Ongoing transmission of avian influenza A viruses in Hong Kong despite very comprehensive poultry control measures: A prospective seroepidemiology study

There was a significant increase of serum A(H5N1) and A(H9N2) HI titers among Hong Kong LPM workers between 2013 and 2014. Although we cannot exclude some degree of antibody cross-reactivity with other influenza viruses, our results suggest the occurrence of subclinical AIV infections in this population.