This fall, the FDA approved the rollout of two updated Omicron-specific COVID-19 boosters. These new COVID boosters aim to provide more protection against the two most contagious subvariants of Omicron, BA.4 and BA.5. The new boosters, approved first in the United Kingdom and then in the United States, are now available in both countries. But do the new COVID boosters offer better protection than the old boosters did? Here’s what we know so far.
Unlike the original monovalent COVID-19 boosters, the new COVID-19 boosters are bivalent, containing both the original SARS-CoV-2 strain and the BA.4 and BA.5 Omicron subvariant strains. Because of this, the new COVID boosters have been touted by vaccine developers as being significantly more effective than the old boosters. But is that true? Deborah Cromer, a mathematical modeler, led a research team at the University of New South Wales to find out.
The study revealed that the new COVID boosters’ effectiveness appeared to be comparable to – or only marginally better than – the effectiveness of the old COVID boosters.
COVID Vaccines and Antibody Levels
One area the study focused on was antibody levels in response to the vaccine. One way to measure a vaccine’s effectiveness is to measure the levels of antibodies the body produces in response to it. The more neutralizing antibodies spike in response to a vaccine, the better. Studies have suggested that higher antibody response levels may be equated with better protection against COVID-19 infections and complications.
Cromer’s study did find that the new bivalent booster provoked an antibody response that was, on average, about 1.5x stronger than the antibody response triggered by the older monovalent booster. But, the study notes, this is not a statistically remarkable difference.
Cromer’s team also examined what degree of benefit the antibody data actually conveyed with regard to COVID vaccines in particular. They discovered that most of the benefits from updated COVID-19 vaccines are conveyed by an extra dose of any vaccine.
In other words, there is a clear benefit to receiving a COVID booster, but the new COVID boosters are not significantly better than the old boosters.
Nevertheless, even those small improvements may be enough to justify the rollout of the new boosters. As Cromer’s team notes, small improvements matter at a population level. The team estimated that an updated booster campaign using the new bivalent vaccine would likely result in eight fewer hospitalizations per 1,000 people than a vaccine campaign using the old vaccine booster would. And at a population level, that’s the equivalent of hundreds of thousands – if not hundreds of millions – fewer hospitalizations.
As Cromer puts it, “If that translates to hospital beds saved and severe cases averted, that might be a sufficient level to warrant the recommendation for a variant-modified booster.”
In addition, the researchers stressed that the relative benefits of the new COVID boosters may not yet be fully known. The new COVID booster’s relative effectiveness may also become more evident if pre-existing immunity is abruptly lowered due to the emergence of a new COVID variant (which is what happened in December 2021 with the emergence of Omicron). If this were to happen again, the new bivalent Omicron vaccines may actually be able to provide much stronger protection than older vaccines would have.
Should You Still Get the New COVID Boosters?
As Dean Follmann, a statistician at the U.S. National Institute of Allergy and Infectious Diseases explains, the main takeaway message should be that “any COVID-19 booster is a good one.” Vaccines and boosters continue to be the best way to drive down the number of serious illnesses, hospitalizations, and deaths caused by COVID-19.
So, while researchers may disagree on whether or not the expedited rollout of the new COVID boosters was necessary, they do agree on one point: Get boosted, and get boosted soon.
“Don’t wait,” Dr. Ashish Jha, head of the White House’s pandemic response team, emphasized in an October press briefing, when asked about the new COVID boosters. “Get your new flu shot and get your new COVID shot today. If Americans did that, we could save hundreds of lives each day this winter.”
The new COVID boosters are available at pharmacies, community health centers, and other vaccine sites across the country.
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