The Food and Drug Administration (FDA) is weighing the benefits of a second booster shot for vaccinated and boosted Americans. The vaccines combined with an additional mRNA booster shot have reduced rates of hospitalization and incidence of severe disease even while Omicron has increased infection rates. Countries like Sweden, Israel and Chile are already offering a fourth dose to at-risk groups. Would seniors and caregivers in San Diego benefit from a second booster shot?
The FDA is currently studying the benefits of a second booster shot (or fourth dose) of the coronavirus vaccine based on data from other countries who have administered a fourth dose in an effort to combat Omicron. According to the Centers for Disease Control (CDC), the protection offered by the first booster shot drops significantly by the fourth month, so an additional shot of the same vaccine might not be helpful. Health officials are asking themselves several questions:
- Should a second booster shot be authorized for all adults or just particular groups based on age and risk?
- Should this fourth dose target the Omicron variant or have a different formula?
- Will this potential fourth shot begin an annual COVID-19 vaccination program or
- Will another variant come along before flu shot season that requires a booster?
Those most likely to be advised to get a fourth dose of the currently used vaccine will be people at high risk like seniors over age 65, the elderly in home care, people with certain conditions and the immunocompromised. If the corresponding increase in antibodies will help those groups avoid severe disease even for a few months, that’s worth the effort. There is no consensus on when a fourth shot would be appropriate because doctors are still studying the immunity and protection offered by the third dose. Doctors have not yet determined whether a second booster would also be suggested for a home care companion for seniors, for example, who work around at-risk people.
While health experts are debating a second booster, the evidence is clear that the first booster is necessary and effective against Omicron. The New York Times reports that, “The Omicron variant can dodge antibodies — immune molecules that prevent the virus from infecting cells — produced after two doses of a Covid vaccine. But a third shot of the mRNA vaccines made by Pfizer-BioNTech or by Moderna prompts the body to make a much wider variety of antibodies, which would be difficult for any variant of the virus to evade.” The CDC shared that “[A] third dose [of a mRNA vaccine] was 87% effective against emergency room and urgent care visits and 91% effective against hospitalizations during the 2 months after vaccination. But by the fourth month after a third dose, vaccine effectiveness dropped to 66% against visits to emergency rooms and urgent care centers and 78% against hospitalizations. Without a third shot, protection against hospitalization within 2 months of a second shot was 71%, which fell to 54% after 5 months. Protection declined significantly as the Omicron variant became dominant in the U.S.”
Scientists around the world are still collecting the data that measures the benefits of a second booster shot. In Israel, a group of hospital workers were given a fourth shot, and NPR reports that the study found that “[a]lthough the extra (fourth) shot boosted antibody levels to about the level observed right after the third shot, the rise in antibodies didn’t translate into strong protection against infection. The extra dose reduced the risk of an infection by only about 10% to 30%, Dr. Regev-Yochay [the infectious disease specialist who conducted the study] and her team report. During the 30-day study period, about 20% of the people who received the extra shot became infected with the omicron variant of the coronavirus, compared with about 25% of the people who received only three shots.” The conclusion is that a fourth dose brings protection levels close to the point reached right after the first booster but doesn’t increase them beyond that.
So, if a second booster shot isn’t the answer, what comes next? Doctors believe that repeated boosters of the original vaccine developed in 2020 simply won’t be infinitely effective against Omicron or future variants. Jenna Guthmiller, an immunologist at the University of Chicago told NPR “I think what’s happening is we’re just reaching a threshold with this vaccine….Omicron, in my opinion, has changed everything. This virus is way more likely to cause an infection, and so what worked for previous variants, such as alpha and even delta, is perhaps not the same vaccine that’s going to be necessary for omicron.” Moderna is working on an Omicron-specific booster. Pfizer is “testing a vaccine that targets the Omicron variant and has said that people may need an annual shot, with high-risk people such as the immunocompromised and older adults potentially needing another dose sooner.” Globally, vaccine makers are preparing for a Covid booster to become an annual event like the flu shot.