Southern Hemisphere Influenza and Vaccine Effectiveness Research and Surveillance

Huang, Qiu Sue; Turner, Nikki; Baker, Michael G; Williamson, Deborah A; Wong, Conroy; Webby, Richard; Widdowson, Marc-Alain

Thirdly, the disease burden of mild influenza not requiring medical consultation (e.g. school/work-related absenteeism) and influenza infection (symptomatic/asymptomatic) will be estimated from the SHIVERS serosurvey. Additionally, we will also conduct severity assessment using true numbers of infections as the denominator to calculate case/fatality and case/hospitalization ratios. Furthermore, the data on influenza disease burden will allow us to estimate direct medical costs and indirect societal costs (e.g. loss of productivity, loss of earning and loss of life) for the study population and subpopulations. 80, 81 Aetiology Preliminary results in 2013 identified an under-recognized burden of non-influenza respiratory viruses, particularly RSV and rhinoviruses, in SARI and ILI cases in NZ as we have never had active population-based study on these viruses previously although substantial burden of RSV and rhinovirus has been described elsewhere. 82, 83 ILI-associated consultations and SARI-associated hospitalizations for RSV and rhinovirus show different socio-demographic patterns (age, ethnicity and SES) from that of influenza. For example, both ILI-and SARI-associated RSV incidences were similarhigh rates for very young (<1 year and 1-4 years) followed by elderly (≥65 years). This presented a very different agespecific incidence profile from that of influenza (indicated above). This result, together with subsequent multiyear surveillance data, may provide insights on differential effects of various respiratory viruses on the age distribution of the host and disease severity.