Could current COVID vaccines protect against future outbreaks?

Before March 2020, it was hard to imagine a global pandemic in the modern age.

Now, it’s hard to imagine our lives without one.

As COVID-19 has become less of an active part of our days and more a quick thought when we have a runny nose or cough, it’s time to think about what comes next — and how to stop another pandemic.

A group of researchers had just that in mind when they asked if current COVID-19 vaccines and boosters could protect your body against future outbreaks. Their findings were published this month in the journal Nature.

Here’s what you need to know:

What is immune imprinting?

Researchers from Washington University’s School of Medicine in St. Louis evaluated the ability of COVID shots to build up memory in the immune system through a process called immune imprinting.

“Immune imprinting is a phenomenon in which prior antigenic experiences influence responses to subsequent infection or vaccination,” according to the study.

This means that when the human body is exposed to an infection, whether by becoming infected or receiving a vaccination, the immune system can build up defenses against it, and those defenses stay in the body even when the infection has left.

“Imprinting is the natural result of how immunological memory works. A first vaccination triggers the development of memory immune cells,” researchers said in a news release from Washington University. “When people receive a second vaccination quite similar to the first, it reactivates memory cells elicited by the first vaccine. These memory cells dominate and shape the immune response to the subsequent vaccine.”

But since your body holds onto some “immunity,” it can make it difficult to create a vaccination for the following year that complements an already established immune response and doesn’t interfere.

Doctors already have to deal with this problem.

The annual flu vaccine is updated and adapted each year before the fall rollout to best target the strains of influenza that are particularly strong or infectious.

“In the case of the flu vaccine, imprinting has negative effects,” according to the release, and the cells that are supposed to produce antibodies to fight the virus instead crowd other antibody-producing cells, making the vaccine less effective.

The worry is that if people receive annual COVID-19 boosters, like health officials recommend for influenza, immune imprinting could make the population vulnerable when a new coronavirus, or even another similar virus, starts to spread again, the researchers said.

Their results tell a different story.

‘Gradually build up a stock’

Researchers measured antibodies in people who had all of the updated COVID shots to see if their neutralizing antibodies came from the original variant from the first shots, an omicron variant from updated shots, or both.

They found that most people had antibodies that weren’t unique to the original variant or omicron, meaning the antibodies could also protect against similar strains that haven’t been identified, according to the release.

“The study … shows that people who were repeatedly vaccinated for COVID-19 — initially receiving shots aimed at the original variant, followed by boosters and updated vaccines targeting variants — generated antibodies capable of neutralizing a wide range of SARS-CoV-2 (the virus that causes COVID-19) variants and even some distantly related coronaviruses,” researchers said in the release.

The “cross-reacted” response also extended to far-reaching relatives of COVID-19, such as the Middle Eastern Respiratory Syndrome, a coronavirus that was first reported in 2012.

Instead of getting in the way of the body’s natural ability to identify and respond to new variants, periodic re-vaccination against COVID-19 may “instead cause people to gradually build up a stock of broadly neutralizing antibodies that protect them from emerging SARS-CoV-2 variants and some other coronavirus species as well, even ones that have not yet emerged to infect humans,” according to the release.

This assumes, however, that a person maintains the shot regimen recommended by health officials.

COVID vaccination guidelines

As of May 14, the Centers for Disease Control and Prevention recommends that everyone over the age of 5 receive one dose of the updated COVID vaccine, whether they receive initial doses or not.

This includes the Pfizer-BioNTech, Moderna and Novavax shots.

Children between the ages of 6 months and 4 years old may need more than one dose to be up to date, including the newest 2023-24 shots.

People with immune concerns or who are older than 65 should receive one dose of the new shot, as well as an additional spring shot with at least 4 months in between the two, the CDC says.

It is safe for people who are pregnant or who plan to become pregnant to receive updated doses.

If you are experiencing symptoms of COVID — including but not limited to cough, fever, chills, nausea, vomiting, diarrhea, fatigue and muscle aches — remain isolated until you have gone at least 24 hours without a fever without taking any fever-reducing medications and your symptoms are improving overall, the CDC says.