1. Influenza virus infections from 0 to 2 years of age: A birth cohort study
- Author
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Laura Toivonen, Matti Waris, Tamara Teros-Jaakkola, Linnea Schuez-Havupalo, Ilkka Julkunen, Ville Peltola, and Sinikka Karppinen
- Subjects
0301 basic medicine ,Microbiology (medical) ,Pediatrics ,medicine.medical_specialty ,Influenza vaccine ,lcsh:QR1-502 ,Virus ,lcsh:Microbiology ,03 medical and health sciences ,Influenza A Virus, H1N1 Subtype ,0302 clinical medicine ,Adjuvants, Immunologic ,Influenza, Human ,Pandemic ,Humans ,Immunology and Allergy ,Medicine ,Prospective Studies ,030212 general & internal medicine ,Respiratory Tract Infections ,Finland ,General Immunology and Microbiology ,Respiratory tract infections ,business.industry ,Incidence ,Influenza A Virus, H3N2 Subtype ,Incidence (epidemiology) ,Vaccination ,ta1183 ,Infant ,virus diseases ,General Medicine ,030112 virology ,ta3123 ,3. Good health ,Influenza B virus ,Treatment Outcome ,Infectious Diseases ,Influenza Vaccines ,Cohort ,Vaccine-preventable diseases ,Seasons ,business - Abstract
Background/purpose: Influenza vaccine has been recommended in Finland since 2007 for all children of 6–35 months of age and in 2009 for those ≥6 months against pandemic influenza. We investigated the incidence of influenza and vaccine effectiveness in a birth cohort of children in 2008–2011. Methods: We followed 923 children from birth to 2 years of age for respiratory tract infections. A nasal swab sample for PCR for influenza A and B viruses was taken at the onset of acute respiratory infections. Samples were collected either at the study clinic or at home by parents. Vaccination data was retrieved from the health registries. Results: Vaccination coverage of children aged 6–23 months was 22–47% against seasonal influenza and 80% against the A(H1N1)pdm09 virus in the pandemic season 2009–2010. During 3 influenza seasons, 1607 nasal swab samples were collected. Influenza was confirmed in 56 (6.1%) of 923 children (16 A(H1N1), 14 A(H3N2), and 26 B viruses). The incidence of influenza was 5.1% in 2008–2009, 2.7% in 2009–2010, and 5.0% in 2010–2011. Effectiveness of the adjuvanted vaccine against the pandemic influenza A(H1N1)pdm09 was 97% (95% confidence interval, 76–100%). Three children with influenza were hospitalized. Conclusion: The yearly incidence of seasonal influenza was 5% in this cohort of very young children with variable influenza vaccine coverage. Adjuvanted vaccine against the pandemic influenza was highly effective. Both seasonal and pandemic influenza cases were mostly non-severe. Keywords: Children, Infant, Influenza, Pandemic influenza, Vaccination, Vaccine-preventable diseases
- Published
- 2019