Public health officials walking a tightrope between massive demand for vaccines and intense public scrutiny of side effects now have a new standard for evaluating the safety of their vaccination programs.
Widespread concern about the 'swine flu' is prompting H1N1 vaccination programs in many countries -- seldom seen on such a massive scale. Meanwhile, media and Internet chatter about side effects may provoke public anxiety and result in a lower vaccination rate.
A new article published in The Lancet offers the first comprehensive, international baseline evidence about background illness and sudden death rates in healthy populations.
"In fact, vaccinations are one of the safest medical interventions that we have," says Noni MacDonald, a co-investigator on the study. "I am pro vaccine. Vaccines are held to a much higher standard for safety than drug treatments."
Dr. MacDonald is a professor in Dalhousie's Department of Pediatrics and a specialist in pediatric infectious diseases. In addition to working with the Canadian Center for Vaccinology, she is a past member of the World Health Organization's (WHO) Global Advisory Committee on Vaccine Safety.
"We recognized that because the H1N1 vaccine will be given to many, many millions of people that this type of a mass campaign is a relatively unique research opportunity," says Dr. MacDonald.
When little time elapses between a vaccination and a negative health impact, there is a tendency to correlate the two as cause and effect. An alternative explanation is that the close association is in timing only and not in cause.
Together with colleagues from across Canada, the United States, Brazil, Finland and Australia, she decided to look at unusual cases without specific known causes that tend to be attributed to vaccines. Background information was gathered about health conditions such as Guillain-Barre syndrome, Multiple Sclerosis and spontaneous abortions. The researchers also looked at cases of sudden unexplained death. These incidents are so uncommon that they are detected only when very large groups are studied.
As a result, they're able to identify the rate that these conditions occur in a given population when there is no ongoing vaccine campaign -- the 'coincident background cases.' With this new information, public health officials will be able to monitor reported cases of adverse reactions following a vaccination program and see if rates jump or stay the same.
The report's authors are primarily hoping to reach health care policy and decision makers with their findings.
"I think the public can be reassured that there is careful thought and evaluation of any adverse event that occurs around vaccination programs. All incidents are taken very seriously and great care is taken in the follow up assessments," says Dr. MacDonald.
- Avoiding panic in pandemics. The Lancet, (in press)
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