A cohort of 3000 adults is followed to evaluate the effectiveness of the monovalent 2009 H1N1 vaccines used 2009-2010 and seasonal influenza vaccines used 2010-2011 in preventing the first laboratory-confirmed 2009 H1N1 influenza during the influenza season 2010-11.
In the beginning of the study, changes in the background information collected in the original study (conducted 2009-2010) are asked with a questionnaire. Information on influenza vaccinations is collected with vaccination cards and monthly short message service (SMS), and verified in registers, if needed. If an epidemic caused by the 2009 H1N1 virus starts in Finland, the participants are asked to actively report symptoms of influenza like illnesses (ILI). The symptoms are also monitored by weekly SMS. In case of ILI, nasal and oral swabs are collected to verify the 2009 H1N1 influenza cases. Paired serum samples are collected at the acute on convalescence phase of the disease. The occurrence of laboratory-confirmed 2009 H1N1 influenza cases is compared between vaccinated and not (yet) vaccinated persons.
Study Type
OBSERVATIONAL
Enrollment
2,351
National Institute for Health and Welfare
Tampere, Finland
To determine the effectiveness of 2009 H1N1 influenza vaccination in preventing the first episode of laboratory-confirmed influenza caused by the 2009 H1N1 virus during the season 2010-11 among vaccinated adults as compared to unvaccinated adults
Time frame: September 2010 to April 2011
To explore the ability of different vaccination regimens to prevent 2009 H1N1 influenza
Time frame: September 2010 to April 2011
To explore the effectiveness of the 2009 H1N1 vaccines in subgroups stratified by age
Time frame: September 2010 to April 2011
To evaluate the incidence, severity and possible complications of laboratory-confirmed infection with the 2009 H1N1 influenza virus
Time frame: September 2010 to April 2011
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