The Flu Shot

Should you take the flu shot this year - 2019? That is the question that many parents, over 50s and other people with a number of health conditions are asking themselves. They have either been contacted by the health services or seen adverts on surgery walls and in hospitals or other healthcare settings.

Flu accounts for approximately 5% of deaths on an average winter. The vast majority of those people who die are over 65 years of age (1).

Vaccination is a contentious issue with views ranging from those who advocate mandatory vaccination to others who see vaccination as a dangerous procedure full of dangers that are kept from the public. As is normally the case with such fraught topics there is a lot more to this than is widely understood and the truth of the matter is often to be found somewhere in between the more extreme viewpoints.

The factors you should consider

Does the vaccination work?

A disease like measles has a vaccination success rate of 93% for one MMR shot, meaning that if you are directly exposed to the virus after having the MMR you have only 7% chance of developing symptoms. This figure is from the US health authority, CDC website (2). The flu shot has however a variable success rate, which is dependent on the strains of flu viruses in circulation each year. Again from the CDC website the effectiveness has ranged between 19% in 2014/15 to 60% in 2010/11 (3). So in a bad year such as 2014/15 had you been vaccinated and then exposed to the virus you would still have had an 81% chance of developing flu.

Note that many viruses such as measles have only one form to which the corresponding vaccine is well matched. In the case of the flu virus, which has many forms, the vaccine is changed each year, caters for 3-4 viruses and is rarely able to match those viruses perfectly. This is the reason for the flu vaccines poor success rate.

Can you trust the statistics?

While the public health statistics usually follow an accepted scientific method, the results that get quoted can be biased. In the case of flu statistics there have been some concerns that industry funded studies get into more prestigious journals and are cited more often than independently funded studies (4).

Are there better flu vaccines?

Recently a so-called quadrivalent flu vaccine which protects against 4 types of flu virus: A-types [H1N1, H3N2] and B types [Victoria, Yamagata] has been introduced. This has been theoretically examined in the context of ten years of Australian data from 2002-2012 and found to confer an improved level of protection. However this study was theoretical and frankly is probably not worth the paper it was written on (5). This vaccine is now available in the UK to all age groups apart from those over 65 years of age.

Data from the US however show a disappointing trend in the quadrivalent flu vaccine effectiveness over the past 4 years whereby the success rate has sunk consistently from 48% to 29% last year (2018/19). The US has used the quadrivalent flu vaccine since 2014 and so it is perhaps possible that the quadrivalent vaccine is losing its effectiveness already.

This is not surprising as flu strains mutate regularly making different types of vaccine less effective as time goes by. The quadrivalent vaccine uses some old strains and is probably past its use by date!

Does the flu jab protect against flu complications?

Flu by itself is normally a self-limiting disease that resolves after 1-2 weeks without complications. However some people are at increased risk of developing other more serious infections such as pneumonia, sinusitis and bronchitis after a bout of flu (6). In particular those over 65 and with other health issues are considered at greater risk of these complications. Given the potential for death or chronic ill health from these complications an important consideration is whether the flu vaccine actually protects against them. Currently there is no good evidence that the current vaccines protect against these more serious outcomes (7). However it could be argued that the risk of flu for the over 65s is reduced, and so the risk of complications is similarly reduced in those who have yet to catch the flu.

One fact to remember is that older people and also young children have less effective immune systems than adults aged between 18 to 65 years. As such the reported success rates of vaccines will be lower for this age group and this perhaps explains the poor success rate of around 5% reported by the recent review of old studies done by the independent Cochrane collaboration (7).

The dangers of flu vaccination

A known but uncommon danger of flu shots is Guillain-Barre syndrome. This is normally a rare autoimmune disease has a 7.4% mortality rate. It causes muscle weakness which may be permanent but usually resolves after a period of several weeks to years. The risk is 1 in 625,000 however, so I would personally discount it (8).

Anecdotally a number of people I’ve come across have suffered with colds, coughs or flu after the flu jab. The official line is that the vaccines cannot cause flu related illness as they contain inactivated viruses or at least viruses missing most of their genes. This could be the case, but it is also true, especially for some older people that a trip down the road to a health centre at peak colds and flu season will expose them to a number of viruses that they would not otherwise have come into contact with.

The anti-vaxxers

I have followed a number of prominent alternative health practitioners since I qualified in nutritional therapy 11 years ago and two of my most respected thought leaders have been very dubious about flu shots (John Briffa and Kris Kresser). Having gone through the evidence myself I’m not sure I’m entirely in agreement with them. This is despite my mistrust of the health authorities on many issues, which in my view is well founded.

Who needs the flu jab the most?

My view is that the flu vaccine is pretty safe, but that there is not an insignificant risk, especially for the elderly in going out to a busy doctors’ surgery in peak colds and flu season to get it.

For the rest of the population there is a case for vaccinating them, even if the risk of serious illness is very low, which it is in all but serious pandemic years. The most important groups to vaccinate to reduce the risk of serious illness in the elderly include children, workers in the education and especially the health sectors. Thus flu vaccination in reality is all about helping others, not about reducing the risk to you.

Whether the elderly, those who need to avoid flu the most actually need the jab is in my view a debateable point. I would actually look each season at the success rate of last years’ vaccine (remember this is not for the elderly specifically, but for the whole population). For instance I’ve seen a figure of 47% quoted for last seasons’ flu vaccine. Because I don’t entirely trust the figures provided by the health authorities I would see this as guidance only. The elderly would then have a much lower percentage applicable to their cohort, perhaps as low as 10%.

I would then ask myself about the current prevalence in the local population of the virus. If it was high your elderly parents may be better off staying at home rather than risking going out to a place where many ill people go for a jab that may only have a 1 in 10 chance of protecting them if they come into contact with the virus. If you think about it makes far more sense for the elderly to avoid carriers and “super spreaders” such as young children and health workers rather than risk infection with any number of illnesses in peak cold and flu season (Oct – Feb).

On the other hand if there was a pandemic such as the Spanish flu pandemic of 1918 when millions died a vaccination could be considered more important for everyone as the risk of death would be much higher for all age groups. This would still however depend on efficacy of the vaccine in different age groups. For instance in 1918 it was the young adults who were most prone to the virus, so they would have been the most important target for vaccination.

References

  1. http://vk.ovg.ox.ac.uk/vk/influenza-flu Flu deaths in the UK.
  2. https://www.cdc.gov/vaccines/vpd/mmr/public/index.html MMR vaccine efficacy.
  3. https://www.cdc.gov/flu/vaccines-work/effectiveness-studies.htm Flu seasonal efficacy.
  4. https://www.ncbi.nlm.nih.gov/pubmed/20614424 Studies bias.
  5. https://bmcpublichealth.biomedcentral.com/articles/10.1186/s12889-016-3297-1 The quadrivalent vaccine.
  6. https://www.webmd.com/cold-and-flu/flu-complications#1 Flu complications.
  7. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6491101/ Evidence of complications.
  8. https://www.ncbi.nlm.nih.gov/pubmed/20614424 Dangers of flu shots.