Challenge of conducting a placebo-controlled randomized efficacy study for influenza vaccine in a season with low attack rate and a mismatched vaccine B strain: a concrete example
| Autor: | Veronika Wertzova, Jeanne-Marie Devaster, Pascale Van Belle, Eva Kaliskova, Bruce L. Innis, Helena Jirincova, Jiří Beran, Martina Havlíčková, Jiří Havlík, Karel Honegr, Varsha K. Jain |
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| Rok vydání: | 2009 |
| Předmět: |
Adult
Male Adolescent Influenza vaccine Attack rate Hemagglutinin Glycoproteins Influenza Virus Biology Antibodies Viral medicine.disease_cause lcsh:Infectious and parasitic diseases law.invention Young Adult Influenza A Virus H1N1 Subtype Double-Blind Method Randomized controlled trial law Influenza Human Influenza A virus medicine Sore throat Humans lcsh:RC109-216 Czech Republic Influenza-like illness Viral culture Influenza A Virus H3N2 Subtype Vaccine efficacy Virology Influenza B virus Infectious Diseases Vaccines Inactivated Influenza Vaccines Female medicine.symptom Research Article |
| Zdroj: | BMC Infectious Diseases, Vol 9, Iss 1, p 2 (2009) BMC Infectious Diseases |
| ISSN: | 1471-2334 |
| DOI: | 10.1186/1471-2334-9-2 |
| Popis: | Background Our aim was to determine the efficacy of a trivalent inactivated split virus influenza vaccine (TIV) against culture-confirmed influenza A and/or B in adults 18 to 64 years of age during the 2005/2006 season in the Czech Republic. Methods 6203 subjects were randomized to receive TIV (N = 4137) or placebo (N = 2066). The sample size was based on an assumed attack rate of 4% which provided 90% power to reject the hypothesis that vaccine efficacy (VE) was ≥ 45%. Cases of influenza like illness (defined as fever (oral temperature ≥37.8°C) plus cough and/or sore throat) were identified both by active (biweekly phone contact) and passive (self reporting) surveillance and nasal and throat swabs were collected from subjects for viral culture. Results TIV was well tolerated and induced a good immune response. The 2005/2006 influenza season was exceptionally mild in the study area, as it was throughout Europe, and only 46 culture-confirmed cases were found in the study cohort (10 influenza A and 36 influenza B). Furthermore among the B isolates, 35 were identified as B/Hong Kong 330/2001-like (B/Victoria/2/87 lineage) which is antigenically unrelated to the vaccine B strain (B/Yamagata/16/88 lineage). The attack rate in the vaccine group (0.7%) was not statistically significantly different from the attack rate in the placebo group (0.9%). Conclusion Due to the atypical nature of the influenza season during this study we were unable to assess TIV efficacy. This experience illustrates the challenge of conducting a prospective influenza vaccine efficacy trial during a single season when influenza attack rates and drift in circulating strains or B virus lineage match can be difficult to estimate in advance. Trial Registration Clinical trial registery: NCT00197223. |
| Databáze: | OpenAIRE |
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