By Josh Nathan-Kazis

Dramatic changes wrought by health secretary Robert F. Kennedy Jr. on vaccine regulation in the U.S. are making this year's launch of the updated Covid-19 shots the rockiest in years, with sharply narrowed approvals leading to roiling uncertainty about who can get the new shots.

Amid all the disruptions and uncertainty, however, Pfizer said Monday that new data show that the updated shot it launched in August works well.

Under Kennedy, a leading vaccine skeptic who has been particularly critical of the messenger RNA-based Covid-19 vaccines manufactured by Pfizer and Moderna, the Food and Drug Administration in August issued a dramatically narrowed approval for the new Covid-19 shots, making them available only to people over age 65 and younger people who are at high risk.

Major questions remain about the accessibility of and insurer coverage for this year's shots. Answers could be forthcoming at an upcoming meeting of a powerful Center for Disease Control and Prevention vaccine advisory committee whose members have been handpicked by Kennedy. Many of those Kennedy appointees are noted opponents of mRNA-based vaccines. The meeting is scheduled to begin Sept. 18.

In the meantime, Pfizer and its partner BioNTech on Monday built the case that their new shot, targeted to protect against a strain of the coronavirus that causes Covid-19, called LP.8.1, offers good protection against the virus.

The companies said that in a trial of 100 adults, half of them aged 65 and up and half of them aged 18 to 64 who were at high risk of severe Covid-19, a dose of the new shot increased blood levels of neutralizing antibodies that target LP.8.1 by "at least" fourfold on average after two weeks.

The trial is ongoing, with additional blood to be drawn and tested later. The company has not previously disclosed data on blood drawn two weeks after injection. Prior immunogenicity data on older Covid-19 shots is generally based on blood drawn a month after injection, when immune responses peak.

The disclosure comes amid political controversy over the efficacy of the Covid-19 shots. Last week, after President Donald Trump posted on his social-media network Truth Social that Pfizer doesn't show its Covid-19 vaccine data "to the public," Pfizer responded with a statement attributed to its CEO, Albert Bourla, that said that the first Trump administration's creation of Operation Warp Speed to combat Covid "would typically be worthy of the Nobel Peace Prize."

Pfizer and BioNTech released the preliminary results just days after that statement. The companies did not offer detailed results from the trial, which is the first available clinical data on the new shots. The FDA approved the vaccine in late August based on pre-clinical data on the updated shots and on data on the older versions of the Pfizer shot.

"Data from evaluable participants showed that the LP.8.1-adapted COVID-19 vaccine elicited a robust immune response against the LP.8.1 sublineage," the companies said. "The safety profile of the vaccine was consistent with previous studies, with no new safety concerns identified. The favorable neutralizing antibody responses and consistent safety profile of the LP.8.1-adapted vaccine for individuals with higher risk and who had been previously exposed to SARS-CoV-2 provide early information for prescribers for this year's vaccination period."

Investors have paid little attention to the shots this year, which were once cash cows for Pfizer, Moderna, and BioNTech but have since seen their sales plummet. Analysts anticipate Pfizer will report sales of its Covid-19 shot of just $4.8 billion this year, down from $37.8 billion at peak in 2022.

Write to Josh Nathan-Kazis at josh.nathan-kazis@barrons.com

This content was created by Barron's, which is operated by Dow Jones & Co. Barron's is published independently from Dow Jones Newswires and The Wall Street Journal.

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September 08, 2025 13:41 ET (17:41 GMT)

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