Canada has committed almost $500-million of our money to buy the H1N1 vaccine. It will cost at least as much again to get this vaccine into people's arms. Is this politics or good policy?
Recall how the voluminous pandemic plans said the greatest impact of a pandemic would be during the "first wave." Pandemics should hit hard and fast, sicken between 25 per cent and 35 per cent of the world's population and kill between two million and 20 million people. Our health-care system should be overwhelmed. Hard choices about rationing health care should follow. None of this has happened - not in Mexico, Manitoba or anywhere else.
Now, new concerns have been raised about a devastating "second wave" this winter, claiming we may have got off lightly with a spring "first wave." These new concerns predicate all planning for the fall. Influenza does indeed spread better when the weather is relatively cold and dry.
To get an idea of what the "second wave" will look like, let's consider what's just happened with H1N1 during the winter in the Southern Hemisphere's temperate countries (Australia, New Zealand, Chile and Argentina). They are now facing H1N1 full blast. Yet, these outbreaks have already passed their peaks. The World Health Organization has concluded that the severity there "generally appeared slightly worse than a normal influenza season." Indeed, the death rates in these countries are far lower than projected for even a mild pandemic. Globally, H1N1 is currently responsible for about one out of every 3,000 deaths.
We should expect H1N1 to be the dominant influenza virus in Canada next fall. In the Southern Hemisphere, H1N1 seems to have replaced the other seasonal influenza viruses. We should also expect, in the worst-case scenario, that the "second wave" of H1N1 will be "slightly worse than a normal influenza season." More likely, we should expect something even less severe because many Canadians have already been infected and are now immune. We should expect less illness than we saw in 2003 with the Fujian influenza strain.
Typically, the vast majority of deaths from seasonal influenza are in the elderly. H1N1 rarely infects people born before 1957, probably because they were exposed to a similar virus half a century ago. Thus we should expect fewer total deaths than usual. Furthermore, almost three-quarters of the deaths from H1N1 occur in people with chronic diseases.
This should advise a rational strategy for H1N1 immunization. Certainly, younger people with chronic diseases should be immunized. So should aboriginals living on first nations reserves, and perhaps others who live remote from medical care. We may see higher than usual mortality in these groups.
Who else needs to get the new vaccine? It's not clear yet.
It's not clear that health-care workers are really at much increased risk now that the "first wave" has passed. The concern that they will spread influenza to vulnerable elderly patients does not apply with H1N1. Furthermore, absenteeism during Australia's "first wave" has really been no worse than during a typical flu season. Absenteeism should be no different for Canadian health-care workers this fall.
Pregnant women do have a higher risk of serious complications from H1N1 than the general population. This is hardly a surprise. We have known for decades that influenza is worse in pregnancy. But four times a very small risk of dying is still a very small risk - not much more than one in 300,000 for all pregnant women in North America and probably much less for those without chronic illnesses. The risks and benefits of immunization (and of Tamiflu treatment for the symptomatic) need to be weighed individually for pregnant women.
The case for universal H1N1 immunization still needs to be made. If most people over 50 are immune, do they all need immunization? Do the benefits of immunization for healthy younger people outweigh the costs and potential risks? Can the vaccine even be delivered to large populations before the "second wave" has come and gone? These are all important unanswered questions.
What should Canada do with all of our vaccine? Perhaps give some to developing countries to immunize their high-risk populations, too. Meantime, we should figure out a sensible way forward based on evidence, not speculation.
Richard Schabas was Ontario's chief medical officer of health from 1987 to 1997. Neil Rau is an infectious diseases specialist and medical microbiologist in private practice in Oakville, Ont., and a lecturer at the University of Toronto.