
A study published earlier this week in Nature Communications using claims data from the US Veterans Affairs (VA) Healthcare System finds protection from the 2024-25 Pfizer COVID-19 vaccine was 68%, 57%, and 56% against COVID-19–associated hospitalizations, emergency department and urgent care (ED/UC) visits, and outpatient visits, respectively.
However, the authors caution that uptake of the vaccine was extremely low—only 3.7% through November 2024—and the study did not assess waning effectiveness.
The study estimated early BNT162b2 KP.2 (2024-25 formulation) vaccine effectiveness (VE) against COVID-19 outcomes compared to not receiving the vaccine.
In total, 44,598 acute respiratory illness (ARI) encounters with valid SARS-CoV-2 test results were included in the final analysis. Overall, 16.2% (7,224) tested positive for SARS-CoV-2, and 1,666 (3.7%) received the BNT162b2 KP.2 vaccine; 138 of 7,224 COVID-19 patients (1.9%) and 1,528 of 37,374 controls (4.1%) received the vaccine.
Overall VE was 56% against all outcomes
Adjusted VE of the BNT162b2 KP.2 vaccine (compared to not receiving a KP.2 strain-adapted vaccine of any kind) against all COVID-19 outcomes was 56% (95% confidence interval [CI], 48% to 63%).
Additional efforts to improve COVID-19 vaccine uptake to match that of annual influenza vaccine coverage are needed.
Among patients who previously received one or more doses of the XBB vaccine, the adjusted VE of the KP.2 vaccine compared to not receiving the KP.2 vaccine was 77% (95% CI, 50% to 89%), 60% (95% CI, 48% to 69%), and 62% (95% CI, 43% to 75%) against hospitalizations, ED/UC visits, and outpatient visits, respectively.
"Despite this persistent burden and the increased protection observed with receiving updated vaccines over the last two respiratory virus seasons, uptake of updated COVID-19 vaccines remains low, even among older adults," the study authors wrote. "Additional efforts to improve COVID-19 vaccine uptake to match that of annual influenza vaccine coverage are needed."