- Updated COVID-19 booster shots are available and recommended for most people ages 5 and older.
- The CDC recommends not getting vaccinated or boosted against COVID if you're ill with the virus.
- It's not necessary, however, to test for COVID before you get a shot, unless you are feeling ill.
Updated COVID-19 boosters are now available and recommended for most people ages 5 and older, as long as its been at least two months since their final primary series dose, or one of the previously-recommended monovalent boosters.
But if you’re actively sick with the virus—either with symptoms or by a positive test—the Centers for Disease Control and Prevention (CDC) recommends not getting a COVID booster until after your isolation period is finished. In fact, you may wait up to three months after having COVID to get your booster dose.
This all begs the question: If you shouldn't get a COVID booster while you're sick, should you take a COVID test to make sure you're in the clear to get the shot?
It turns out, the answer here isn't so clear-cut, and depends largely on the presence of symptoms. Here's what to know about whether it's necessary to test before your COVID booster, and why health officials recommend waiting until you're no longer sick to get boosted.
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Testing Before a Booster: Only Necessary With Symptoms
Nearly three years into the pandemic, it's well known that COVID can sometimes present as asymptomatic. But if you're not experiencing any of the telltale symptoms—fever, cough, fatigue, headache—it's not necessary to test before you get a booster dose.
“Asking people to consider testing themselves before they get vaccine, I would worry creates a barrier,” William Schaffner, MD, professor of infectious diseases at the Vanderbilt University Medical Center, told Health. “And that’s certainly not recommended by the CDC.”
But if you are feeling under the weather, testing for COVID is a good idea, regardless of whether you have a scheduled booster shot or not.
"If you're sick, get yourself tested," said Dr. Schaffner. "And sick will depend upon individuals—how much of a runny nose, feeling fatigue, sore throat, mild cough will precipitate your getting tested."
Because everyone may differ in feeling sick, a good rule of thumb may be to rely on the presence or absence of a fever. If you feel mildly ill, but don’t have a fever, you may still be able to get the shot. But if you have a fever, it may be the sign you need to delay your upcoming dose.
When you’re sick—especially with an elevated temperature—your body mounts an inflammatory response to help fight off the illness, “and so you don’t want to get that mixed up with vaccine,” Pedro Piedra, MD, pediatric infectious disease specialist and professor of molecular virology, microbiology, and pediatrics at the Baylor College of Medicine, told Health.
If your body were to encounter a vaccine while it was already fighting off another illness, it could cause greater reactogenicity, or the vaccine’s ability to elicit an inflammatory reaction from the body, like fever or injection-site pain, said Dr. Piedra.
Your body—specifically its white blood cells—may also get confused if it’s tasked with fighting off an illness and mounting an antibody response from a vaccine. That could lead to a weaker vaccine response. But neither of those two situations is necessarily dangerous.
Ultimately, the recommendation not to get vaccinated while already ill is an attempt by health experts not to make people feel any worse than they have to—and to avoid more vaccine hesitancy.
"We don't like to try to get things confused between an underlying illness and a vaccine," said Dr. Piedra. "Because then oftentimes the vaccine gets a bad rap."
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Waiting Longer for a Better Vaccine Response
While you can technically get a COVID booster after you've ended your isolation period following an illness, you may want to wait a bit longer to give your body an even better fighting chance.
"A somewhat longer interval is actually beneficial," said Dr. Schaffner.
The CDC’s Advisory Committee on Immunization Practices touched on this in a September presentation recommending the bivalent vaccines. According to the committee, studies have shown that waiting longer between infection and vaccination may result in a better response to the vaccine.
A COVID infection can also provide your body with a type of “natural” immunity—or immunity acquired from exposure to a disease—that’s similar to the response it mounts when you get a vaccine, said Dr. Piedra.
Both things—a better immune response and protection after an infection—led the CDC to allow people to wait three months after a COVID infection to get a booster dose.
The same is true for people who may have gotten another COVID shot recently—they should wait at least two months before getting an additional shot, according to the CDC.
"You'd really like to wait so that the last dose before your booster has has optimal time for the body to respond to [it]," said Dr. Piedra. "And then you can [get] a booster to do [an even] better job."
The bottom line here: If you're feeling well "and you have not [yet] received a booster or been vaccinated in the last two months, and you know that SARS-CoV-2 activity is increasing," said Dr. Piedra, "this is a good time to get [the] bivalent vaccine."