Pharmaceuticals Urge for Fourth COVID-19 Booster Shot

Concerns of an incoming wave of Omicron subvariant BA.2 led pharmaceuticals Pfizer and Moderna to request an FDA authorization for a fourth COVID-19 shot, or a second booster shot. However, the scientific community said that it is too early to know if the extra shot is needed.

BA.2 is a subvariant of Omicron BA.1, the original variant, which was first identified in Jan. 2022.  BA.2 differs from other Omicron subvariants in its genetic sequence and lacks a mutation that allows PCR tests to identify the type of variant (Omicron or Delta) affecting the patient. This was particularly important during the Omicron wave because monoclonal antibodies were found to be less effective to treat Omicron than Delta.

"It was useful then to know if the person in front of me had Delta and I could use monoclonal antibodies or if they had Omicron and I should not," Cameron Wolfe, Associate Professor of Medicine, Duke University School of Medicine Wolfe, told NBC News.

Preliminary studies suggest that BA.2 could be more contagious than the original Omicron, but there are no indicators suggesting that it has severely changed hospitalizations or deaths. The primary concern is that BA.2 could start yet another COVID-19 wave in the Americas, as it has been spreading in the EU and Asia. Furthermore, “early reports show that vaccines are roughly as effective against BA.2 as they are against the original strain of Omicron,” according to NBC News.

Pfizer asked the FDA to approve a second booster for adults over 65 years old that have already received one booster shot. Pfizer’s request seems to be moving faster than Moderna’s, which is asking the FDA to authorize its vaccine for a second booster for all adults. Moderna said, according to the Boston Globe, it wanted to give the US Centers for Disease Control and Prevention (CDC) and health care providers flexibility in deciding who should get boosters and when they should get them.

In its justification for seeking second boosters for people 65 and up, Pfizer relied heavily on evidence from two studies conducted in Israel that suggested that people who had received fourth shots were less likely to become infected with the virus, compared with those who had received three doses.

Concerns over booster doses are both biological and socioeconomic. Omicron changed the thinking around boosters, says Alejandro Balazs, an immunologist at the Ragon Institute in Cambridge, Massachusetts. This is because, faced with the variant, people previously regarded as fully vaccinated now have “an antibody response that is insufficient to prevent infections,” Nature explained.

Preliminary results have shown that a third shot might already provide long-lasting immunity in most cases and an observation study on Israel found that a fourth shot against COVID-19 provided only slightly higher levels of protection against infection and severe disease with Omicron.

The WHO has said that providing endless shots against COVID-19 is an unsustainable approach. By the end of 2021, wealthy countries have rolled out more COVID-19 boosters than the total number of all doses administered so far in poorer nations, said the Financial Times. This trend is likely to continue as countries prioritize their own populations over those abroad, according to The Lancet.

In Mexico, booster shots have been administered throughout 2022. By early March, Mexico had administered over 6 million boosters, while in the US 96.5 million people received a booster shot.