The first vaccinations for the coronavirus have begun: In the United Kingdom, high—risk populations and front—line healthcare workers are being given a vaccine developed by BioNTech and Pfizer.
Meanwhile, the Food and Drug Administration (FDA) is expected to meet this week to determine whether the vaccine will be given an emergency use authorization in the United States; another candidate, developed by Moderna, will be decided on next week.
While vaccine delivery is expected to be complicated, it's estimated that tens of millions of Americans will be inoculated against the coronavirus in the coming months. However, experts warn that getting a vaccine won't immediately eliminate the need for mask-wearing and other safety measures.
"The COVID vaccine, or at least the (candidates) that we have right now, require two doses to be fully effective," explained Dr. David Dowdy, an epidemiologist and associate professor at the Johns Hopkins Bloomberg School of Public Health. It's believed that the Pfizer and Moderna vaccines are both more than 90% effective after both doses; yesterday, it was announced that the Pfizer vaccine is about 50% effective after just one dose. "Until you get that second dose, you shouldn't consider yourself protected."
Dowdy said that the rollout of the vaccines, which will take at least several months and likely not apply to the general population until the spring, also means that safety precautions are important.
Krystal Pollitt, Ph.D., an assistant professor of epidemiology at the Yale School of Public Health, said that there are still some unanswered questions: While the vaccines seem to prevent people from getting the disease, it's unclear if people can still be infected and transmit the virus to unvaccinated people.
"They may be potentially asymptomatic, with low levels of virus in their systems, and be able to spread the virus to others, even if they are vaccinated," she explained. "The second problem is that it doesn't prevent infection 100%. There's that 5% potential for infection."
While a 5% potential for infection may not sound high, in a situation like the United States is currently facing — where the virus is raging and cases are being diagnosed at record-breaking rates — Dowdy cautioned that it could still mean many cases of the illness until enough of the population is vaccinated that the virus subsides.
"I think it's important to continue wearing masks," Dowdy said. "People who have gotten the vaccine should be operating in much the same way as people who have not had the chance to get the vaccine, as far as trying to slow the spread of transmission of the disease."