Scientists Are Optimistic That the Vaccine Will Partially Prevent Infection
The data are still out, but scientists say those who are immunized will likely shed less virus than those who aren’t
The vaccines are here, they’re safe, and they’re extremely effective at preventing both mild and severe cases of Covid-19. But whether a vaccinated person could still become infected with the SARS-CoV-2 virus and pass it on to other people is another question, one the public and scientists alike are desperate to know the answer to.
Experts say that the virus could still enter cells in a vaccinated person’s nose and mouth and begin to replicate there. The immune response generated by the vaccine would quickly defeat the virus, so the infection wouldn’t last long, and the virus likely wouldn’t be able to get down into the lungs where it can wreak havoc. But the asymptomatically infected person could still unwittingly transmit the virus to other people, especially those who are not yet protected.
A study published earlier this week about the AstraZeneca vaccine, which is not yet approved for use in the United States, provided the first look at data collected explicitly to answer this question. The research showed a 67% reduction in infections after two doses of the vaccine, as well as an 82% drop in cases of symptomatic disease. Other studies that will provide information on the two vaccines currently authorized in the United States, produced by Pfizer/BioNTech and Moderna, are expected in the coming months.
As the vaccine rollout is ramped up across the country, people need guidance on how to behave now, so Elemental asked five scientists and physicians how they expect the vaccines will perform when it comes to transmission. Based on what they know about other vaccines and the data currently available from research in animal models, all six experts said they expect the vaccines will partially prevent the spread of SARS-CoV-2, but they likely will not provide so-called “sterilizing immunity” — complete protection against not only symptomatic disease but also infection with the virus.
The Pfizer/BioNTech and Moderna vaccines offer roughly 95% protection against Covid-19 after two doses. This means that only 5%…