Op-Ed: Throw Away Your Mask After COVID Vaccination? | MedPage Today

by Vinay Prasad, MD, MPH 

https://www.medpagetoday.com/blogs/vinay-prasad/90764

But I have seen no data that can tell me the added benefit of masks 14 days after vaccination with 95% efficacy. It’s the biological equivalent of asking what happened before the Big Bang. If you ask, what is the evidence that it’s safe to stop wearing a mask, I say, what is the evidence that it’s still beneficial?

This same line of thinking applies to other restrictions that could be eased instead. What evidence supports restricting nursing home visitors, if all parties are vaccinated and masked? What evidence supports banning a small dinner, if everyone has had the vaccine? There is no evidence that supports these continued prohibitions.

Having spent some time thinking about the topic, and discussing with colleagues, I have reached two conclusions. First, it is a tradeoff with residual uncertainties, and reasonable people can disagree. But also, I favor the view that generally, 14 days after vaccination, we can relax some restrictions.

It is important to be upfront with the caveats. Everything I say applies to average people in the community — I am not speaking about enhanced precautions in high-risk settings like nursing homes or medical centers. My argument is contingent on there being no “vaccine escape,” that is, no mutation in the coronavirus that markedly reduces vaccine efficacy.

Finally, my argument is appropriate for most places and most times, but if health systems are overwhelmed, e.g., as we saw in places like southern California or New York City, it might be reasonable to temporarily increase precautions. Additionally, my guiding principle does not apply to businesses, such as grocery stores or pharmacies, which can and will enforce their own policies.”

The data

“The efficacy of the two mRNA vaccines is superb, offering 95% reduction in the rate of acquisition of symptomatic COVID-19 in randomized trials. That is a remarkable result. But the key statistic here is one step beyond the vaccine efficacy. If you get two doses of the vaccine, and if you remain asymptomatic 14 days after the second dose, what is the probability you will develop COVID-19? For Moderna, the answer is there is a 99.92% chance that you won’t. Only 12 cases occurred after this time in 14,550 actively vaccinated people in the trial, while the control arm experienced nearly 3.5% cumulative incidence. For Pfizer, only eight cases occurred amongst people who had completed a second dose and went 7 days without symptoms, again a 99.95% chance of not getting COVID if one remained asymptomatic a week after the second dose. In other words, if you get 14 days past the second dose, and feel fine, the likelihood you will get COVID-19 in these studies is very low. Some argue that in the real world — where folks are not as motivated as trial participants — the rate of SARS-CoV-2 acquisition might be higher, and thus relaxing rules riskier. But this logic cuts both ways: if people in the real world are less compliant, then the rules might be relaxed no matter what we say.

Risk of spreading is diminished by the brisk immune response that occurs after symptomatic infection once someone is vaccinated. In the Moderna study, there were 30 cases of severe COVID overall and zero in the vaccination arm. Less symptomatic and less severe COVID will result in a lower propensity to propagate SARS-CoV-2. Moreover, studies of both recombinant antibody products speed viral clearance from airways. If the body is primed to manufacture anti-spike antibodies through vaccination, there is likely a similar rapid clearance and subsequent reduction in infectiousness occurs.

What about asymptomatic infection and so-called silent spread? In the Moderna trial, swabs taken from asymptomatic participants as they were receiving dose 2 showed a roughly 60% reduction in PCR positivity. It is likely that a second dose and longer asymptomatic period will result in greater reduction in PCR positivity. Preliminary data from AstraZeneca’s ChAdOx1 vaccine also showed reduced in asymptomatic PCR detection. In short, it is highly likely that receipt of vaccination and a 14-day asymptomatic period afterward results in both personal protection and reduced likelihood of ongoing viral propagation.

Knowing these three facts allows us to put it all together. Is it reasonable to tell someone that, if they are asymptomatic 14 days after the second vaccine, they are highly unlikely to get COVID-19, and also less likely to spread the virus — both by having less severe disease, less asymptomatic carriage, clearing virus faster, stronger antibody responses, and fewer symptomatic cases? Absolutely, is my view.

The politics/sociology

Public health experts have reminded me to talk about despair. We are all facing it, and when you clamp down on a society with restrictions, a free society can only bear it for so long. There must be a path out of it, and easing restrictions — particularly when the burden may outweigh the unproven, theoretical, and at best highly marginal benefit — is a great way to renew optimism. Folks who spend time doing boots on the ground public health share their view with me that this is a great place to start.

Source: Op-Ed: Throw Away Your Mask After COVID Vaccination? | MedPage Today

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