The views and opinions expressed here are those of the authors and do not necessarily reflect the position of either Johns Hopkins University and Medicine or the University of Washington.
The potential severity of COVID-19 continues to stagger the imagination. Data collected over the past year grimly prove that early assertions calling COVID-19 simply the flu were false. A graph recently shown in the New York Times illustrates my point:
It’s this knowledge that I carry with me from day to day as a reminder: “Larry, you’re vaccinated, but a lot of people aren’t. In fact, 90% of the people walking around are not vaccinated and you do not have the luxury to give up your responsibility to protect them.”So, this issue of mask wearing? Once you’re vaccinated, it’s really not about you at all. It’s about the other person. Maybe a friend or family member or neighbor or colleague that attends the same event or gathering but has not had the opportunity to be vaccinated. Or even someone who has chosen not to be vaccinated: do they deserve to get ill?
One might ask, a year into this pandemic, why don’t we know whether being vaccinated will prevent transmission? We don’t know this because the kinds of studies required to look at transmission are different from the ones designed to test vaccine efficacy. The clinical trials testing vaccine efficacy showed personal benefit – in other words, if you get vaccinated, will you be protected? And the answer to that as we’ve seen is yes, for all three of the vaccines currently authorized for use and being distributed in the U.S. But looking at transmission is a different matter altogether.
In the phase 3 trials there were thousands and thousands (approximately 30,000 participants) who were tested regularly (approximately once a week) to see if they got symptomatic COVID-19. But to test whether the virus was colonizing in the nose would have required near-daily testing. And if you pause to consider that – 30,000 persons over five months – with each person coming in daily to get their nose swabbed, it would have become impossible to test all the cultures in a timely way. We would have been diverted from defining vaccine efficacy.It is possible to take fewer people and do what we call a transmission study, which is currently being conducted with the mRNA vaccines. We will look at vaccinated versus unvaccinated persons and determine if vaccination prevents you from transmitting the virus. This will require intensive contact tracing – looking at the contacts, who got infected, who didn’t? Who came first; who came second? Can we define exactly this person got it from that person? Sometimes the genetics of the virus allows one to do that. The emerging variants also complicate things because they have been shown to be more infectious. For example, the B.1.1.7 strain first seen in the UK has been shown to cause 30% more infections. It appears to be shed for a substantially longer period of time than the G614D strain, which makes it more infectious. As the virus adapts, these new strains will cause a stress on vaccinations. But I think we can almost be happy that we’re doing the transmission study during the period of time when the virus is changing because we really do get at the relevant issue of how well these vaccines perform when the virus is starting to mutate. So, we are getting to answers, but it will take some time. With a little luck, the transmission study will show the mRNA vaccines are spectacular at working to prevent COVID-19 altogether. Or if you do acquire it, the viral loads are trivial, and you won’t transmit it to anyone else. I’m hoping that’s the result because I want to take off my mask. But until we know this with reasonable certainty, or at least until more of our population is vaccinated, then public policy – and individual conscience – should mandate mask use in public spaces and any but small gatherings in our homes. The CDC guidance is clear that fully immunized people can meet each other at home, in small groups, without mask wearing and social distancing, but we’re going to have to maintain vigilance in public spaces, at work, on public transport, and at schools as they reopen. Mathematical modeling shows that without adhering to these measures, we could double the deaths. How each one of us behaves makes a difference. Together, we can markedly influence the surges associated with this virus and potentially save lives.