Children vaccinated against influenza are significantly less likely to experience serious complications from the virus that could land them in hospital, new research from Public Health Ontario (PHO) and the Institute for Clinical Evaluative Sciences (ICES) has found.
Published in the Nov. 17 issue of PLOS ONE, the study found that young children who were fully vaccinated against influenza saw their risk of hospitalization due to influenza infection drop by 60 per cent overall. Even for children partially vaccinated against influenza (i.e., those who received one dose of influenza vaccine during their first influenza season), risk of hospitalization due to influenza dropped by 39 per cent.
"Influenza can cause serious illness, especially in young children, but there hasn't been a lot of research that has examined the magnitude of the influenza vaccine's effectiveness at preventing kids from getting really sick and being hospitalized," says Dr. Jeff Kwong, a scientist in Applied Immunization Research and Evaluation at PHO and a senior scientist at ICES. Dr. Kwong is the senior author of the research paper.
"This research paper helps fill that gap by showing how effective the influenza vaccine can be at protecting young kids against serious complications from influenza infections," adds Dr. Kwong.
The researchers examined nearly 10,000 Ontario hospital records of children aged six months to under five years where a respiratory specimen was collected and tested for influenza; 12.8 per cent showed lab-confirmed influenza. The scientists included four influenza seasons - 2010-11 to 2013-14 - and broke the data down to compare children who were fully vaccinated, partially vaccinated and those who didn't get the vaccine. They also compared variations by age group and the circulating influenza strains each season.
Overall, fully vaccinated children aged two- to four-years-old saw their risk of hospitalization due to influenza drop by 67 per cent while those aged six to 23 months saw their risk drop by 48 per cent.
"These results show that flu vaccines are effective at preventing influenza hospitalizations in young kids, and this extended to those who received their vaccination in two consecutive seasons. This contributes to the evidence that this group should be receiving their seasonal vaccine annually to prevent such serious outcomes," says Sarah Buchan, a PhD candidate at the University of Toronto and the study's lead author.
This research was conducted in collaboration with scientists from PHO, ICES, the University of Toronto, the Hospital for Sick Children, the Children's Hospital of Eastern Ontario, North York General Hospital, Sinai Health System, William Osler Health System, Sunnybrook Health Sciences Centre, McMaster University, London Health Sciences Centre, and the Newfoundland and Labrador Public Health Laboratory.
Public Health Ontario is a Crown corporation dedicated to protecting and promoting the health of all Ontarians and reducing inequities in health. Public Health Ontario links public health practitioners, front-line health workers and researchers to the best scientific intelligence and knowledge from around the world. For the latest PHO news, follow us on Twitter: @publichealthON.
The Institute for Clinical Evaluative Sciences (ICES) is an independent, non-profit organization that uses population-based health information to produce knowledge on a broad range of health care issues. Our unbiased evidence provides measures of health system performance, a clearer understanding of the shifting health care needs of Ontarians, and a stimulus for discussion of practical solutions to optimize scarce resources. ICES knowledge is highly regarded in Canada and abroad, and is widely used by government, hospitals, planners, and practitioners to make decisions about care delivery and to develop policy. For the latest ICES news, follow us on Twitter: @ICESOntario
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