Figure 2.

Percentage of heterologous and homologous seroconversion events detected in the FLU09 cohort from 2009 to 2014. Table below indicates the number of influenza-positive participants with paired sera available for testing according to infecting subtypes. Percentages of total Flu +ve are indicated in parentheses. Homologous seroconversion refers to seroconversion event against the infecting influenza subtype (either H1N1, H3N2 or influenza B), as detected by subtyping polymerase-chain-reaction (PCR) method. Heterologous seroconversion refers to seroconversion event to any of the other non-infecting influenza subtypes.