Health officials in Canada and Britain have already said they will allow elderly, immunocompromised and other high-risk people to receive an additional bivalent coronavirus booster shot six months after their previous one. U.S. officials should follow suit and give the choice to vulnerable individuals who want to “top-up” their protection.
For months, the single-most common question I have received from readers has been when they can get a second bivalent dose, which targets the omicron strain and its subvariants. Those asking have predominantly been in their 70s or older — with many having multiple underlying medical conditions. They worry that because their last dose was in September, when the bivalent booster first became available, they are no longer as protected against the coronavirus.
They are right to be concerned. Immunity from the last vaccine dose has probably substantially decreased, and there’s plenty of reason to believe that a second bivalent shot can restore protection.
The Food and Drug Administration and the Centers for Disease Control and Prevention have not yet issued recommendations on second bivalent boosters, citing lack of evidence. Instead, they are discussing an annual fall vaccine campaign — a plan I support because of its ease of implementation. But broad guidance for the public to receive a yearly vaccine shouldn’t prevent high-risk people from accessing more frequent shots.
Abundant research demonstrates that vaccine effectiveness wanes quickly against the dominant omicron subvariants. A CDC study last year found that while the original monovalent booster was 89 percent effective at preventing hospitalization against omicron, this protection dropped to 66 percent after four to five months. Protection against emergency department or urgent care visits dropped further, from 83 percent to 46 percent. The waning effect was particularly pronounced among immunocompromised patients.
Researchers in Qatar reached a similar conclusion. Among patients deemed vulnerable to severe covid-19, protection against infection declined from 61 percent in the first month after the booster to only about 16 percent by the sixth month. Another study found that protection waned more rapidly in older people.
These studies were done with the monovalent shot, not the updated bivalent one. While the bivalent booster appears to have the edge over the original vaccine against circulating strains, the bivalent vaccine probably wanes quickly, too. In fact, the CDC’s own data show effectiveness against infection has substantially decreased by four to five months.
A second bivalent booster would almost certainly restore some protection. The benefit might be negligible for healthy young people who are already well protected from severe illness, especially if they have hybrid immunity from vaccination and prior infection. But that is not the case for three groups for whom this added protection could make a difference.
The first includes people who are moderately or severely immunocompromised. Before bivalent vaccines, this group of approximately 7 million Americans was advised to receive one more monovalent shot than everyone else. They should be able to receive additional bivalent shots, too, in consultation with their physicians.
The second group includes medically frail people who are older and already in poor health from conditions such as chronic kidney disease and congestive heart failure. These individuals represent the vast majority of people dying from covid. They should try to avoid any respiratory infection; a virus that’s mild for others could land them in the hospital or worse. This is especially important if they are ineligible for Paxlovid, the antiviral pill that reduces progression to severe disease.
Finally, there are the “worried well.” These people might be higher risk in some ways — for example, they are older but do not have severe underlying conditions — and they highly prioritize avoiding covid. To them, an extra vaccine dose is like choosing to mask in certain high-risk settings or testing before gathering. Because booster shots are hardly in short supply, there is no good reason to withhold the vaccine from this group, either.
Allowing an additional vaccine dose doesn’t have to muddy the messaging about annual boosters. The FDA and CDC could say that the public should wait to get their booster in the fall, but that the additional spring booster is an option for those who want it now. Of course, the public health focus should be getting vulnerable people to receive their first bivalent boosters. But that shouldn’t get in the way of others eager to get their second — and who will likely be first in line to receive another shot in the fall.
In fact, I think this permissive, choose-your-own approach to boosters mirrors the approach to covid taken by the Biden administration — and most of the United States. For months, people have been gauging their own level of risk tolerance and deciding which precautions they wish to continue. The extra booster can be considered in this way; most won’t give it a second thought, but for some, it would give more peace of mind as they resume their lives.