Pfizer says this season’s COVID shot boosts immune responses fourfold

Positive results come as Americans face confusing access rules that vary by state.

Pfizer and BioNTech report that their updated mRNA COVID-19 vaccine for the 2025–2026 season produced strong immune responses, boosting neutralizing antibody levels by at least fourfold in older people and those with underlying medical conditions.

The positive results come as Americans face a confusing, state-by-state patchwork of access to the shots under the health secretary Robert F. Kennedy Jr., an ardent anti-vaccine activist who has unilaterally restricted access. Prior to the second Trump administration, all Americans ages 6 months and older had access to the vaccines. But under Kennedy, the Food and Drug Administration limited COVID-19 vaccine approvals to people 65 and older, and people under 64 years only if they have an underlying medical condition.

In Pfizer and BioNTech's latest trial, the companies limited enrollment to these groups. The phase 3 trial included 100 people total, 50 people aged 65 or older and 50 people aged 18 to 64 with an underlying condition. Those conditions included asthma, diabetes, heart conditions, HIV, mental health conditions, Parkinson's disease, obesity, or smoking. All participants had gotten last season's COVID shot at least six months prior to the trial and had not gotten any other COVID-19 vaccines or a COVID-19 infection since then.

This year's Pfizer-BioNTech vaccine targets the SARS-CoV-2 strain LP.8.1, a variant in the JN.1 family. In both age groups in the trial, the LP.8.1 vaccines boosted LP.8.1-neutralizing antibody levels by at least fourfold, on average. There were no new safety concerns relative to previous versions of the shot.

While LP.8.1 was the leading variant at the time regulators had to make a call on target strain for this year's shot, the current leading strain is XFG, another JN.1 family member. Pfizer did testing in mice previously to show that an LP.8.1-targeting vaccine would remain effective against XFG (and other emerging variants) and beat out last year's vaccine at providing protection.

While the trial data bodes well for the vaccine's effectiveness this year, it may offer little comfort to Americans struggling to gain access to the shot. According to a public health coalition funded by Kaiser Permanente, people eligible for the vaccine based on the new FDA criteria still need a prescription to get one in 10 states as of September 8. Off-label use (healthy children and adults) remains highly restricted in all states. That said, the situation is still evolving, and some states have already taken various actions (the states with diagonal lines in the map above) to clarify and ease access to COVID-19 vaccines this season.

Source

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Posted Wednesday 10 September 2025 at 12:50 pm AEST (my time).

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