MIT Medical answers your COVID-19 questions. Got a question about COVID-19? Send it to us at CovidQ@mit.edu, and we’ll do our best to provide an answer.
I have a friend who survived COVID-19 back in December 2020. I remember speaking to him on the phone when he was self-isolating. He was coughing so much that he couldn’t even talk. Now he keeps asking when he can come visit. He says he doesn’t need to get vaccinated, but I think he should get vaccinated just like everyone else if he wants to visit friends. Am I right?
Yes, you are right. According to CDC guidance and everything we know of the science, your friend absolutely should be vaccinated. That’s because we have been able to confirm that people who have recovered from COVID-19 can become reinfected. While current evidence suggests that reinfection doesn’t usually occur during the first couple of months after recovery from COVID-19, the risk of reinfection increases with time, as natural immunity decreases. New viral variants may increase the risk of reinfection even more.
Recent research from China demonstrates the danger of depending on natural immunity. In this study, published last month, researchers looked for antibodies against SARS-CoV-2 in blood samples taken from more than 9,000 people in Wuhan, the original COVID-19 epicenter, over the course of almost nine months — first in April 2020, after the city’s lockdown was lifted; then again in June; and, finally, between October and December. The team found that about seven percent of the population had been infected with the virus at some point, but fewer than 40 percent of recovered individuals produced “neutralizing antibodies” — antibodies capable of preventing reinfection. Their conclusion? Even Wuhan cannot reach herd immunity and prevent a resurgence of the epidemic without mass vaccination.
Your friend should get his vaccination as soon as he is eligible. In general, CDC guidelines allow someone who has tested positive for COVID-19 to get vaccinated as soon as they have recovered from their illness (if they had symptoms) and/or once they’ve met criteria for discontinuing isolation. The only exception is for individuals who were treated with passive antibody therapy — monoclonal antibodies or convalescent plasma — while they were ill. Because that kind of treatment can interfere with the body’s immune response to the vaccine, those individuals need to wait at least 90 days before they can get vaccinated.
Getting vaccinated has benefits for vaccinated individuals, of course, but it may also help to protect entire communities, including children, who are not yet eligible for vaccination. For example, a recent Israeli study of 223 communities found that in the weeks after older people had received the Pfizer–BioNTech vaccine, the infection risk among children under 16 in the same community dropped in direct proportion to the percentage of adults who had been vaccinated.
You don’t mention if your friend has suffered any lasting effects of his bout with COVID-19, but there are some indications that vaccination may have the unanticipated benefit of providing relief for “long-haulers” — the up to 30 percent of individuals who suffer lingering symptoms of COVID-19 illness, frequently referred to as “long COVID.” Much of the evidence for the benefits of vaccination in this group remains anecdotal. However, a small, not-yet-peer-reviewed U.K. study found that roughly 23 percent of long-haulers experienced an “increase in symptom resolution” after vaccination, compared with only about 15 percent of those who remained unvaccinated.
We’ve all spent the last year dreaming about a return to normal life, and the vaccine is one of the most powerful tools to get us there. But vaccination is not only a means of ensuring strong immunity, reducing lingering symptoms, and protecting others; it can also give your friend the peace of mind that comes from knowing that he almost certainly will never to have to go through severe COVID-19 illness again. We hope that you’ll encourage your friend to get vaccinated when he can and that the two of you are able to enjoy a safe and happy visit in the not-too-distant future.