Last week, the U.S. Food and Drug Administration advised manufacturers to reformulate booster shots to specifically protect against the BA.4 and BA.5 Omicron variants.
"We have advised manufacturers seeking to update their COVID-19 vaccines that they should develop modified vaccines that add an Omicron BA.4/5 spike protein component to the current vaccine composition to create a two component (bivalent) booster vaccine, so that the modified vaccines can potentially be used starting in early to mid-fall 2022," Peter Marks, director of the FDA's Center for Biologics Evaluation and Research, said in a statement. "Currently available vaccines have helped reduce the most serious outcomes (hospitalization and death) caused by COVID-19, but results from post-authorization observational studies have shown that effectiveness of primary vaccination wanes over time against certain variants, including Omicron."
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The subvariants of Omicron — BA. 4 and BA. 5 — have become the dominant strains in the country, driving a majority of new coronavirus cases in less than six months since they were first discovered in South Africa.
Collectively, the subvariants of Omicron — BA. 4 and BA. 5 — have become the dominant strains in the country, driving a majority of new coronavirus cases in less than six months since they were first discovered in South Africa. As mentioned in the statement, the subvariants evade antibodies produced by coronavirus vaccinations and previous infections. Hence, the driver behind their unprecedented spread.
While vaccine manufacturers are gearing up to pivot due to the recommendation of the FDA to focus on targeting these two highly contagious strains of the coronavirus for a fall booster campaign, some public health experts are wondering if it will be too little, too late — or perhaps a waste of the manufacturers' resources, considering how fast Omicron has mutated. Then, there's the question of whether people will get boosted or not. Currently, about half of vaccinated Americans have received a single booster. Only a quarter of boosted people over the age of 50 who are eligible have received a second one. These boosters would likely be for people who are already fully vaccinated.
"I think it's an unsurprising decision that they made, but I don't know that we have enough data on how to evaluate the decision, and I think it comes back to the point that there's still a lack of clarity on the goals of a booster vaccination campaign— is it to prevent severe disease or prevent infection?" Dr. Amesh Adalja, a senior scholar at the Johns Hopkins Center, told Salon. "If the goal is preventing infection then there's probably a better case for updating the boosters but again, we don't have strong data yet."
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Earlier this month, Moderna said its bivalent booster led to an eightfold increase in neutralizing antibody levels. The company announced its results from a Phase 2/3 clinical trial of 437 people in a news release. In the statement, Moderna's CEO said that the data meant this vaccine is their "lead candidate for a Fall 2022 booster." But as Adalja noted, more data is needed.
L.J Tan, chief strategy officer for the Immunization Action Coalition, told Salon he thinks the FDA's advisory is a logical next step at this point in the pandemic.
"I think we have to continue to evolve our vaccine, right? So from the very highest level, it's a good idea; we don't want our vaccine technology to stagnate," Tan said. "But it doesn't mean that when they actually bring the product to the FDA for either authorization or licensure that it will get either, but I think it's a necessary first step."
Tan cautioned that people might "read too much" into this news though. For example, it might lead people to jump to conclusions that the current vaccines that target the original coronavirus strain are no longer effective.
"Definitely not [the case]," Tan said. "This simply means that they are wanting the manufacturers to bring to them for consideration — either for authorization or licensure — another [booster] vaccine for consideration."
While studies have shown that BA.4 and BA.5 evade antibody responses from the vaccines or previous infections, they are holding up in protecting against severe disease and hospitalization.
Indeed, while studies have shown that BA.4 and BA.5 evade antibody responses from the vaccines or previous infections, they are holding up in protecting against severe disease and hospitalization.
While there are concerns about whether a booster targeting these subvariants will be needed in the fall — say, there's a more transmissible that's spreading around by then — Adalja told Salon that will always be the case when it comes to manufacturing booster shots.
"There's always going to be a lead time to manufacturing," Adalja said. "There is a chance that by the time these vaccines are available, that vaccines targeting BA.4 and BA. 5 won't be very useful, so again, I think that there's a much better case to be made for investing in better vaccines, rather than following this same kind of pattern."
In this hypothetical situation, the country could end up with "suboptimal vaccines," Adalja said, with companies who are facing sunk costs and time wasted. "Instead of spending the money and efforts on trying to come up with booster policies, why not put more into developing a universal coronavirus vaccine?" Adalja said, adding that this game of catch-up could be distracting manufacturers "from making better vaccines."
However, Tan told Salon, he thinks it's "unlikely" that in the fall there will be another variant that's so dramatically different, the potential new boosters wouldn't make some sort of an impact by fall.
"I don't think that it's going to drift so much that a vaccine that contains either of those existing Omicron epitopes is going to not work," Tan said. "So for that reason, I don't think that we're going to get this horrible strain that's going to evade everybody's vaccine response, and that's just because of the way the virus evolves."
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