In this Brief Report we provide updated results (October 11, 2023 through February 29, 2024) from our previously conducted test-negative case-control study in Kaiser Permanente Southern California to evaluate sub-lineage-specific effectiveness of the BNT162b2 XBB1.5-adapted vaccine. Results suggest that XBB1.5-adapted vaccines may have reduced effectiveness against JN.1 versus XBB sub-lineages.

LJ, LP, and JMM are employees of and hold stock and/or stock options in Pfizer Inc. SYT, TF, JMS, and BA received research support from Pfizer during the conduct of this study that was paid directly to KPSC. BA received research support for work unrelated to this study provided by Pfizer, Moderna, Dynavax, Seqirus, GlaxoSmithKline and Genentech. JMS received research support from ALK, Inc., Dynavax, and Novavax for work unrelated to this study. TBF previously owned stock in Pfizer Inc. SYT received research support from Genentech for work unrelated to this study.

This study was sponsored by Pfizer. The study design was developed by KPSC but approved by Pfizer. KPSC collected and analyzed the data. Pfizer did not participate in the collection or analysis of data. KPSC and Pfizer participated in the interpretation of data, in the writing of the report, and in the decision to submit the paper for publication.

I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.

Yes

The details of the IRB/oversight body that provided approval or exemption for the research described are given below:

The Institutional Review Board of Kaiser Permanente Southern California gave ethical approval for this work and waived the requirement for informed consent.

I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals.

Yes

I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance).

Yes

I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable.

Yes

Anonymized data that support the findings of this study may be made available from the investigative team in the following conditions: (1) agreement to collaborate with the study team on all publications, (2) provision of external funding for administrative and investigator time necessary for this collaboration, (3) demonstration that the external investigative team is qualified and has documented evidence of training for human subjects protections, and (4) agreement to abide by the terms outlined in data use agreements between institutions.