April 5th-6th Covid-19 Literature Review

Steven Kornweiss, MD covid-19 Leave a Comment

Masks

An article was published today in Annals of IM Titled: "Effectiveness of Surgical and Cotton Masks in Blocking SARS–CoV-2: A Controlled Comparison in 4 Patients."

The first line of the discussion section says:

"Discussion: Neither surgical nor cotton masks effectively filtered SARS–CoV-2 during coughs by infected patients."

But, let’s take a look at the data collected from the 4 patients enrolled in the study:

The numbers are in log copies per mL and ND means (not-detected). This means that the inside of the masks seems not to have virus on them, the outside does, and a petri dish with viral medium held 20cm from the patient’s mouth while they’re coughing grows virus whether they’re wearing a surgical, cotton, or no mask.

If true, these results suggest we have a lot to learn about masks, physics, and viral media. Whether true or false, these results should not be used to conclude that wearing surgical masks in public does not decrease transmissibility of this disease.

But, unfortunately, this is the Tweet put out by the Annals of Internal Medicine:

"NEW in Annals: Both surgical and cotton #masks were found to be ineffective for preventing the dissemination of SARS-CoV-2 from the coughs of patients with #COVID19 http://ow.ly/17aa50z6SLu."

Notice the tweet uses the word "dissemination" instead of "transmission." Dissemination just means that virus leaves the inner container of the mask. Transmission refers to transmissibility of the actual diseaes. Notice also the choice of "SARS-CoV-2," which is the name of the virus, as opposed to "Covid-19," the name of the disease. This study only shows that virus can be cultured from masks and from the area immediately in front of mask wearers when viral media is placed within 20 cm. The study does not do anything to tell us that masks are ineffective at decreasing transmission.

Immunosuppression

It’s not a foregone conclusion that individuals with immunosuppression are at higher risk for critical illness or death from Sars-CoV-2 infection. There are some who believe that immunosuppression may in fact prevent some of the severe lung injury that is the cause for respiratory failure in Covid-19.

This article draws a connection between blood work, lung pathology, and disease outcomes. It’s been known from early publications out of China that patients with Covid-19 often demonstrate lymphopenia. This is determined by one of the simplest, cheapest, and most ubiquitous tests that we send on almost every patient who comes to the hospital, a CBC (complete blood count).

The lymphocyte is a type of white blood cell, and in Covid-19 patients, these are often found in lower amounts in the blood. One theory is that the lymphocytes are no longer in the blood stream because they’ve invaded damaged organs (such as the lungs). Autopsies and lung biopsies from patients with Covid-19 show lymphocytes infiltrating the lung tissue.

What’s more, some case series have found that the more severe the lymphopenia, the more likely a patient will have respiratory failure, critical illness, or death. Some immunosuppressive drugs may decrease the reactivity of the lymphocytes to viral infection. The virus can still damage the cells, but without the additional damage of the immune system, perhaps some patients escape secondary immune mediate damage. This is the basis for a theory of including immunosuppressant drugs on the list of things to consider for Covid-19.

The major downside to this idea is that it could open the patient to secondary infections. We have seen some studies show that patients with respiratory failure from Covid-19 may have a higher chance of becoming critically ill or dying if they have a coinfection – viral or bacterial. Corticosteroids, another class of drugs that are generally thought of as immune suppressants have also been shown under certain circumstances to potentially worsen Covid-19 outcomes.


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