Near real-time data on the human neutralizing antibody landscape to influenza virus as of early 2026 to inform vaccine-strain selection

We just posted to bioRxiv a new study that measures the current human neutralizing antibody landscape to human seasonal influenza. These data help explain the recent spread of new subclades of H3N2 and H1N1 influenza, and can help inform the upcoming decision on which strains to choose for the 2026-2027 Northern Hemisphere influenza vaccine.

A goal of our lab is to develop new methods that can characterize the forces shaping viral evolution on a timescale that is helpful for countermeasures like vaccines. Over the last few years, our lab has developed sequencing-baed neutralization assays and computational pipelines to analyze the data. We've now been working to leverage these tools to generate near real-time data on human neutralizing antibody immunity to influenza to inform the twice-per-year vaccine update decisions.

About six months ago we posted a study led by graduate student Caroline Kikawa that provided real-time data on the human neutralizing antibody landscape as of the late summer of 2025; these data were considered at the September 2025 vaccine-composition meeting for the 2026 Suthern Hemisphere vaccine. Now we've posted a new preprint with data on the current landscape that can be used for the upcoming decision about what vaccine to use for the 2026-2027 Northern Hemisphere influenza season.

There are lots of interesting scientific findings in the study, including explanations of why subclade K of H3N2 (which is primarily responsible for the bad influenza season this year) and subclade D.3.1.1 of H1N1 have become dominant. Our results also hint at what might be next in H3N2 evolution.

In addition to reading the preprint, for more details see:

• This Bluesky thread, which can be read more easily in threaded form here.
• This X thread

I'd also note that we've been posting the data on GitHub in real time as it was collected; Caroline recently won a Beyond The Journal award for this exemplary data sharing.

To access and view the data, see the following links:

• Computer code and numerical data: https://github.com/jbloomlab/flu-seqneut-2025to2026
• Interactive visualizations of measurements: https://jbloomlab.github.io/flu-seqneut-2025to2026/
• Interactive phylogenetic trees with H3N2 titers: https://nextstrain.org/community/jbloomlab/flu-seqneut-2025to2026@main/H3N2
• Interactive phylogenetic trees with H1N1 titers: https://nextstrain.org/community/jbloomlab/flu-seqneut-2025to2026@main/H1N1