@defenbaker
I'm unsure about the flu vaccine though... I don't normally have it as I rarely catch colds
Irrelevant - influenza and colds are caused by different viruses. Having said that, though, there is some evidence suggesting that having the flu vaccine makes you more susceptible to catching other (non-influenza) respiratory viruses. It's an open question at the moment whether that also applies to Covid-19.
(and am cynical as to its efficacy when there are 4(?) strains of flu but the jab only covers one)
Not true - see below, extracted from www.nhs.uk/conditions/vaccinations/how-flu-vaccine-works/
"There are 3 types of flu viruses:
Type A flu virus – this is usually the more serious type. The virus is most likely to mutate into a new version that people are not resistant to. The H1N1 (swine flu) strain is a type A virus, and flu pandemics in the past were type A viruses.
Type B flu virus – this generally causes a less severe illness and is responsible for smaller outbreaks. It mainly affects young children.
Type C flu virus – this usually causes a mild illness similar to the common cold.
Most years, 1 or 2 strains of type A flu circulate, as well as type B.
How the annual flu vaccine changes
In February each year, the World Health Organization (WHO) assesses the strains of flu virus that are most likely to be circulating in the northern hemisphere over the following winter.
Based on this assessment, WHO recommends which flu strains the vaccines should contain for the forthcoming winter.
Flu vaccines protect against 3 or 4 types of flu virus (usually 2 A types and 1 or 2 B types). Vaccine manufacturers produce flu vaccines based on WHO's recommendations."
Influenza viruses mutate rapidly, hence the need to change the vaccine every year. The evidence to date is that coronaviruses mutate much more slowly, so unlikely to have the same issue of needing to change the vaccine every year.