When To Get Boosted After Having a COVID-19 Breakthrough Infection

If you just tested positive for COVID-19 but haven't been boosted yet, should you run to your local pharmacy and get a booster shot once you're well? After all, universities and employers across the country can require proof of boosters before allowing you to return to campus or the office.

The official guidance from the Centers for Disease Control and Prevention (CDC) is to delay your booster by three months from when your symptoms started or, if you had no symptoms, when you received a positive test.

According to the CDC, getting a COVID-19 vaccine after you recover from COVID-19 infection provides added protection against COVID-19.

In September 2022, White House COVID-19 response coordinator Dr. Ashish Jha confirmed that people who recently caught COVID-19 or were recently vaccinated could wait a few months to get a new Omicron booster.

We asked experts to parse out what we know about booster shots after a breakthrough infection.

Do You Really Need a Booster After a COVID-19 Breakthrough Infection?

Let's look at the rationale for boosting. "I always like to remind people what the word 'booster' means," said Michael Bauer, MD, medical director at Northwestern Medicine Lake Forest Hospital in Lake Forest, Illinois. "It reminds your immune system to rev up again [to produce more antibodies]," Dr. Bauer told Health.

"If you've been vaccinated and then get a COVID infection, that infection is actually serving a similar role to a booster," Dr. Bauer explained. "In effect, you are getting a booster at that point by natural immunity."

The question is, how long does that immunity last?

Data from earlier in the pandemic suggest that people are unlikely to get reinfected right away. One study, published in JAMA Internal Medicine, looked at people who had COVID-19 (confirmed by an antibody test) on or after January 2020. Researchers followed those people over time. The likelihood of getting another COVID-19 infection within 90 days was exceedingly low.

That's because we develop antibodies to help fight off the virus, according to Dr. Bauer.

Once the Omicron variant became dominant (Omicron was the variant of concern in September 2022 according to the CDC), protection conferred from previous infection became unclear. However, studies started to weigh in.

According to a July 2022 study published in the New England Journal of Medicine (NEJM) by Weill Cornell Medicine in Qatar, people who received two doses and caught COVID-19 had more than 50% protection against infection. The study also found that people who received three shots with the original vaccines and then caught COVID-19 had more than 70% protection against infection from the Omicron BA.1 and BA.2 subvariants.

The NEJM study concluded that vaccination enhanced protection among persons who had a previous infection and that hybrid immunity (resulting from previous infection and recent booster vaccination) offered the strongest protection.

One of the reasons why hybrid immunity may be most protective could be related to variability in the immune response. "I think one of the problems with natural infection is that the antibody responses that you're going to get, and the immune responses that you are left with after natural infection, can be variable," said Jonathan Li, MD, associate professor of medicine at Harvard Medical School and a member of the NIH COVID-19 Treatment Guidelines Panel.

"We just don't know how well that recent infection is going to protect that individual against subsequent infection, whereas a booster is standardized," Dr. Li told Health during a media briefing on COVID-19. Vaccinations (including boosters) are also a "more reliable means of offering longer-term protection," Dr. Li noted.

Who's Eligible for a Booster After Having COVID?

Adults and some adolescents are eligible for booster doses. Updated boosters, also known as bivalent boosters, target the Omicron subvariants, known as BA.4 and BA.5, in addition to the original SARS-CoV-2, according to the CDC.

Here's how the CDC breaks out its booster guidance:

• People ages 5 years to 11 years are currently recommended to get the original (monovalent) booster.
• People ages 12 years and older are recommended to receive one updated Pfizer or Moderna (bivalent) booster.

To help you understand if and when you can get boosters based on your health, health status, and previous COVID-19 vaccine immunizations, the CDC has a COVID-19 booster tool you can use. The tool can help you determine when or if you (or your child) can get one or more COVID-19 boosters.

What if You Are Required To Get a Booster Even Though You Had a Recent COVID-19 Infection?

Per CDC guidance, people who had COVID-19 before getting their booster dose should go ahead and get that extra jab by 3 months post-infection for better protection. But don't delay beyond that.

A June 2022 NEJM study found that protection against reinfection decreased with time among people previously infected with COVID-19 (regardless of whether they had received any dose of vaccine or whether they had received one dose before or after infection). The study also found that a single dose of vaccine after infection reinforced protection against reinfection.

As long as a person is eligible for the booster, age isn't a factor, said Michael Chang, MD, a pediatric infectious disease physician with McGovern Medical School at UTHealth Houston and Children's Memorial Hermann Hospital. "As long as you're eligible for the vaccine and booster, the guidance is the same," Dr. Chang said.

A Quick Review

It's important to keep up to date on vaccines and boosters for the best protection. According to the CDC, people who already had COVID-19 and do not get vaccinated after their recovery are more likely to get COVID-19 again than those who get vaccinated after their recovery. So once it's been three months since you've had COVID-19, it's time to schedule that booster appointment.