, accessed May 1,2020

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