What follows is my personal experience and research. It should not be construed as medical advice.
Every winter brings another year I do not get the flu shot. I fear neither science or vaccines, but I am not sold on the efficacy of a preventative that is so often ineffective. Vaccine makers wrongly guessed the strain of flu in the 2017-2018 season. Business Insider reports the effectiveness rate is, at best, 10%.
The trouble with the vaccine annually is, we amateurs can guess, the amount of professional guesswork involved. TIME notes:
[E]xperts report that the flu vaccine, designed to inoculate hundreds of millions of people, may not be as effective as they’d hoped.
Normally in severe flu seasons like this one, the reasons for the suffering are pretty straightforward. Flu vaccines have long been manufactured in a decades-old process that involves growing the influenza virus in millions of chicken eggs, over a period of about four months. That means flu-shot manufacturers need a head start. Every year in the spring, influenza experts at the World Health Organization (WHO) make their best educated guess, based on the previous year’s flu cases, about which strains of the virus will make the rounds in the coming winter. Sometimes they nail it. But sometimes they don’t–and entirely different strains circulate that make people sick. [Emphasis mine.]
[T]he problem with flu is that the virus constantly changes. “It’s very diverse. Lots of different strains, and it’s changing all the time…So by the time we pick a version of the virus to make into a vaccine and put it into production, it might take six to eight months and in that time the virus might change.” If the vaccine isn’t a close match to the strain of the virus that’s actually circulating once fall and winter arrive, it won’t be as effective at stopping the illness.
Reporting on the 2016-2017 flu season, the September 2017 Journal of Family Medicine echoes Sabeti with a good news/bad news scenario on vaccine effectiveness:
The good news: Circulating viruses were a close match to those contained in the vaccine. The bad news: Vaccine effectiveness at preventing illness was estimated to be just 34% against A (H3N2) and 56% against influenza B viruses. There has been no analysis of the relative effectiveness of different vaccines and vaccine types.
The past 6 influenza seasons have revealed a pattern of lower vaccine effectiveness against A (H3N2) compared with effectiveness against A (H1N1) and influenza B viruses.
Even with professional guesswork and as many hits as misses, the near universal opinion of the medical community is, “Even if the flu shot doesn’t work, get it.”
“Get the partially-effective flu shot anyway” sounds more like business promotion for vaccine makers than health advice for potential flu sufferers.
While most people think of the flu virus as only being around during “flu season,” this isn’t true. The flu virus lives year-long, but goes about its grizzly business of infecting and killing people most effectively during periods of reduced solar radiation. Cannel, Veith, et al in Journal of Family Medicine (linked above) note an instance when “in early April, the predominant strain changed from A (H3N2) to influenza B.” The CDC says, “Seasonal flu viruses can be detected year-round.”
Fortunately, there is scientific evidence (and has been for some time) that consistent supplementation of Vitamin D is effective in combating not only the flu, but other respiratory infections. In a breakthrough study, British doctor and researcher, R. Edgar Hope-Simpson, surmised a link between flu outbreaks and seasons, noting the prevalence of flu outbreaks in shorter winter days. In the February 1981 Journal of Hygiene, Hope-Simpson says:
Outbreaks are globally ubiquitous and epidemic loci move smoothly to and fro across the surface of the earth almost every year in a sinuous curve that runs parallel with the midsummer curve of vertical solar radiation, but lags about six months behind it…Latitude alone broadly determines the timing of the epidemics in the annual cycle, a relationship that suggests a rather direct effect of some component of solar radiation acting positively or negatively upon the virus, the human host, or their interaction…The nature of the seasonal stimulus remains undiscovered. [footnote 4 in linked article]
In both hemispheres, in other words, influenza rates rise significantly for about two months on either side of the winter solstice. While Hope-Simpson recognized something natural acted “negatively upon the virus,” he could not identify it.
Hope-Simpson’s “seasonal stimulus” has been identified as Vitamin D, aka, “Bottled sunshine.” Reports The Independent in 2017:
Now a group of researchers has come up with a novel answer to the conundrum. The “seasonal stimulus” behind the annual winter flu epidemics is a lack of vitamin D due to shorter days and lack of sunlight.
Reports the Harvard Gazette on the global study involving 11,000 subjects,
“Most people understand that vitamin D is critical for bone and muscle health,” said Carlos Camargo of the Department of Emergency Medicine at Massachusetts General Hospital (MGH), the study’s senior author. “Our analysis has also found that it helps the body fight acute respiratory infection, which is responsible for millions of deaths globally each year.”
Similarly, the News (Australia) commenting on the same study:
Those who take the “sunshine vitamin” regularly cut their chances of respiratory infection by 12 per cent—the protection level offered by a flu vaccine.
(Sharif B. Mossad, writing for the Cleveland Clinic, explains the relationship between acute respiratory tract infection and influenza, noting the latter has differentiating characteristics.)
Easily obtainable in long late-Spring and Summer days, sunshine stimulates the body’s own production of Vitamin D. So, though the flu is a year-round virus, the natural formation of the vitamin in the summer fights off the virus. Cannell, Vieth, et al note:
In spite of people congregating on cruise ships, airplanes, nursing homes, factories, offices, subways, hospitals, etc., summertime outbreaks and the spread of influenza A are rare. [Emphasis mine.]
In other words, being around crowds of people is not specifically what spreads the flu. It’s lower levels of Vitamin D, owing to less sunshine, short wintry days, insufficient dietary Vitamin D intake, and lack of supplements that makes us susceptible. The conclusion of Martineau, Hooper, et al, in the British Medical Journal (February 2017) is simple:
Vitamin D supplementation was safe and it protected against acute respiratory tract infection overall.
Whether you should get a flu shot may be a question you must decide in consultation with your healthcare professional. Whatever your choice, Vitamin D supplementation is now a scientifically recognized means of preventing acute respiratory tract infections, including influenza. As such, it is a good idea to seek sunshine as often as you can in the winter months and consider getting your Vitamin D levels checked to determine how much supplemental Vitamin D you need.