Who actually needs a fourth Covid-19 shot?


Travelers walk past a sign offering free Covid-19 vaccinations and booster shots at a pop-up clinic in the international arrivals area of Los Angeles International Airport on December 22, 2021. Experts say that if you are immunocompromised, you should get a fourth Covid-19 vaccine shot. For everyone else, the jury is still out. | Frederic J. Brown/AFP via Getty Images

Most people don’t need a fourth Covid-19 shot yet. But for some, it’s very important.

Before the omicron wave ripped through the country, infecting even those with multiple doses of the Covid-19 vaccines, evidence was already emerging that the effectiveness of vaccines to protect against infection started to wane after several months. Booster shots were soon approved in response, to recharge people’s immunity against a virus that is still widespread.

By now, for some Americans, it’s been months since those booster shots. Israel, which has taken one of the most aggressive approaches to vaccination, is considering fourth doses for all adults, So that raises the question for boosted Americans: Am I going to need a fourth shot?

For now, experts say, it depends. If you are immunocompromised, yes, you should get a fourth shot — and you’re already eligible. For everyone else, the jury is still out, although a fourth shot doesn’t appear to be immediately on the horizon.

Experts say that because immunocompromised people are more vulnerable right now, it makes sense for them to get another dose of the vaccines currently available. For everybody else, scientists are still assessing whether another dose is actually necessary, as well as what kind of dose it should be.

Immunocompromised people already qualify for four doses under the CDC’s recommendations. Eligible patients include people who are receiving cancer treatment, people who have received an organ transplant, people with HIV infections, and people who have autoimmune disorders or who are taking medications that can suppress their immune system.

Immunocompromised people did not receive the same level of protection from the initial two-dose regiment of the Pfizer and Moderna vaccines, which is why they were one of the first groups made eligible for booster shots last fall. For them, three doses effectively serve as their first vaccine course, with a booster to be given several months after that.

Preliminary studies out of the UK, US, and France have indicated that about half of the immunocompromised people who did not see any immune response after two doses did experience a response after the third dose, and more robust research is underway to assess the effectiveness of a fourth shot, particularly for immunocompromised people.

There have been reports of people who meet those criteria being turned away at pharmacies, another example of poor communication in the US pandemic response. But the Biden White House held a call with pharmacists last week to more clearly lay out who is eligible for an additional shot and ensure those people are not denied the opportunity to bolster their immune system’s response to Covid-19.

So immunocompromised people are the priority for fourth shots right now. For everybody else, experts say we’ll need to wait and see.

One Israeli study found a strong antibody response after four doses of the original vaccine, though it wasn’t sufficient to fully prevent infection from the omicron variant. israel, one of the most aggressive on booster shots, has made all adults over 60 years old, health care workers, and nursing home residents eligible for a fourth shot. It is considering fourth shots for all adults over 18 after at least five months has passed since their third dose or a Covid-19 infection.

For the time being, the half-dozen experts I asked about fourth shots were unanimous that an additional dose makes sense for the immunocompromised, but say the evidence is not yet persuasive for the wider population, at least until some of the studies being conducted on fourth shots and on omicron-specific vaccines are completed.

Pfizer and Moderna are focusing on omicron-specific doses; Pfizer has said that vaccine could be available as soon as March, and Moderna also expects results from its clinical trials next month.

“I’m not persuaded that fourth shots are necessary. We’ll have to see when the actual data comes out,” Angela Rasmussen, a virologist with the Vaccine and Infectious Disease Organization, told me. “With, as you point out, the exception being immunocompromised people.”

The next shot that many people receive may be more targeted to the latest variant. Some scientists even argue we need vaccines that combine the old and the new formulations, in case the next variant after omicron has genetically more in common with earlier strains.

The underlying point is, the original version of the vaccines may be in need of an update. But the data is still coming in on how urgent those additional shots are for most people.

And be aware: The thinking could change in the coming months. Monica Gandhi, an infectious disease researcher at the University of California San Francisco, told me that she thought people over 75 with multiple chronic conditions might benefit from another dose. William Hanage, a Harvard epidemiologist, said that if a fourth shot were shown to prevent any infection, even for a short time, it might make sense to again inoculate medical workers during future surges in order to prevent hospitals from becoming understaffed.

The science is always changing. And we could be moving into a future where periodic Covid-19 boosters are a part of the usual vaccine schedule, like annual flu shots. Moderna’s chief medical officer told CNBC this week that he thought omicron-specific vaccines could fill that role going forward.

As Peter Hotez, who leads the Center for Vaccine Development at Texas Children’s Hospital, told me: “We need clarity on the durability of mRNA vaccines.”

But what should not be lost in this debate is that the vaccines we do have, and the doses already administered, are doing a lot of good. People with three doses had a 96 percent reduced risk of hospitalization from omicron, according to a recent CDC study; even the people with only two doses saw an 81 percent reduced risk. Though immune responses vary by age and health, the vast majority of elderly people still showed an immune response five months after their third shot.

A projection from the Commonwealth Fund estimated the Covid-19 vaccines had saved as many as 1.1 million lives through November 2021. So while the situation is always changing, as omicron reminded us, the basic value of vaccination has not. Some of us might need an additional shot right now. The rest of us might need one later.

But the takeaway remains the same: Get your shots as recommended. They save lives.