Concurrent epidemics of influenza A/H3N2 and A/H1N1pdm in Southern China: A serial cross-sectional study

The study provides a broad transmission picture and epidemiological characteristics of the major flu subtypes. The findings suggest that it may be necessary to include the A/H1N1pdm strain to the current trivalent or quadrivalent vaccine design. The delayed antibody response cycle in the elderly group indicates the need for better protection of elderly people that might be achieved by an earlier vaccination at a higher dose.