This year I have missed the first boat and have to wait for supplies of the vaccine to be replenished in November. There are now problems with supply meaning that promises for widespread vaccination, like so many other political targets, are falling short.
There has been an unusual rush for many people to get vaccinated before the flu season piggy backs on the pandemic’s winter return, so we have run out of stocks for the moment – just as the flu season approaches…..
That is, if it does. Part of my causal approach was encouraged by news that the flu season in the southern hemisphere has not really happened, mainly due to collective changes in behaviour, and partly due to increased uptake of the vaccine on the back of the COVID pandemic.
From Australia and NZ, across to South Africa and then Chile and Argentina, the flu season has not taken off at all. The table below from “Science” via the Bart’s blog shows the documented cases of flu falling off a cliff:
Relaxing ones approach to flu in the northern hemisphere on the back of this might be a mistake, as things are very different up here and the virus can easily mutate between their winter and ours. Time will tell, but the experience ‘down’ there has been unusual.
Why might this be?
Clearly change in behaviour must be a big driver of this, as well as increased uptake of flu vaccines, though availability does vary across many of the countries showing a drop. So reduced exposure really makes a big difference to the rate of flu infections, and so by implication, COVID19 too. This supports the use of social distancing, mask wearing and hand washing. They seems to have a dramatic effect down south.
But might the flu jab have a direct effect on immunity itself?
A study from Brazil back in June showed reduced risk of complications in those who had recent flu jabs with an 18% reduction of the risk of needing intensive care and a 17% reduced risk of death. Another from Italy noted the association too. Dutch healthcare staff given the vaccine had lower rates of illness than those who don’t too and in the US it is suggested that a 10% increase in flu vaccination is associated with a 28% reduction in COVID19 mortality.
“Every year, influenza causes 290,000 to 650,000 deaths worldwide and vaccination is encouraged to prevent infection in high-risk individuals. Interestingly, cross-protective effects of vaccination against heterologous (different) infections have been reported, and long-term boosting of innate immunity (also termed trained immunity) has been proposed as the underlying mechanism.
Several epidemiological studies also suggested cross-protection between influenza vaccination and COVID-19 during the current pandemic. However, the mechanism behind such an effect is unknown. Using an established in-vitro model (laboratory) of trained immunity, we demonstrate that the quadrivalent inactivated influenza vaccine used in the Netherlands in the 2019-2020 influenza season can induce a trained immunity response, including an improvement of cytokine responses after stimulation of human immune cells with SARS-CoV-2.
In addition, we found that SARS-CoV-2 infection was less common among Dutch hospital employees who had received influenza vaccination during the 2019/2020 winter season (RR = 0.61 (95% CI, 0.4585 – 0.8195, P = 0.001).
In conclusion, a quadrivalent inactivated influenza vaccine can induce trained immunity responses against SARS-CoV-2, which may result in relative protection against COVID-19. These data, coupled with similar recent independent reports, argue for a beneficial effect of influenza vaccination against influenza as well as COVID-19, and suggests its effective deployment in the 2020-2021 influenza season to protect against both infections.”
The interesting thing about this is the finding of cross-reactivity between the virus and other infections. The popular myth is that immunisations can “overload” the immune system, but this evidence supports the opposite; it enhances it.
As ever there is the alternative view, with this paper suggesting just the opposite. However, this is a less detailed statistical analysis with many unknowns, in particular which vaccine is used and how they are offered to the population. The bulk of the evidence suggests a benefit. despite expecting people vaccinated to have a higher risk of COVID as they are naturally a higher risk population.
However, I’m convinced by the evidence of reduced problems in those vaccinated. The next thing is trying to get one!