The flu jab . . . an autumnal routine

As the autumn rolls in, it’s time once again for the annual flu jab, if you’re part of the population for whom such a preventative strategy is deemed cost-effective by the UK’s Joint Committee on Vaccination and Immunisation (JCVI). That is, children aged 2 and 3, and those in school up to Year 5, adults whose health is otherwise compromised, and those over 65. Notes for this diary entry were collected from The Guardian’s ‘The Long Read: The Endless Quest for a Perfect Flu Vaccine,” from the Wall Street Journal’s ‘The Making of a Flu Vaccine,’ from the UK government’s press release on the new enhanced vaccine, and from Oxford University’s Vaccine Knowledge Project.

Flu is such a tricky virus; it mutates constantly, and a new virulent mutation is always feared. The World Health Organisation (WHO) monitors influenza cases worldwide, and looks at the incidence of cases old and new, as it tries to determine, some six months ahead of time, what types of flu are likely to be pervasive in north or south hemispheres. This year as in 2018, WHO has identified three, or four strains of influenza as prime targets. Having identified these strains, the laboratory machinery is rolled out to produce the vaccines (live virus is grown in chicken eggs or cell culture, for example, before ‘inactivation’ (effectively killing the virus) or ‘attenuation,’ (rendering the virus incapable of reproducing itself).

The JVCI here in the UK has adopted a strategy of using different sorts of influenza vaccines for different age groups. Thus, according to Oxford’s VKP notes, a quadrivalent cocktail of four inactivated virus particles is available for children of 6 months to 2 years of age (not a free target group with the NHS) while children of 2 and 3 years, as well as those in Primary School up to Year 5 will receive a free nasal spray of live, attenuated flu vaccine with the same four target influenzas. Not offered free on the NHS to healthy folks aged 18-65 is the quadrivalent, inactivated vaccine: numerous studies have shown that in this age-group, the benefits of the predictive vaccine in terms of later infection and illness are not cost-effective, since not enough illnesses are prevented (the efficacy in this age group is on the order of 1 influenza case vs 2 cases if un-immunised, out of 100 individuals). Certain at-risk target groups (eg those with a long-term health condition, pregnant women, carers) will receive this vaccine free on the NHS, however. A trivalent, three-virus vaccine along with adjuvant properties (components that stimulate the immune system, especially in older folks), which JVCI hopes will help prevent deaths from the infection, is offered free to those over the age of 65. The government’s own Press Release describes more comprehensively who will receive the free jabs.

But will it work? If the WHO has identified the targets successfully, then many deaths are likely to be prevented, as vulnerable people will be much less likely to succumb to those particular influenza strains. If the ‘wrong’ virus is spreading throughout the UK, then the vaccine won’t do much good, though this year the adjuvant effects of the enhanced version are likely to help the immune response of older folks. Older folks, having the ‘experience’ of many years of flu outbreaks, are likely to be primed already to many influenzas, but their immune systems could do with a bit of stimulation!

Older folks may not appreciate that the immunisation of young children, according to an extensive study in Japan, actually helps to prevent deaths among the older generation, since the chances of grandparents catching their beloveds’ infection are reduced.

Everyone hopes, one day, that a ‘universal influenza vaccine’ may be developed which will prime our bodies against all incoming flu viruses. But until then, it makes sense to take advantage of the best guesses and strategies for public health, and get the jab if you’re a target cohort.

And we are, having received an invitation for an inoculation, so we hied ourselves off to the Health Centre yesterday afternoon for our annual jabs. Scarcely felt a thing!

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