Should you get a Covid-19 booster now, or wait until the fall?

As the Omicron subvariants BA.4 and BA.5 continue to make viral waves, pharmaceutical companies are revamping their booster shots. Last week, Pfizer and its German-based partner BioNTech applied to the U.S. Food and Drug Administration for emergency use authorization for its booster jab targeting the original SARS-CoV-2 strain (which emerged at the pandemic’s outset) and the Omicron sublineages. Moderna has also tossed its reformulated jab into the approval ring.

If the FDA gives its thumb’s up, both vaccines could become available in September. This effort will hopefully provide renewed protection against a fall Covid-19 surge forecasted to infect as many as 100 million Americans, the Biden administration warned back in May.

By now, over 67 percent of the U.S. population is fully vaccinated, 48 percent have received at least one booster, and 33 percent over age 50 have gotten a second booster shot, according to the latest data from the Centers for Disease Control and Prevention. While having so many people vaccinated is great, SARS-CoV-2 — the virus behind Covid-19 — unfortunately, is quite the shape-shifter, mutating in ways to avoid the immunological defenses built up by vaccines.

Inverse spoke with two vaccine experts to get the 411 on boosters — why we need them, who needs them, and when you should get jabbed.

Why do we need boosters?

The job of a vaccine is to teach our immune system how to defend itself quickly against a pathogen, in this case, SARS-CoV-2. But with time, the immunological memory wanes and needs a refresher, which comes in the form of a booster.

The current COVID-19 vaccines on the market teach our bodies to identify the SARS-CoV-2 spike protein that’s found dotting the surface of the virus. The current Pfizer-BioNTech and Moderna boosters target this same protein, whereas the upcoming jabs include mutated variations of it.

“We saw early on when we first made the vaccines, they’re very good matches for circulating strains. They protect really well against any illness, including severe disease,” Kawsar Talaat, an associate professor of epidemiology at the Johns Hopkins Bloomberg School of Public Health, tells Inverse.

“[But] what we’ve realized is that, over time as the Covid-19 virus evolves, the match between the virus and vaccine strains has gotten less strong…The bivalent boosters and the [BA.4 and BA.5 shots] allow us to give a vaccine [containing a strain] that’s very similar to the circulating strain and hopefully will allow for more protection.”

How much protection will you get?

Overall, the vaccines are really good at preventing severe disease, hospitalization, and death, Talaat and Paul Offit, director of the Vaccine Education Center at Children’s Hospital of Philadelphia and an FDA vaccine adviser, both say. But individual immunity is a bit of a “your mileage may vary” situation.

Your particular immune response to SARS-CoV-2 depends on a host of factors such as vaccine history, age, whether you’ve gotten Covid-19 before, and any pre-existing conditions like asthma, diabetes, obesity, or being immunocompromised. (This is also the same for your risk of contracting Covid-19.)

“The goal of the vaccines is to prevent serious illness,” Offit tells Inverse. “You are not going to prevent mild illness.”

But Talaat says the boosters aren’t entirely a bust on that front. In preventing “symptomatic disease, [you’re] also decreasing infections and [thus] decreasing transmission.”

Do you need a booster?

For the most part, yes, especially depending on your health status, says Offit. If you’re over the age of 75, immunocompromised (or taking drugs that could affect or immune system), or have serious comorbidities like severe heart or lung disease, you should definitely get a booster. For healthier individuals, Offit says, who have the advantage of the immunological memory from their previous Covid-19 shots, they arguably could get by without a booster. But according to Talaat, even if you’re strongman Hercules himself (or Xena, the Warrior Princess), you should consider getting the current or new Omicron-specific boosters once those come out.

The same holds true if you’ve had Covid-19 before.

“I think a lot of people will say, ‘Well, I’ve already had Covid, I’ve already been vaccinated, why would we need to get another dose?’” says Talaat. “What we found is that people who have hybrid immunity — so immunity from both the vaccine and infection — are more resistant to reinfection and are protected better than people who had infection alone or even vaccine alone.”

Should you get the current booster now or wait for the Omicron-specific one?

Should you wait for the bivalent vaccines? The problem is a vaccine’s approval process can be very time-consuming. First, an FDA independent committee has to review the data, then get approval from the FDA director, followed by a review from a CDC advisory panel before the CDC itself makes its recommendation. Final approval is made by the CDC director Rochelle Walensky.

While all this is expected to come together in September, it’s not a guarantee. Both Offit and Talaat recommend that individuals eligible for a second booster — adults over 50 and those moderately or severely immunocompromised over the age of 12 — should get it as soon as they can.

“If you’re [among those most vulnerable], I certainly wouldn’t wait for the bivalent vaccine,” says Offit.

If you’ve been vaccinated before and are just shaking off a Covid infection, you need to wait at least three months after you’ve recovered before getting a booster, as per CDC guidelines, says Talaat.

And if you’re somehow able to jump the eligibility gun, the same still holds: You should still strongly consider getting the current boosters available. This in no way precludes you from getting the Omicron-specific boosters once approved. When you could expect that would be contingent upon when you got your last booster, which can range between two to five months depending on your individual risk and prior vaccine received.

Should you mix-and-match boosters?

Thinking of shifting from Team Moderna or Pfizer once the boosters are out? There’s not a lot of evidence suggesting the switcheroo could be advantageous.

“Mix and match studies didn’t really show a big difference in Moderna followed by Pfizer or Pfizer followed by Moderna,” says Talaat. “There may be some benefit to it in terms of protection against infection [and] disease. I don’t know if we have any of that data to show that mix and match is better.”

And remember to get your flu shot!

While the flu vaccine won’t provide you any secondary protection against Covid-19, says Talaat, it’s better to be up to date on all your seasonal shots just to be on the safe side.

Think about it: If it sucks to get Covid-19, it sucks even more to get Covid-19 and the flu.