Study Reveals Greater H5N1 Vaccine Benefits for Younger Adults and Children
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Synopsis
A recent study indicates that younger adults and children stand to gain significantly from H5N1 vaccines, even those not specifically designed for the current strains affecting birds and cattle. The research highlights the role of prior influenza exposures in boosting immunity against H5N1.
Key Takeaways
- Younger adults and children benefit more from H5N1 vaccines.
- Prior exposure to seasonal flu enhances immunity.
- Older adults exposed before 1968 have higher antibody levels.
- Cross-reactive antibodies may limit disease severity.
- H5N1 could mutate for human transmission.
New Delhi, March 15 (NationPress) Research indicates that younger adults and children are likely to experience greater benefits from H5N1 vaccines, even those not specifically designed for the current strains affecting birds and cattle. A study conducted by researchers at the University of Pennsylvania in the US revealed that prior exposure to certain seasonal influenza viruses can enhance cross-reactive immunity against the H5N1 avian influenza virus.
The findings, published in the journal Nature Medicine, show that older adults who had been exposed to seasonal flu viruses prior to 1968 exhibited a greater likelihood of having antibodies that bind to the H5N1 avian flu virus.
According to Scott Hensley, a Professor of Microbiology at the University, “We understand that early childhood exposure to influenza can trigger immune responses that last a lifetime.” He added, “Our research found that antibody responses activated by H1N1 and H3N2 viruses from decades ago can cross-react with today’s circulating H5N1 avian viruses. Although most of these cross-reactive antibodies do not prevent infections, they may help mitigate disease severity in the event of an H5N1 pandemic.”
H5N1 viruses have been present in bird populations for many years; however, a new variant known as clade 2.3.4.4b H5N1 has recently emerged and spread among cattle. This current strain doesn’t bind effectively to receptors in the human upper respiratory tract, yet extensive circulation in mammals might result in mutations that enable the virus to infect human airway cells and enhance transmission.
If such mutations occur, H5N1 could potentially transition to human-to-human transmission. Current influenza vaccines mainly induce antibodies that recognize hemagglutinin proteins, which prevent the virus from infecting human cells.
The research team evaluated blood samples from over 150 individuals born between 1927 and 2016 to identify antibodies targeting stalk proteins of various influenza viruses, including H5N1. They discovered that older adults born before 1968, likely first exposed to H1N1 or H2N2 during childhood, had elevated levels of antibodies capable of binding to the stalk of the H5N1 virus.
Moreover, the study found a significant correlation between an individual’s birth year and the quantity of H5N1-neutralizing antibodies in their blood, indicating that young children who had not encountered seasonal flu viruses exhibited low levels of antibodies against H5N1.
Hensley emphasized that in the event of an H5N1 pandemic, all age groups would likely be highly susceptible, with children potentially facing the highest disease burden. “In such a scenario, prioritizing H5N1 vaccinations for children is essential,” the expert concluded.
