Analysis of the database also found that among six viral surface epitopes that can bind antibody, thereby preventing infection, only one is conserved between 2009 and seasonal H1N1 viral strains.

These results suggest that healthy individuals may have immune memory that recognizes the 2009 H1N1 strain and therefore can mount some measure of an immune attack. The findings also may help explain why the 2009 H1N1 influenza pandemic affects young children more severely than it does healthy older adults and also why two H1N1 vaccinations are needed to protect children ages nine years and under.

ARTICLE: J Greenbaum et al. Pre-existing immunity against swine-origin H1N1 influenza viruses in the general human populace. Proceedings of National Academy of Sciences. DOI: 10.1073/PNAS.0911580106 (2009).

WHO: Allison Deckhut-Augustine, Ph.D., Chief, Immunoregulation Section, Basic Immunology Branch, NIAID Division of Allergy, Immunology and Transplantation, is available for comment.

Source: NIH/National Institute of Allergy and Infectious Diseases