Dual Influenza Protein Targeting May Cut Airborne Transmission in Half

There is a long-standing tension in influenza vaccine design about whether a vaccine should be optimized to prevent viral replication in the host or to prevent transmission to others. New preclinical research from Penn State suggests this may be a false choice. The study, published in Science Advances, demonstrates a way to stop the influenza virus from leaping from one host to the next while continuing to suppress replication inside the host.^1,2

The findings have important implications for next-generation influenza vaccine development and for how pharmacists counsel patients on the limitations of current formulations.^1,2

Study Design and Key Findings

Researchers paired infected “donor” ferrets with uninfected “contact” ferrets—which have remarkably similar respiratory systems to humans—in shared-air cages. This allowed them to directly measure how immunity to hemagglutinin (HA), neuraminidase (NA), or both proteins influenced viral transmission, tracking viral shedding, transmission rates, and viral evolution.¹

Across every scenario tested, animals with immunity to both proteins were consistently less likely to transmit the virus to nearby, uninfected ferrets, with transmission dropping by half. Investigators described this as an additive effect, meaning immune responses to each of the 2 proteins contributed equally to the overall reduction.¹

When viral levels dipped below a certain point early in infection, the probability of spreading the virus fell below 50%, which is an insight that could help guide future vaccine design efforts aimed at limiting transmission itself, not just severe disease.¹

Critically, no consistent escape variants, such as virus mutations that evolve to evade immune protection, emerged across dozens of animal models, suggesting that targeting both HA and NA does not appear to drive rapid viral adaptation.²

"Our work strengthens the growing consensus among experts that influenza vaccines need to target multiple influenza virus proteins to be maximally effective," Troy Sutton, PhD, associate professor of immunology and infectious disease at Penn State and the study's lead author, said in a news release. “Vaccines of the future may need to do more than trigger strong antibody responses. They may need to blunt spread at the source, and that may mean doubling up on the immune targets the virus relies on most.”²

The Influenza Burden Context

The stakes of improving influenza vaccines remain high. The World Health Organization (WHO) estimates that seasonal influenza viruses infect up to 1 billion individuals worldwide each year, with 3 million to 5 million developing severe disease. As many as 650,000 die from influenza infections annually. High-risk populations, including children, older adults, and the immunocompromised, bear a disproportionate share of that burden.¹

Pharmacist Implications

Pharmacists are uniquely positioned to translate emerging influenza vaccine science into meaningful patient counseling. Research supports the positive impact of expanding pharmacist and pharmacy-based roles in immunization protocols, with proactive pharmacy-centered interventions serving as a promising tool to improve vaccination acceptance rates.³

As next-generation HA plus NA vaccines progress through clinical development, pharmacists should be prepared to explain why future formulations may look different from today's products and why that matters for protection. In the near term, pharmacists can emphasize the continued importance of annual vaccination with currently available products while setting appropriate expectations, such as existing vaccines primarily targeting HA and only offering partial protection against transmission.^1-3

Patients with questions about vaccine composition or evolving research should be directed to authoritative sources, including the CDC and WHO, and encouraged to discuss individual risk factors with their health care team.^1-3

REFERENCES

1. Septer KM, Sim DG, Patel DR, et al. Immunity to hemagglutinin and neuraminidase results in additive reductions in airborne transmission of influenza H1N1 virus in ferrets. Sci Adv. 2026;12(11):eaea8719. doi:10.1126/sciadv.aea8719

2. Targeting two flu proteins sharply reduces airborne spread. News release. Penn State. March 13, 2026. Accessed March 17, 2026. https://www.eurekalert.org/news-releases/1119815

3. Murray E, Bieniek K, Del Aguila M, et al. Impact of pharmacy intervention on influenza vaccination acceptance: a systematic literature review and meta-analysis. Int J Clin Pharm. 2021;43(5):1163-1172. doi:10.1007/s11096-021-01250-1