The U.S. health authorities face a crucial decision: whether or not to offer new COVID-19 booster shots this fall that have been modified to better match the coronavirus’s recent changes.
As per The Associated Press, Moderna and Pfizer have tested updated vaccines against the highly contagious omicron variant. On Tuesday, FDA advisors will discuss whether it’s time to make a switch, paving the way for similar actions in other nations.
“This is science at its most challenging,” FDA vaccine chief Dr. Peter Marks told The Associated Press, adding that a final decision is anticipated within a few days of the advisory panel’s recommendation.
In their first year of use, current COVID-19 vaccines saved millions of lives around the world. After a booster dose, the Moderna and Pfizer vaccines continue to provide robust protection against the worst outcomes — severe illness and death.
However, these vaccines target the original coronavirus strain, and due to waning immunity and an unrelenting onslaught of variants, protection against infection has declined significantly. Given that it is impossible to predict which mutant will pose the greatest threat, the difficulty lies in determining if modified boosters have a good chance of thwarting a subsequent surge.
In an analysis prepared for Tuesday’s meeting, FDA officials acknowledged that targeting last winter’s variant of omicron is “somewhat obsolete” because it has been replaced by its even more contagious relatives.
“We would obviously like to get it right,” Marks stated, so that with one more attempt, “we receive a full season of protection.” According to a number of experts, updated boosters offer marginally more benefits.
It is more likely to be beneficial than administering additional doses of the current vaccine, according to Harvard T.H. Chan School of Public Health epidemiologist William Hanage. The assumption is that the virus will not throw another curve ball.
Dr. Eric Topol, director of the Scripps Research Translational Institute, has urged a major government push for next-generation immunizations. “It’s so frustrating that we haven’t developed a better vaccine that is resistant to variants,” he said.
Concerns about a winter COVID-19 outbreak are heightened by the fact that roughly half of Americans eligible for the all-important first booster dose did not receive it. A revised version may attract some of them.
However, “we do need to adjust our expectations,” according to Dr. William Moss of the Johns Hopkins Bloomberg School of Public Health, who noted that early pandemic studies raised unrealistic hopes of preventing even mild infections. To prevent infections, we cannot use booster doses every few months or even every six months.
The leading candidates are what scientists refer to as “bivalent” vaccines, which combine the original vaccine with omicron protection. John Wherry, an immunologist at the University of Pennsylvania, explained that the original vaccines stimulate the production of at least some virus-fighting antibodies potent enough to cross-react with newer mutants, in addition to their proven efficacy against severe disease.
“The ability to slightly adjust the boost response in one direction or another without sacrificing the engine’s core is crucial,” he said.
Moderna and Pfizer discovered that their combination vaccines significantly increased the levels of antibodies against omicron in adults who had already received three vaccinations, as compared to administering another regular dose.
Recipients also developed antibodies capable of combating omicron’s newest relatives, BA.4 and BA.5, albeit not as many. It is unclear how much and for how long this will translate into protection.
Antibodies are an essential first line of defense that develop following vaccination or a previous infection. They can prevent infection by recognizing the spike protein, the outer coating of the coronavirus, and preventing it from entering your cells.
However, antibodies naturally wane, and because each new variant has a spike protein with a different appearance, it has a greater chance of evading detection by remaining antibodies.
Separate studies published this month in Nature and the New England Journal of Medicine demonstrate that the most recent omicron relatives are even more adept at evading antibodies — both in vaccinated individuals and those who have recovered from the original omicron.
The initial immunization was intended to improve immune memory, which helps to explain why protection against hospitalization and death is proving more durable. If the virus is able to evade the immune system’s antibodies, T cells attack the infected cells to prevent disease.
Nevertheless, as people age, every component of their immune system gradually weakens. Little is known about the duration of T cell protection against COVID-19 or how it varies among different mutations or vaccines.
Wherry and dozens of other scientists recently petitioned the FDA to measure T cells in addition to antibodies when determining vaccination strategies.
The Biden administration has made it clear that it requires additional funding from Congress so that, if the FDA approves updated boosters, the government can purchase enough for every interested American.
And Dr. Anthony Fauci, the government’s leading infectious disease expert, told Congress last week that more funding for research is necessary to develop better next-generation vaccines, such as nasal versions that may block infection in the nose more effectively or variant-resistant shots.