IN the midst of this year’s unusually long influenza season, high number of confirmed cases and media attention on the spate of influenza-related deaths in residential aged care centres, the President of the Australian Medical Association Dr Michael Gannon proclaimed that it was “utterly irresponsible” for aged care workers not to be vaccinated against flu. Moreover, Health Minister Greg Hunt has promised their mandatory vaccination from next season.
In my opinion, calls for flu vaccination of people who are fit and healthy are horribly misguided.
There is no conclusive evidence that vaccinating health care workers meaningfully benefits patients, with one recent review suggesting that up to 32 000 health care workers would need to be vaccinated to prevent a single death in health care facilities generally, and another finding no benefit in the number of cases, complications, or all-cause mortality in patients of long term aged care facilities specifically.
Influenza is highly infectious before the carrier even feels sick, and the virus can survive on doorknobs for up to 48 hours. Should facilities be requiring all visitors and patients to be vaccinated before entering? Do we really think that outbreaks in health care settings could otherwise be prevented or contained when there is no herd immunity in the general population?
The influenza vaccine has serious problems that have (rightly) kept it off the normal vaccination schedule. It is funded for, and targeted to, the most medically vulnerable people because that is when the benefits specific to those vaccinated clearly outweigh the risks.
However, the flu vaccine is not great at preventing influenza infection. The choice of which flu virus strains to cover each season sometimes turns out to be wrong, while vaccine effectiveness is typically less than 50%, with a waning protection that lasts for far less than a year, often for only a few months (here and here).
This season, early indications are that the vaccine’s effectiveness could be as low as 15% in Australia, due in part to antigenic drift of the predominant H3N2 strain since it was selected for the formula early in the year. As a result, we have had an unusually high number of influenza A cases even among those who had been vaccinated.
How would any (future) herd immunity not be as fleeting as vaccine effectiveness?
Getting the flu vaccine regularly simply postpones susceptibility to the covered strains and may even further reduce vaccine effectiveness, while actually coming down with the flu when healthy results in decades’ (often lifelong) protection. Getting the flu infection also results in further protection against dozens, potentially hundreds of related strains (as in the case of the 2009 influenza H1N1 pandemic), while vaccination has been only sporadically and inconsistently found to confer a much weaker, short term cross-immunity. Indeed, prior infection with related influenza A strains decades earlier is believed to be the reason that the elderly were not at highrisk to the 2009 strain in the first place (here, here, here, here, and here).
Moreover, there is a poor understanding of the risks of mass vaccination on influenza strain selection, virility, and vaccine resistance — which may be compared with the resurgence of whooping cough in the general population, and its association with waning immunity to the new predominant pertussis strains increasingly seen in vaccinated people, since the switch to acellular formulas in the 1990s (here and here).
The expected outcome of regular flu vaccination in healthy people is therefore increased morbidity later in life, when protection is needed the most (ie, after not having had many of the “common” influenza infections for decades, there is little resistance to them or their relatives once people are old and frail), with unknown risks to future vaccine effectiveness and from induced strain selection in a highly mutating class of viruses.
Forced medication should have a clear and significant expected net benefit. Influenza vaccination simply does not fit the bill. For long term health care facilities such as nursing homes, it makes sense to improve vaccine responsiveness in the patients themselves (eg, through improved rates, timing, dosage and adjuvant formulation), not to coerce an increased risk of morbidity onto health care workers.
Dr Randal Pittelli is a full-time rural generalist locum with a special interest in aeromedical retrieval. Before medicine he conducted research in behavioral toxicology following a BA in mathematics.
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