Should you get a flu vaccine this winter?

Winter is finally upon us here in the southern hemisphere, and many of my clients have been asking me about flu vaccination. Fortunately, I don’t have to sift through the scientific literature all by myself to come up with advice on this matter; I can simply quote the findings of the Cochrane Collaboration on influenza vaccination.

For those of you not familiar with the Cochrane Collaboration, it is an international, not-for-profit organisation comprised of independent researchers – that is, they do not receive any funding from commercial sources, instead relying on international government agencies and charitable donations (commercial organisations such as pharmaceutical companies are specifically prohibited from making donations, under the Cochrane Collaboration’s Policy Manual).

The role of the Cochrane Collaboration is to establish an evidence base for health and medical care, by assessing the published literature (and unpublished trials, when available) to determine whether interventions such as surgery, medical drugs and nutritional supplements are effective at treating particular conditions. The work of the Cochrane Collaboration, which is published in Cochrane Reviews, is “internationally recognised as the benchmark for high quality information about the effectiveness of health care.”

So what is the Cochrane Collaboration’s verdict on flu vaccination? Separate Cochrane Reviews have been published on influenza vaccination in:

• Children,
• Healthy adults,
• The elderly, and
• Health care workers caring for institutionalised elderly people.

In every case, the reviewers concluded that the task of accurately assessing the effectiveness of flu vaccination was made next to impossible by the fact that the studies published by pharmaceutical companies were marred by poor methodological quality, multiple types of bias and in some cases, outright deceit:

“This review includes trials funded by industry. An earlier systematic review of 274 influenza vaccine studies published up to 2007 found industry-funded studies were published in more prestigious journals and cited more than other studies independently from methodological quality and size. Studies funded from public sources were significantly less likely to report conclusions favourable to the vaccines. The review showed that reliable evidence on influenza vaccines is thin but there is evidence of widespread manipulation of conclusions and spurious notoriety of the studies.”

Vaccines for preventing influenza in healthy children

Here is a summary of the key points in each Cochrane Review (quotation marks indicate a direct quote from the review; points without quotation marks are my paraphrases):

• “Inactivated vaccines in children aged two years or younger are not significantly more efficacious than placebo” – in other words, injecting your child with saline solution would protect them from the flu about as well as a flu vaccine [N.B. all seasonal flu vaccines used in Australia – Fluarix, Fluvax and Vaxigrip/Vaxigrip Junior – are inactivated].
• “Twenty-eight children over the age of six need to be vaccinated to prevent one case of influenza (infection and symptoms).”
• Flu vaccination does not prevent the transmission of influenza to others.
• There is no reliable evidence that giving kids flu shots reduces their number of sickness-related school absences.
• Flu vaccination does not reduce the rate of lower respiratory tract disease (e.g. pneumonia), drug prescriptions, or middle ear infections (or their consequences or socioeconomic impact).
• 47% of children given a placebo instead of a vaccine developed an upper respiratory tract infection during the follow-up period, compared to 53-70% of vaccinated children.
• “One specific brand of monovalent pandemic vaccine is associated with cataplexy [a sudden and transient episode of muscle weakness accompanied by full conscious awareness] and narcolepsy [a chronic neurological disorder inhibiting the brain’s ability to regulate sleep-wake cycles] in children and there is sparse evidence of serious harms (such as febrile convulsions) in specific situations.”
• “The main problem we encountered in interpreting studies… was that of high risk of bias: all included studies were poorly reported and contained either contradictions between data in figures, tables and text, or reported implausible events or showed evidence of reporting bias of one sort or another” – in other words, the authors of studies conducted by drug companies fudged data, left out important data, or just made stuff up to make the vaccine look good.
• Studies reporting that flu vaccination was effective are far more likely to be published than those reporting that it wasn’t; and studies finding that flu vaccines harmed children are far less likely to be published (and therefore don’t come to the attention of doctors or vaccine policy makers).
• Flu vaccines are not adequately tested for safety before being released onto the market: “This is the case of the 2010 TIV by CSL Ltd used mainly in Australia. One child in every 110, aged below five, vaccinated with the CSL vaccine had a febrile seizure. Australia suspended its use. These episodes highlight the insufficient regulatory attention to potential harms from influenza vaccines in children, as the registration trials for the CSL vaccine had been carried out on 162 children aged up to three years (Collignon 2010).”
• “It was surprising to find only one study of inactivated vaccine in children under two years, given current recommendations to vaccinate healthy children from six months of age in the USA, Canada, parts of Europe and Australia. If immunisation in children is to be recommended as a public health policy, large-scale studies assessing important outcomes, and directly comparing vaccine types are urgently required.”
• That single safety study of inactivated flu vaccine on children under 2 was conducted over 30 years ago (which means the test was done using a different vaccine than those used currently, since seasonal flu vaccines change annually depending on which flu strains are circulating) and in only 35 children! So much for governments’ and doctors’ reassurances that vaccines are safe – how can you possibly know if you haven’t tested them?
• The report’s authors were clearly concerned that vaccine manufacturers are not disclosing adverse reactions to flu vaccines that occur during clinical trials, as they stated: “Further safety data should also be collected or made available of the safety of vaccines in children, particularly inactivated vaccine in younger children. There is an immediate need to standardise safety outcome data… Honest and full disclosure of all safety data to researchers is also a priority.”
• And in summary: “National policies for the vaccination of healthy young children are based on very little reliable evidence… Decision makers’ attention to the vaccination of very young children is not supported by the evidence summarised in our review. Although there is a growing body of evidence showing the impact of influenza on hospitalisations and deaths of children, at present we could find no convincing evidence that vaccines can reduce mortality [death], hospital admissions, serious complications or community transmission of influenza.”

(Summarised from the Cochrane Review ‘Vaccines for preventing influenza in healthy children’.)

Vaccines for preventing influenza in healthy adults

• “In the relatively uncommon circumstance of vaccine matching the viral circulating strain and high circulation, 4% of unvaccinated people versus 1% of vaccinated people developed influenza symptoms … The corresponding figures for poor vaccine matching [the more common situation] were 2% and 1%.”
• “… under ideal conditions (vaccine completely matching circulating viral configuration) 33 healthy adults need to be vaccinated to avoid one set of influenza symptoms. In average conditions (partially matching vaccine) 100 people need to be vaccinated to avoid one set of influenza symptoms.”
• Flu vaccines reduce the risk of total “clinical” seasonal influenza (i.e. influenza-like illness) symptoms by “around 1%… the effect appears minimal. This is remarkable as healthy adults are the population in which inactivated vaccines perform best.”
• There was no difference in working days lost to the flu, hospital admissions or flu complication rates – including the risk of pneumonia – between those who received flu shots and those who didn’t.
• 1.6 additional cases of Guillain-Barré Syndrome (a major neurological condition leading to paralysis) occur for every million flu vaccines administered.
• The harms inflicted by flu vaccines are poorly understood because of inadequate research and documentation of adverse effects.
• The situation may be even worse than this report indicates, since “Fifteen of the 36 trials were funded by vaccine companies and four had no funding declaration. Our results may be an optimistic estimate because company-sponsored influenza vaccines trials tend to produce results favorable to their products and some of the evidence comes from trials carried out in ideal viral circulation and matching conditions and because the harms evidence base is limited.”
• “No RCTs [randomised controlled trials] assessing vaccination in pregnant women were found. The only evidence available comes from observational studies with modest methodological quality. On this basis, vaccination shows very limited effects: NNV [number needed to vaccinate in order to prevent one case] 92 (95% CI 63 to 201) against ILI [influenza-like illness] in pregnant women and NNV 27 (95% CI 18 to 185) against laboratory-confirmed influenza in newborns from vaccinated women.
• In summary: “The results of this review seem to discourage the utilisation of vaccination against influenza in healthy adults as a routine public health measure. As healthy adults have a low risk of complications due to respiratory disease, the use of the vaccine may be only advised as an individual protection measure against symptoms in specific cases.”

(Summarised from the Cochrane Reviews ‘Vaccines for preventing influenza in healthy adults’ and the 2014 update to that review.)

Vaccines for preventing influenza in the elderly

• “Due to the poor quality of the available evidence, any conclusions regarding the effects of influenza vaccines for people aged 65 years or older cannot be drawn.”
• “Our findings show that according to reliable evidence, the effectiveness of trivalent inactivated influenza vaccines in elderly individuals is modest, irrespective of setting, outcome, population and study design. Our estimates are consistently below those usually quoted for economic modelling or decision making” – that is, the benefits of flu vaccination in this age group are not sufficient to justify the cost of a vaccination program.

(Summarised from the Cochrane Review ‘Vaccines for preventing influenza in the elderly‘.)

Influenza vaccination for healthcare workers who work with the elderly

• “No effect was shown for specific outcomes: laboratory-proven influenza, pneumonia and death from pneumonia. An effect was shown for the non-specific outcomes of ILI [influenza-like illness], GP consultations for ILI and all-cause mortality in individuals ≥ 60. These non-specific outcomes are difficult to interpret because ILI includes many pathogens, and winter influenza contributes < 10% to all-cause mortality [dying from any cause] in individuals ≥ 60. The key interest is preventing laboratory-proven influenza in individuals ≥ 60, pneumonia and deaths from pneumonia, and we cannot draw such conclusions.”
• The studies analysed for this review “are at high risk of bias” because most of them were funded by pharmaceutical companies.
• And in summary: “We conclude that there is no evidence that vaccinating healthcare workers prevents laboratory-proven influenza, pneumonia, and death from pneumonia in elderly residents in long-term care facilities. Other interventions such as hand washing, masks, early detection of influenza with nasal swabs, anti-virals, quarantine, restricting visitors and asking healthcare workers with an influenza-like illness not to attend work might protect individuals over 60 in long-term care facilities and high quality randomised controlled trials testing combinations of these interventions are needed.”

(Summarised from the Cochrane Review ‘Influenza vaccination for healthcare workers who work with the elderly’.)

Let me reiterate here that the Cochrane Collaboration is not a bunch of dope-smoking, hemp sandal-wearing ‘alternative medicine’ types; it is the most authoritative institution in the world when it comes to providing an evidence base for medical care.

So when multiple Cochrane reviews point out that manufacturer-sponsored flu vaccine trials are biased and of poor methodological quality and even taking this into account, they still don’t show any advantage for getting a flu vaccine, you can take that to the bank!

If your doctor is keen for you to have a flu vaccine this year, ask if he or she has read the Cochrane reviews on the subject, and if so, what special circumstances apply in your case that might override the Cochrane recommendations.

If there are none, and yet your doctor is still insistent that you should have the vaccine, you’re well within your rights to ask why.

Better yet, find another doctor.

Read my article on how to minimise your risk of flu.

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