Once you get the vaccine (or a natural infection), it’s really important you continue to wear a mask, social distance, wash hands, etc. Let me (try to) explain.
We know the Pfizer and Moderna vaccine protects you (ie the person that gets the vaccine) against disease. We know this from the high efficacy numbers (95%) and our antibody studies thus far (see previous posts). In other words, if you get the vaccine and come in contact with COVID19, your body will know how to fight the virus and your immune system doesn’t get overwhelmed and go crazy (ie fever, respiratory issues, and potentially the ICU).
We do NOT know whether a vaccinated person (or person with a previous covid infection) can still host the disease and continue to spread it. In other words, if you get the vaccine and come in contact with COVID19, you MIGHT be able to still harbor the virus. Then, if you come into contact with someone else who doesn’t have the vaccine, you give them the virus. This is worst case scenario. We HOPE that we have sterilizing immunity, in which the COVID19 antibodies protect from both disease (ie symptoms) AND transmission. We just don’t know yet.
Since people asked yesterday, not all vaccines produce sterilizing immunity, but they don’t need to in order to be effective at preventing disease (i.e. symptoms and illness). For example, the polio vaccine does not induce a sterilizing immune response but is still 90% effective. On the other hand, the HPV vaccine does prevent transmission.
Moderna is testing whether we have sterilizing immunity after the COVID19 vaccine. They do this by testing everyone for COVID19 every few weeks (instead of just symptomatic people) AND they do this by testing for a unique antibody called a neutralizing antibody. So far, there are two small hints that we may have sterilizing immunity after a vaccine:
- In the middle of their trial (called an interim analysis), Moderna tested 34 people for neutralizing antibodies over time. 119 days after the vaccine, everyone still had these antibodies. The number of neutralizing antibodies decreased a little, but that’s expected. These results were published in the New England Journal of Medicine (the most predominant journal in medicine)
- In the FDA Moderna report yesterday, another small hint was reported. While Moderna’s full analysis wasn’t complete, they wanted to give a glimpse of the data so included it in their addendum (ie not the full report for their application for emergency use). Moderna reported that 38 people in the placebo group had asymptomatic infection while 14 in the vaccine group had asymptomatic infection. This is an indirect, proxy analysis. It’s certainly not as good as testing antibodies, but is a hint.
These are small studies. And, like everything else, we need more data. We want to be sure that these findings are meaningful (and not random). Moderna is working on it. Unfortunately, though, it will be a few months until we know more.
So, in the meantime, continue public health mitigation measures if you do get infected or get the vaccine. We can’t have a mask bonfire yet.
Moderna addendum: https://www.fda.gov/media/144453/download