If You've Had COVID, How Long Does the Immunity Last? Here's What Medical Experts Say

There's been a lot of discussion lately about natural COVID-19 immunity and how much protection it affords you against reinfection. Even without vaccination, that immunity can provide some level of protection. But does that mean you don't need to get vaccinated if you've already had COVID? Not exactly.

In a new weekly series, "COVID Q&A," NBC10 Boston asked two top Boston doctors on Tuesday for their thoughts on how much COVID antibodies protect against reinfection and how the pandemic is impacting the life expectancy of Americans.

If I already had COVID, do I need to get the vaccine or will antibodies protect me?

The scientific community generally recommends vaccination even in people who have already had COVID-19.

"When you are infected you do generate an immune response to the virus," said Dr. Shira Doron of Tufts Medical Center. "You do have an immunity. Like the vaccine, that immunity isn't perfect."

"You don't want to take your chances with the virus as the way you get your immunity," Doron added. "It's probably inevitable that everyone will meet the virus at some point in the next several years. You want to meet it with as much immunity as possible. You would much rather be vaccinated than naturally infected because of the havoc the virus wreaks on your body and the vaccine doesn't. The vaccines have just been proven to be so safe."

"How the two compare has been difficult to tease out scientifically, partly because different variants generate different types of immune response," Doron said. "Variants in the past may not be as effective as generating immunity as a variant that's circulating now. So if you're hospitalized with COVID you might have a better immune response than if you have asymptomatic or mild COVID. And so it's been very difficult to ascertain how the vaccine and natural immunity compare to each other. What we do know is if you've been previously infected and you get vaccinated that dramatically increases your levels of immunity."

"With an asymptomatic or mild case, the intensity of immune response is less," Boston Medical Center's Dr. Davidson Hamer explained. "Those who were hospitalized may have higher, more intense immunity, but everybody is still at risk for reinfection at some point in the future."

"Adding even a single dose of vaccines to that immunity is a major boost and gives people a very high level of protection," he said.

Is the COVID-19 pandemic impacting the life expectancy of Americans?

Yes, according to Hamer, who said recent analyses have suggested that the pandemic has shortened the life expectancy of Americans. Male life expectancy has decreased by 2.2 years and women by 1.65 years.

"We know from a variety of studies that have been done during the pandemic that men are at higher risk for severe disease and potential death, and I think this is another manifestation of that," he said. "The impact based on these analyses is substantial. It reminds me a little bit of HIV when it ravaged parts of Africa. They had a big drop off in average life expectancy that took years to rebound."

"This is different because we can prevent it with vaccines," he added.

Doron pointed out that the U.S. also reached two grim milestones this week.

"One is that we've lost 1 in 500 Americans to COVID-19, and the other is we've exceeded the death rate of the 1918 influenza pandemic," she said. "So, you know, the devastation is quite significant."

The key to limiting the number of deaths is getting people vaccinated, Hamer said.

"If people are in a part of the country where there are high levels of vaccine abstention, vaccination and preventing infection or preventing severe disease, hospitalization and potential death is the way to go to try and limit any further impact on the potential life expectancy of Americans," he noted.