Deaths from influenza and respiratory syncytial virus
Influenza and respiratory syncytial virus (RSV) infections occur at about the same time each winter and may give rise to similar symptoms. The role of each virus in winter mortality is therefore unclear. A study of national data for England (
) has provided some clarification.
National mortality data were analysed for the winters (early October to early May) of 1989–2000. Neonatal deaths were excluded and deaths were grouped by age (1–12 months, 1–4 years, 5–9 years, and 10–14 years). “Virus active” weeks for influenza were defined from clinical and virological surveillance data and for RSV such weeks were defined by at least 200 reports of RSV infection submitted to the Health Protection Agency. Mortality rates in “virus active” and “virus non-active” weeks were compared.
Influenza was estimated to cause 22 winter respiratory deaths and 78 all-cause deaths each year in children aged 1 month to 14 years. The corresponding figures for RSV were 28 and 79 deaths each winter. Among infants aged 1–12 months average winter mortality from RSV was 8.4 per 100 000 population and from influenza 6.7 per 100 000. The corresponding rates in 1–4 year olds were 0.9 and 0.8 per 100 000, in 5–9 year olds 0.1 and 0.2 per 100 000, and in 10–14 year olds 0.2 and 0.4 per 100 000.
The two viruses cause similar numbers of deaths in children. Compared with RSV, influenza causes fewer deaths in infancy, about the same number of deaths in preschool children, and more deaths in school age children.
