Conference Paper: Efficacy and effectiveness of trivalent inactivated influenza vaccination against confirmed influenza, acute respiratory illness, and medically attended acute respiratory illness

TitleEfficacy and effectiveness of trivalent inactivated influenza vaccination against confirmed influenza, acute respiratory illness, and medically attended acute respiratory illness
Authors
Issue Date2012
PublisherISIRV.
Citation
ISIRV International Conference on Seasonal and Pandemic Influenza, Munich, Germany, 5-8 September 2012. In Incidence, Severity, and Impact 2012: poster presentations, 2012, p. 58-59, abstract S2-P51 How to Cite?
AbstractBACKGROUND: Trivalent inactivated influenza vaccination (TIV) has moderate to good efficacy in preventing laboratory-confirmed influenza infections in children. Cost-effectiveness calculations also require estimates of the incidence of influenza and the efficacy of vaccination against clinical outcomes. We estimated the impact of influenza in a large household cohort in Hong Kong in 2009-2010 and the direct efficacy of influenza vaccination. METHODS: 796 children 6-17 years of age were randomized to receive either 1 dose of TIV or normal saline as placebo. Subjects and their household members were followed up for approximately a year and monitored for signs and symptoms (body temperature ≥37.8° C, chills, headache, sore throat, cough, coryza, or myalgia) of acute respiratory illness (ARI) and associated visits to outpatient healthcare services through biweekly telephone follow-up, daily symptom diary, and self-reporting to study hotline as soon as their ARI started. Nose and throat swabs were collected for reverse transcription polymerase chain reaction (RT-PCR) testing from all household members once any of the members in the same household showed at least 2 of the ARI signs or symptoms. Serology was collected periodically. RESULTS: Children who were randomized to receive TIV had lower rates of RT-PCR−confirmed (0.07 per person-year; 95% CI, 0.04-0.10) influenza virus infections compared with children who received placebo (0.11 per person-year; 95% CI, 0.08-0.16). However, the crude rates of ARI (1.81 per person-year; 95% CI, 1.68-1.94) and medically attended ARI (0.93 per person-year, 95% CI, 0.83-1.02) were not significantly different in TIV and placebo recipients. The analyses were repeated in household contacts with similar observations, after adjusting for potential confounders. Approximately 40% of unvaccinated children and 17% of unvaccinated adults had serologic evidence of influenza virus infection during follow-up. CONCLUSION: Influenza had a substantial impact on adults and children in Hong Kong during our study period. While TIV reduced the risk of laboratory-confirmed influenza virus infection in children, it had little effect on the overall rates of ARI and medically attended ARI. One possible explanation is virus interference, and analysis of noninfluenza respiratory virus infections would help to clarify the situation. Analyses that focus on the effect of vaccination on laboratory-confirmed influenza may overestimate the benefit of vaccination.
DescriptionPoster Presentations: S2-P51
Persistent Identifierhttp://hdl.handle.net/10722/182168

 

DC FieldValueLanguage
dc.contributor.authorNg, Sen_US
dc.contributor.authorIp, DKMen_US
dc.contributor.authorFang, VJen_US
dc.contributor.authorChan, KHen_US
dc.contributor.authorChiu, SSSen_US
dc.contributor.authorLeung, GMen_US
dc.contributor.authorPeiris, Men_US
dc.contributor.authorCowling, BJen_US
dc.date.accessioned2013-04-17T07:28:09Z-
dc.date.available2013-04-17T07:28:09Z-
dc.date.issued2012en_US
dc.identifier.citationISIRV International Conference on Seasonal and Pandemic Influenza, Munich, Germany, 5-8 September 2012. In Incidence, Severity, and Impact 2012: poster presentations, 2012, p. 58-59, abstract S2-P51en_US
dc.identifier.urihttp://hdl.handle.net/10722/182168-
dc.descriptionPoster Presentations: S2-P51-
dc.description.abstractBACKGROUND: Trivalent inactivated influenza vaccination (TIV) has moderate to good efficacy in preventing laboratory-confirmed influenza infections in children. Cost-effectiveness calculations also require estimates of the incidence of influenza and the efficacy of vaccination against clinical outcomes. We estimated the impact of influenza in a large household cohort in Hong Kong in 2009-2010 and the direct efficacy of influenza vaccination. METHODS: 796 children 6-17 years of age were randomized to receive either 1 dose of TIV or normal saline as placebo. Subjects and their household members were followed up for approximately a year and monitored for signs and symptoms (body temperature ≥37.8° C, chills, headache, sore throat, cough, coryza, or myalgia) of acute respiratory illness (ARI) and associated visits to outpatient healthcare services through biweekly telephone follow-up, daily symptom diary, and self-reporting to study hotline as soon as their ARI started. Nose and throat swabs were collected for reverse transcription polymerase chain reaction (RT-PCR) testing from all household members once any of the members in the same household showed at least 2 of the ARI signs or symptoms. Serology was collected periodically. RESULTS: Children who were randomized to receive TIV had lower rates of RT-PCR−confirmed (0.07 per person-year; 95% CI, 0.04-0.10) influenza virus infections compared with children who received placebo (0.11 per person-year; 95% CI, 0.08-0.16). However, the crude rates of ARI (1.81 per person-year; 95% CI, 1.68-1.94) and medically attended ARI (0.93 per person-year, 95% CI, 0.83-1.02) were not significantly different in TIV and placebo recipients. The analyses were repeated in household contacts with similar observations, after adjusting for potential confounders. Approximately 40% of unvaccinated children and 17% of unvaccinated adults had serologic evidence of influenza virus infection during follow-up. CONCLUSION: Influenza had a substantial impact on adults and children in Hong Kong during our study period. While TIV reduced the risk of laboratory-confirmed influenza virus infection in children, it had little effect on the overall rates of ARI and medically attended ARI. One possible explanation is virus interference, and analysis of noninfluenza respiratory virus infections would help to clarify the situation. Analyses that focus on the effect of vaccination on laboratory-confirmed influenza may overestimate the benefit of vaccination.-
dc.languageengen_US
dc.publisherISIRV.en_US
dc.relation.ispartofIncidence, Severity, and Impact 2012: poster presentationsen_US
dc.titleEfficacy and effectiveness of trivalent inactivated influenza vaccination against confirmed influenza, acute respiratory illness, and medically attended acute respiratory illnessen_US
dc.typeConference_Paperen_US
dc.identifier.emailNg, S: sophiang@hku.hken_US
dc.identifier.emailIp, DKM: dkmip@hku.hken_US
dc.identifier.emailFang, VJ: vickyf@hku.hken_US
dc.identifier.emailChan, KH: chankh2@hkucc.hku.hken_US
dc.identifier.emailChiu, SSS: ssschiu@hku.hken_US
dc.identifier.emailLeung, GM: gmleung@hku.hken_US
dc.identifier.emailPeiris, M: malik@hkucc.hku.hken_US
dc.identifier.emailCowling, BJ: bcowling@hku.hk-
dc.identifier.authorityIp, DKM=rp00256en_US
dc.identifier.authorityChiu, SSS=rp00421en_US
dc.identifier.authorityLeung, GM=rp00460en_US
dc.identifier.authorityPeiris, M=rp00410en_US
dc.identifier.authorityCowling, BJ=rp01326en_US
dc.description.naturelink_to_OA_fulltext-
dc.identifier.hkuros213765en_US
dc.identifier.spage58en_US
dc.identifier.epage59en_US
dc.publisher.placeGermany-

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