Florian Krammer
Professor of microbiology at the Icahn School of Medicine at Mount Sinai; a leading influenza virologist focused on H5N1 antibody responses and vaccine development.
Last refreshed: 12 May 2026 · Appears in 1 active topic
Would existing flu antibodies protect people if H5N1 became a pandemic strain?
Timeline for Florian Krammer
Mentioned in: B3.13 replicates better in human nasal tissue
Pandemics and Biosecurity- Who is Florian Krammer?
- Florian Krammer is a Professor of Microbiology at Mount Sinai's Icahn School of Medicine, one of the world's leading influenza vaccine researchers and the scientist behind the Universal flu vaccine concept targeting the haemagglutinin stalk domain.Source: https://icahn.mssm.edu/profiles/florian-krammer
- What is a universal influenza vaccine and how close are we to having one?
- A Universal influenza vaccine would target conserved viral proteins like the haemagglutinin stalk, providing protection across multiple subtypes without annual reformulation; Krammer's stalk-based candidates have reached Phase II trials, but broader clinical validation and regulatory approval remain years away.Source: Krammer et al., Nature Reviews Drug Discovery
- Does prior flu infection protect against H5N1 bird flu?
- Krammer's research shows that antibodies from 2009 pdm09 H1N1 infection or vaccination have partial cross-reactivity to H5N1, likely reducing severe disease risk in a pandemic scenario but not preventing infection outright.Source: Krammer lab publications, Mount Sinai CEIRR
- Why is the haemagglutinin stalk a better vaccine target than the head?
- The haemagglutinin stalk mutates FAR more slowly than the head domain, meaning stalk-directed antibodies remain effective across different viral strains and seasons, whereas current head-targeted seasonal vaccines require reformulation each year as the virus evolves.Source: Krammer, Cell Host and Microbe, universal flu vaccine review
- How worried should we be about H5N1 in dairy cows becoming a pandemic?
- Krammer argues the risk is real but partially mitigated by cross-reactive immunity from prior H1N1 exposure; the key unknowns are whether the virus acquires efficient human-to-human transmission mutations and how quickly a matched vaccine could be produced at scale.Source: Krammer public statements, STAT News, 2024-2025
Background
Florian Krammer is a Professor of Microbiology at the Icahn School of Medicine at Mount Sinai in New York and co-principal investigator of Mount Sinai's Center for Excellence in Influenza Research and Response (CEIRR). He trained at the University of Vienna and has built one of the most productive influenza vaccinology programmes in the world, publishing over 400 peer-reviewed papers on influenza virus biology, antigen design, serology, and vaccine immunogenicity.
Krammer's signature scientific contribution is the development of Universal influenza vaccine concepts targeting the haemagglutinin stalk domain, a conserved region of the virus surface that mutates FAR more slowly than the head domain used in current seasonal vaccines. By eliciting stalk-directed antibodies, a Krammer-type vaccine could theoretically provide broad protection across influenza subtypes rather than requiring annual reformulation. This work has attracted major NIH and BARDA funding and entered Phase II clinical trials.
On H5N1 B3.13, Krammer's public focus has been on cross-reactive immunity from pdm09 H1N1 antibodies as a population buffer against severe disease. He is also a leading expert on influenza serology, and his group's assays are used by WHO and CDC for population-level immunity assessments.
In U#2's coverage of the H5N1 situation, Krammer's contribution is his serology-informed pandemic-risk framing. He has noted that the global population is not immunologically naive to group 1 influenza haemagglutinins because of widespread exposure to pdm09 H1N1 since 2009. The cross-reactive antibody response this generates is not sterilising against H5N1, but serosurvey data suggests it correlates with reduced hospitalisation risk. This implies that a B3.13 pandemic scenario, while serious, may produce lower mortality than pre-2009 H5N1 pandemic projections assumed. Krammer has also advocated for faster H5N1 vaccine candidate stockpiling given the active dairy-herd exposure situation.
