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Bivalent Boosters Are Better Against Recent COVID Strains: Pfizer

Nov. 7, 2022 – If you’re among the 92% or so of Americans yet to get a bivalent COVID-19 booster, here’s some news to consider. The Pfizer/BioNTech updated vaccine triggers a stronger immune response than a fourth dose of their original vaccine, the company says.

This evidence supports getting this Omicron-specific booster before a potential COVID-19 surge this winter.

The bivalent vaccine offers the strongest protection in people older than 55. One month after receiving a booster, those in this age group had four times more neutralizing antibodies against Omicron BA.4 and BA.5 subvariants than others who received the original vaccine as a booster.

The researchers compared neutralizing antibody levels before and after the booster in different age groups. They found that levels increased 13 times in the 36 people in the study older than 55 and almost 10 times in the 38 people ages 18 to 55. By contrast, levels increased three times in the group of 40 people who received the original vaccine as a booster.

The bivalent product contains two strains of vaccine – one to protect against the original COVID-19 virus and another to protect against these Omicron subvariants.

The newly released data is “very encouraging and consistent now with three studies all showing a substantial three- to fourfold increased level of neutralizing antibodies versus BA.5 as compared with the original booster,” says Eric Topol, MD, director of the Scripps Research Translational Institute in La Jolla, CA, and editor-in-chief of Medscape, WebMD’s sister site.

Pfizer/BioNTech announced the updated findings in a Nov. 4 news releases.

The bivalent vaccine is authorized for emergency use in people aged 5 and older. CDC data this week show that 8.4% of eligible Americans have received the bivalent vaccine. The agency also estimates about 2,500 Americans are dying from COVID every week.

The safety profile of the Pfizer/BioNTech bivalent booster remains favorable and similar to the original COVID-19 vaccine, the company says.

Until recently, the BA.5 Omicron variant was the dominant strain in the United States but is now getting elbowed out by the subvariants BQ.1.1, BQ.1, and BA.4.6, which together makeup almost 45% of the circulating virus.

Some Skepticism

“It is important to note that these data are press-release level, which does not allow a view of the data totality,” says Hana El Sahly, MD, professor of molecular virology and microbiology at Baylor College of Medicine in Houston, TX.

“For example, there may be significant differences between the groups, and the release mentions at least one difference that is of importance: the interval since the last vaccination, which often affects the response to subsequent boosting,” she says. The findings are not surprising, says El Sahly.

“In the short term, a variant-specific vaccine produces a higher level of antibody against the variant in the vaccine than the vaccines based on the ancestral strains.”

More research results are warranted.

“These data do not indicate that these differences between the two vaccines translate into a meaningful clinical benefit at a population level,” El Sahly says.

An Uncertain Winter Ahead

“As we head into the holiday season, we hope these updated data will encourage people to seek out a COVID-19 bivalent booster as soon as they are eligible in order to maintain high levels of protection against the widely circulating Omicron BA.4 and BA .5,” Albert Bourla, Pfizer chairman and chief executive officer, said in the news release.

The updated data from the Pfizer/BioNTech study are “all the more reason to get a booster, with added protection also versus BQ.1.1, which will soon become dominant in the US,” Topol says.

It is unclear when the next surge will happen, as COVID-19 does not always follow a seasonal pattern — at least not yet, says El Sahly.

“Regardless, it is reasonable to recommend additional vaccine doses to immunocompromised and frail or older persons. More importantly, influenza vaccination and being up to date on pneumococcal vaccines are highly recommended as soon as feasible, given the early and intense flu season.”

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