Importance of background rates of disease in assessment of vaccine safety during mass immunisation with pandemic H1N1 influenza vaccines.
Because of the advent of a new influenza A H1N1 strain, many countries have begun mass immunisation programmes. Awareness of the background rates of possible adverse events will be a crucial part of assessment of possible vaccine safety concerns and will help to separate legitimate safety concerns from events that are temporally associated with but not caused by vaccination. We identified background rates of selected medical events for several countries. Rates of disease events varied by age, sex, method of ascertainment, and geography. Highly visible health conditions, such as Guillain-Barré syndrome, spontaneous abortion, or even death, will occur in coincident temporal association with novel influenza vaccination. On the basis of the reviewed data, if a cohort of 10 million individuals was vaccinated in the UK, 21.5 cases of Guillain-Barré syndrome and 5.75 cases of sudden death would be expected to occur within 6 weeks of vaccination as coincident background cases. In female vaccinees in the USA, 86.3 cases of optic neuritis per 10 million population would be expected within 6 weeks of vaccination. 397 per 1 million vaccinated pregnant women would be predicted to have a spontaneous abortion within 1 day of vaccination.
Black
Steven
S
Center for Global Health and Division of Infectious Diseases, Cincinnati Children's Hospital, Cincinnati, OH, USA. Electronic address: Steven.Black1@cchmc.org.
Eskola
Juhani
J
National Institute for Health and Welfare, Helsinki, Finland.
Siegrist
Claire-Anne
CA
Center for Vaccinology and Neonatal Immunology, Department of Pediatrics, University of Geneva, Geneva, Switzerland.
Halsey
Neal
N
Institute for Vaccine Safety, Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA.
MacDonald
Noni
N
Division of Infectious Diseases, Department of Pediatrics, Dalhousie University, Halifax, NS, Canada.
Law
Barbara
B
Vaccine Safety Section, Centre for Immunization and Respiratory Infectious Diseases, Public Health Agency of Canada, Ottawa, ON, Canada.
Miller
Elizabeth
E
Health Protection Agency, Centre for Infections, Colindale, London, UK.
Andrews
Nick
N
Health Protection Agency, Centre for Infections, Colindale, London, UK.
Stowe
Julia
J
Health Protection Agency, Centre for Infections, Colindale, London, UK.
Salmon
Daniel
D
National Vaccine Program Office, Department of Health and Human Services, Washington, DC, USA.
Vannice
Kirsten
K
National Vaccine Program Office, Department of Health and Human Services, Washington, DC, USA.
Izurieta
Hector S
HS
Center for Biologics Evaluation and Research, Food and Drug Administration, Rockville, MD, USA.
Akhtar
Aysha
A
Center for Biologics Evaluation and Research, Food and Drug Administration, Rockville, MD, USA.
Gold
Mike
M
Discipline of Paediatrics, School of Paediatrics and Reproductive Health, University of Adelaide, SA, Australia.
Oselka
Gabriel
G
Department of Pediatrics, Faculty of Medicine, University of São Paulo, São Paulo, Brazil.
Zuber
Patrick
P
Quality, Safety and Standards Team, World Health Organization, Geneva, Switzerland.
Pfeifer
Dina
D
Quality, Safety and Standards Team, World Health Organization, Geneva, Switzerland.
Vellozzi
Claudia
C
Immunization Safety Office, Centers for Disease Control and Prevention, Atlanta, GA, USA.
D000293:Adolescent; D000328:Adult; D002675:Child, Preschool; D005260:Female; D020275:Guillain-Barre Syndrome; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype / Q000276:immunology*; D007252:Influenza Vaccines / Q000009:adverse effects / Q000592:standards*; D008297:Male; D032541:Mass Vaccination / Q000009:adverse effects; D009103:Multiple Sclerosis / Q000209:etiology; D009188:Myelitis, Transverse / Q000209:etiology; D009443:Neuritis / Q000209:etiology; D007752:Obstetric Labor, Premature / Q000209:etiology; D009902:Optic Neuritis / Q000209:etiology; D011247:Pregnancy
D007252:Influenza Vaccines