Earlier this week we noted that evidence supporting the efficacy of flu shots specifically for health care workers has been weak.
Much of the anti-flu shot sentiment is based on a number of reviews by the Cochrane Collaboration (CC). The CC is a respected non-profit network of 28,000 people over 100 countries that produce reviews to help decision-makers make evidence-based decisions on health care.
The CC has turned out a number of papers on the efficacy of flu shots as a preventative measure in health care settings.
What the reviews most commonly state is that there is little research free of bias (that is, not sponsored by vaccine companies who have an interest in the outcome) to come to any evidence-based conclusion. Cochrane notes the specific need for high-quality randomized trials.
The Cochrane Review states there are more than 200 viruses that cause influenza or influenza-like illness which produce the same symptoms – fever, headache, aches and pains, cough and runny noses. At best vaccine may be effective on 10 per cent of these viruses. Without a lab test, it is impossible to tell them apart.
Most people who get these symptoms go home to bed for a few days, they don’t necessarily run to get a lab test.
Under ideal conditions, you have to vaccinate 33 adults to prevent one set of influenza symptoms. In average conditions, it’s more like 100 adults.
Nor is there evidence to suggest there is much risk from the vaccine itself. The risk of getting Guillian-Barré syndrome is remote – one in every million vaccinations according to Cochrane. The ingredients will prompt anaphylaxis in some – particularly those with sensitivities to egg protein. Egg is one of the more common food allergies.
One of the difficulties of assessing the impact health care workers have on their patients is whether the flu vaccine alone would make a difference. These would have to be set aside from other infection control measures, including hand washing, face masks, early detection using nasal swabs, outbreak quarantines and avoiding new admissions, prompt use of antivirals, and asking healthcare workers with an influenza-like illness not to show up for work.
Cochrane concludes that there is no evidence that flu shots alone would make a difference.
In British Columbia health care workers have a choice in the so-called “mandatory policy” – get the shot or wear a mask.
Tom Jefferson, one of the authors of the Cochrane Review, ripped into BC’s Dr. Perry Kendall, one of the defenders of the policy.
“It is not my place to judge the policies underway in British Columbia, but coercion and forcing public ridicule on human beings (for example by forcing them to wear distinctive badges or clothing) is usually the practice of tyrants,” Jefferson wrote in a letter published in the Vancouver Sun.
Kendall and seven other doctors replied that the Cochrane Collaboration has a very narrow standard of evidence, noting widespread support for the vaccine – but not necessarily mandatory requirement – from groups as diverse as the BC College of Physicians and Surgeons and the Canadian Nurses’ Association to the Society for Healthcare Epidemiology of America.
“The great majority of public health and influenza experts across North America and the UK are convinced that the weight of evidence favours the protective effect of influenza vaccines,” Kendall and the other doctors write. “Far from being a ‘tyrannical’ notion, professional bodies from every health care discipline have gone on record as stating patient protection through influenza vaccination is part of a ‘duty of care.’”
In yesterday’s Globe and Mail, Alan Cassels, a drug-industry researcher at the University of Victoria, said “the science should determine whether it’s the right thing to do, and there is little evidence that (vaccination) prevents transmission from health workers to patients.”
While the BC Nurses’ Union is grieving the “flu shot or mask” policy in that province, they do still recommend that their members voluntarily receive the flu shot.