title: Age-specific epidemic waves of influenza and respiratory syncytial virus in a subtropical city.
abstract: Both influenza and respiratory syncytial virus (RSV) are active throughout the year in subtropical or tropical regions, but few studies have reported on age-specific seasonal patterns of these viruses. We examined the age-specific epidemic curves of laboratory-confirmed cases of influenza A (subtyped into seasonal A(H1N1), A(H3N2), and pandemic virus A(H1N1)pdm09), influenza B and respiratory syncytial virus (RSV), in subtropical city Hong Kong from 2004 to 2013. We found that different types and subtypes of influenza showed similar two-peak patterns across age groups, with one peak in winter and another in spring/summer. Age differences were found in epidemic onset time and duration, but none could reach statistical significance (p > 0.05). Age synchrony was found in epidemic peak time for both cool and warm seasons. RSV showed less clear seasonal patterns and non-synchronized epidemic curves across age. In conclusion, age synchrony was found in influenza seasonal epidemics and the 2009 pandemic, but not in RSV. None of the age groups consistently appear as the driving force for seasonal epidemics of influenza and RSV in Hong Kong.
authors.affiliation: School of Nursing, The Hong Kong Polytechnic University.
authors.forename: Lin
authors.initials: L
authors.lastname: Yang
authors.affiliation: Department of Microbiology, The University of Hong Kong.
authors.forename: Kwok Hung
authors.initials: KH
authors.lastname: Chan
authors.affiliation: School of Nursing, The Hong Kong Polytechnic University.
authors.forename: Lorna K P
authors.initials: LK
authors.lastname: Suen
authors.affiliation: School of Public Health, The University of Hong Kong.
authors.forename: King Pan
authors.initials: KP
authors.lastname: Chan
authors.affiliation: 1] School of Public Health, The University of Hong Kong [2] School of Public Health, Fudan University.
authors.forename: Xiling
authors.initials: X
authors.lastname: Wang
authors.affiliation: School of Public Health, The University of Hong Kong.
authors.forename: Peihua
authors.initials: P
authors.lastname: Cao
authors.affiliation: Department of Applied Mathematics, The Hong Kong Polytechnic University.
authors.forename: Daihai
authors.initials: D
authors.lastname: He
authors.affiliation: School of Public Health, The University of Hong Kong.
authors.forename: J S Malik
authors.initials: JS
authors.lastname: Peiris
authors.affiliation: School of Public Health, The University of Hong Kong.
authors.forename: Chit Ming
authors.initials: CM
authors.lastname: Wong
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D002947:Cities; D006723:Hong Kong / Q000453:epidemiology; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D009980:Influenza A virus; D007251:Influenza, Human / Q000453:epidemiology* / Q000821:virology; D029524:Betainfluenzavirus; D008875:Middle Aged; D011159:Population Surveillance; D018357:Respiratory Syncytial Virus Infections / Q000453:epidemiology* / Q000821:virology; D012136:Respiratory Syncytial Viruses; D012621:Seasons; D014329:Tropical Climate; D055815:Young Adult