Dr. Michael Mina:

We have now seen plenty of people who are vaccinated but carry the virus. Again, I am pretty confident at this time, with the variants circulating today, that the vaccines will prevent disease, especially severe disease. However, we have also seen a lot of data that show distributions of the viral loads are actually not that different between vaccinated and unvaccinated people. We know vaccinated people are likely to be transmitting less because we are starting to see herd effects, meaning when adults are vaccinated we see fewer cases in children. That is a major win.

We need to be very cognisant that we continue monitoring the situation. In my family, for example, which is not an example I usually give but shows how I am thinking, my wife is pregnant and currently has a single dose of vaccine. I will not go into the details of why that is. Even when people who are vaccinated come to our house, we ask them to take a rapid antigen test. That is because we know that people can carry the virus asymptomatically when they are vaccinated, especially things like the Delta variant and the inevitable next variants that will come around.

We just have to very cautious and keep watching the data as they flow in but, at the moment, for travel on an enclosed plane, having pretty tight restrictions is still a good thing. Whether these restrictions are testing everyone before they got on even if they are vaccinated or continuing to use masks, the question of whether they should be used is not a bad question to be asking right now.