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Experts warn that immunity from prior COVID-19 infections will wane, urge vaccinations

A man received his Moderna COVID-19 vaccination booster at the Whittier Street Health Center.Pat Greenhouse/Globe Staff/file

Don’t count on getting lasting immune protection if you have endured a case of COVID-19, experts are warning, saying the best bet is to get vaccinated.

Dr. Ashish Jha, dean of the Brown University School of Public Health, said on Twitter Sunday that infection-induced immunity is “real” and “helpful” but “doesn’t really seem to last that long.”

He said it “almost surely” prevented infections and hospitalizations for about 90 days. “Beyond that? probably not that much,” he said.

He urged people to get vaccinated to “avoid all the heartache and misery of having to get infected over and over again.”

The large number of people who have been infected with the coronavirus during the rise of the Omicron variant has raised hopes that widespread immunity, provided by both the infections and by vaccinations, will suppress the virus - at least for a time, if not to the point that the pandemic is under control.

But people who get COVID-19 shouldn’t think they can skip getting vaccinated, experts say. The US Centers for Disease Control and Prevention says people who have had a bout with COVID-19 get “some protection” from the virus but it may vary depending on the person - and people should still get vaccinated to ensure a high level of protection.


Dr. Scott Gottlieb, former director of the US Food and Drug Administration, said Wednesday on CNBC-TV, “What we saw with previous variants was that the immunity persisted for a longer period of time. What we are seeing with Omicron, and there is now pretty good evidence around this ... it appears that the immunity conferred by infection from Omicron isn’t that durable.”

“You probably have a period of immunity that lasts at least three months, probably upwards of six months. But eventually the antibodies do wane,” said Gottlieb, who is also a Pfizer board member.


He said that prior infection would “probably” protect against “more severe outcomes ... but you’re probably going to get subsequently infected or reinfected with Omicron.”

“It’s certainly going to be sufficient to provide a level of immunity for us as a population, given how many people we’ve seen infected with Omicron, to drive prevalence levels down very low,” he said.

Heading into the fall, he said, people who have already been vaccinated may need to get another shot “if you want to maintain your immunity.”

William Hanage, an epidemiologist at the Harvard T.H. Chan School of Public Health and a co-director of its Center for Communicable Disease Dynamics, said the amount of immunity building up in the population through infection and vaccination, may make future surges less severe.

“At some point, you know, almost everybody is going to be having some encounter with the virus, and the immunity that will result from that is going to mean that the next time they see the virus they’re less likely to be ill, severely ill,” he said on the “In the Bubble” podcast hosted by former White House pandemic adviser Andy Slavitt.

“Now, I will point out that ... the way to get that immunity is not to get infected,” he said. “The ideal way to get that immunity is to be vaccinated because you’re then acquiring the immunity without the risks of infection and without something that you can transmit to other vulnerable folks. So get vaccinated.”


Hanage said on the podcast one thing to watch is what happens in Florida this summer. Cases have surged there in the past two summers and a key question is whether the immunity from previous Omicron and Delta infections plus the state’s vaccinations will be enough to prevent a severe outbreak.

“I think that we’re likely to see waves of cases in Florida, certainly. The consequences of those cases in terms of hospitalizations etc. are going to be to be really useful to us to understand what we might expect in the fall and winter,” he said.

Martin Finucane can be reached at