ABSTRACT
Understanding household transmission of the pandemic influenza A(H1N1)2009 virus, including risk factors for transmission, is important for refining public health strategies to reduce the burden of the disease. During the influenza season of 2009 we investigated transmission of the emerging virus in 595 households in which the index case was the first symptomatic case of influenza A(H1N1)2009. Secondary cases were defined as household contacts with influenza-like illness (ILI) or laboratory-confirmed influenza A(H1N1)2009, occurring at least one day after but within seven days following symptom onset in the index case. ILI developed in 231 of the 1,589 household contacts, a secondary attack rate of 14.5% (95% confidence interval (CI): 12.916.4). At least one secondary case occurred in 166 of the 595 households (a household transmission rate of 27.9%; 95% CI: 24.531.6).Of these, 127 (76.5%) households reported one secondary case and 39 (23.5%) households reported two or more secondary cases. Secondary attack rates were highest in children younger than five years (p=0.001), and young children were also more efficient transmitters (p=0.01). Individual risk was not associated with household size. Prophylactic antiviral therapy was associated with reduced transmission (p=0.03). The secondary attack rate of ILI in households with a confirmed pandemic influenza A(H1N1)2009 index case was comparable to that described previously for seasonal influenza.
Subject(s)
Family Characteristics , Influenza A Virus, H1N1 Subtype/isolation & purification , Influenza, Human/epidemiology , Influenza, Human/transmission , Adolescent , Adult , Age Distribution , Antiviral Agents/therapeutic use , Child , Child, Preschool , Contact Tracing , Female , Humans , Infant , Influenza, Human/diagnosis , Influenza, Human/drug therapy , Influenza, Human/virology , Logistic Models , Male , Middle Aged , Pandemics , Polymerase Chain Reaction , Western Australia/epidemiology , Young AdultABSTRACT
OBJECTIVES: To assess the frequency and nature of requests for post-exposure prophylaxis following nonoccupational exposure (NONOPEP) to HIV and to describe variations in practice and opinions on the need for its administration at UK genitourinary medicine (GUM) clinics. METHOD: A retrospective survey was carried out of physicians representative of all UK GUM clinics using self completed questionnaires requesting information for January to December 1999. The number of requests for NONOPEP, reasons for the requests, the number prescribed, and physician opinions regarding the justification for its administration were noted. RESULTS: The number of requests and prescriptions for NONOPEP increased fourfold and sevenfold respectively in comparison with a survey from 1997. Of 242 requests, 130 people were prescribed NONOPEP. Half the requests followed sexual exposures between known HIV discordant couples. Requests for NONOPEP were received by 56 of 132 (42%) clinics, with nine clinics receiving over half of them (145/242, 60%). Similarly, over half the prescriptions for NONOPEP (83/130, 64%) were given by six of 39 prescribing clinics. Most physicians thought that post-exposure prophylaxis (PEP) was justified for people exposed to a known HIV positive source patient resulting from sexual assault or unprotected receptive anal or penovaginal sex. CONCLUSION: The use of NONOPEP has increased since the last survey and there is considerable variation between GUM clinics in practice and beliefs regarding administration of NONOPEP.
