# 4416
The recent push to vaccinate children against seasonal influenza every year is based, in part, on the idea that kids are very efficient spreaders of the virus – and that if you can reduce their susceptibility to infection – you can reduce the influenza burden on the entire community.
Today we’ve a new study out of Canada that seems to support this theory, suggesting that vaccinating kids helps protect the entire community.
Helen Branswell of the Canadian Press brings us the details, and I’ve included the NIAID press release as well. Follow the link to read Helen’s article in its entirety.
Want to reduce amount of flu in adults? Vaccinate kids, study shows
By Helen Branswell Medical Reporter (CP) – 2 hours ago
TORONTO — A landmark study looking at how to limit the spread of influenza has shown what experts have long believed but hadn't until now proved: Giving flu shots to kids helps protect everyone in a community from the virus.
The study, led by Dr. Mark Loeb of McMaster University in Hamilton, Ont., showed the risk of catching the flu was lowered by nearly 60 per cent in communities where a substantial portion of kids aged three to 15 got flu shots.
That level of indirect protection is nearly as good as what healthy adults might expect from getting a flu shot themselves and is perhaps better than what a senior with a waning immune system might expect from a flu vaccination.
Vaccinating Children against Flu Helps Protect Wider Community
Trial Results in Rural Canadians Show Effect of Herd Immunity
WHAT:
Results of a clinical trial conducted in a largely self-contained religious community during the 2008-09 influenza season show that immunizing children against seasonal influenza can significantly protect unvaccinated community members against influenza as well. The study was conducted to determine if immunized children could act as a barrier to limit the spread of influenza to the wider, unvaccinated community, a concept known as herd immunity.
Researchers recruited volunteers from 46 Canadian Hutterite religious colonies that have limited contact with surrounding, non-Hutterite populations. A total of 947 children between 36 months to 15 years of age participated in the trial; 502 children in 22 colonies received 2008-09 seasonal influenza vaccine, while 445 youth in the other colonies received hepatitis A vaccine. The hepatitis A vaccine served as a control vaccine for comparison.
In the six months after the children were vaccinated, 119 of 2,326 unvaccinated community members (who were of all ages) developed laboratory confirmed cases of influenza. Of these, 80 of 1,055 were from colonies where children received hepatitis vaccine, while 39 of 1,271 were from colonies where children received the influenza vaccine.
The researchers found that influenza vaccination was 61 percent effective at indirectly preventing illness—that is, protecting via herd immunity—in unvaccinated individuals if they lived in a colony where approximately 80 percent of the children had received flu vaccine. The findings, they write, “...offer experimental proof to support selective influenza immunization of school aged children…to interrupt influenza transmission. Particularly, if there are constraints in quantity and delivery of vaccine, it may be advantageous to selectively immunize children in order to reduce community transmission of influenza.”
Mark Loeb, M.D., of McMaster University, Hamilton, Ontario, led the trial. The research was funded in part by the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health, and by the Canadian Institutes for Health Research.
Visit the NIAID Web site to see an illustration showing how vaccination generates herd immunity.
ARTICLE:
M Loeb et al. Effect of influenza vaccination of children on infection rates in Hutterite communities. JAMA 303:943-50 DOI: 10.1001/jama.303.10.943 (2010).
Credit NIAID
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