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

Dana G Smith
Elemental

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Photo: Grant Hindsley/AFP/Getty Images

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…

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Dana G Smith
Elemental

Health and science writer • PhD in 🧠 • Words in Scientific American, STAT, The Atlantic, The Guardian • Award-winning Covid-19 coverage for Elemental