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The effect of influenza on mortality is much greater in Japan than in the United States and can be measured about equally well in terms of deaths from all causes and deaths attributed to pneumonia or influenza. Vaccinating schoolchildren against influenza provides protection and reduces mortality from influenza among older persons.

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Our study suggests that respiratory virus infections commonly trigger serious acute respiratory conditions that result in hospitalization of patients with chronic underlying conditions, highlighting the need for development of effective vaccines for these viruses, especially for parainfluenza and RSV.

We reviewed the epidemiology, clinical characteristics, disease severity, and economic burden of influenza B as reported in the peer-reviewed published literature. We used MEDLINE to perform a systematic literature review of peer-reviewed, English-language literature published between 1995 and 2010. Widely variable frequency data were reported. Clinical presentation of influenza B was similar to that of influenza A, although we observed conflicting reports. Influenza B-specific data on hospitalization rates, length of stay, and economic outcomes were limited but demonstrated that the burden of influenza B can be significant. The medical literature demonstrates that influenza B can pose a significant burden to the global population. The comprehensiveness and quality of reporting on influenza B, however, could be substantially improved. Few articles described complications. Additional data regarding the incidence, clinical burden, and economic impact of influenza B would augment our understanding of the disease and assist in vaccine development.

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We examined the relation of invasive pneumococcal disease to season, atmospheric conditions, and the rate of respiratory virus isolation in a community-wide surveillance program in Houston. Among adults, the number of cases of pneumococcal bacteremia peaked in midwinter and declined strikingly in midsummer, indicating a high degree of inverse correlation with the ambient temperature. We detected significant correlations between the occurrence of pneumococcal disease and the isolation of respiratory syncytial virus (P < .001), influenza virus (P < .001), and all viruses except influenza virus (P < .001), as well as with air pollution, as measured by SO2 levels (P < .001). In contrast, the rate of invasive pneumococcal disease among infants and children was relatively more sustained from October through May, with a notable decrease in summer months; the incidence of pneumococcal disease was therefore less strongly correlated with cold weather and less closely associated with the isolation of respiratory syncitial virus or influenza virus. However, pneumococcal disease among infants and children was associated with isolation of these viruses after a 4-week lag period as well as with isolation of adenovirus and ragweed pollen counts. The finding, with regard to children, that correlations tended to be stronger for events that occurred 1 month previously than for those that occurred contemporaneously is consistent with the concept that viral or allergic events predispose to otitis media with effusion, which becomes suppurative and leads to pneumococcal bacteremia or meningitis. For adults, a more immediate predisposition to pneumococcal pneumonia and bacteremia because of viral infection or air pollution was suggested.

Prospective virologic surveillance has defined two influenza epidemics representing the fifth and sixth outbreaks attributed to H3N2 viruses since the prototype, A/Hong Kong/68 ((H3N2), emerged in 1968. The 1975 epidemic was caused by influenza A/Port Chalmers and yielded an estimated attack rate of 9 per cent; the second, attributed to influenza A/Victoria, produced an explosive outbreak, with an estimated attack rate of 18 per cent in 1976. The highest morbidity occurred in preschool children, with an estimated attack rate of over 30 per cent. During the early stages of both epidemics there was a predominance of cases among school-aged children, and school absenteeism peaked earlier than other nonvirologic indexes. These observations support the concept of rapid dissemination of influenza among schoolchildren and suggest that control of epidemic influenza might be facilitated by prophylaxis for that age group and other accessible, healthy populations.