The study/research recently published in Science Translational Medicine journal shows, a vaccine for H1N2 spurred pigs to produce antibodies that bound the cap and the stem of that virus’s haemagglutinin. But some of those antibodies also targeted the stem of H1N1’s haemagglutinin protein, helping that virus fuse to cell membranes. That made H1N1 more efficient at infecting pigs and causing disease.

This study suggests a role for fusion-enhancing anti-HA2 antibodies in VAERD, in the absence of receptor-blocking virus-neutralizing antibodies.

Reference:

http://www.nature.com/news/flu-vaccine-backfires-in-pigs-1.13621#/b1

http://stm.sciencemag.org/content/5/200/200ra114