HEALTH MATTERS: NHS Highland's Dr Tim Allison on why becoming vaccinated against Covid and flu is an act that helps not just the individual but the whole community
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We talk about vaccination and about immunisation. They are two words that mean pretty much the same thing, but they also tell us about important ways to protect our health.
Vaccination means giving a vaccine and it started with the prevention of smallpox. Smallpox is now a disease consigned to history, but until recently it was a terrible threat. Smallpox was frequently fatal and when it did not kill it left scars that lasted a lifetime.
It was most likely the virus that almost wiped out the population of St Kilda.
However, a vaccine was developed. This built on experience from other countries and from observation of people who were infected with cowpox.
Cowpox is like smallpox, but is much less severe, and people who caught cowpox from milking cattle did not suffer from smallpox.
Smallpox has now been eradicated from the world thanks both to the vaccine and other public health measures such as contact tracing and isolation.
It is easy to forget that diseases such as smallpox, diphtheria, measles, polio, tetanus and many others were once killers of children and adults. Vaccination has transformed the health of the population and made life far healthier.
Immunisation means the development of immunity through getting a vaccine. Immunity is the protection that our own bodies generate to guard us against infection.
We can get immunity following an infection, but if immunity is possible before getting an infection then the risks that go with infection are avoided. This is what vaccines do by stimulating our own immune system.
There are different ways in which vaccines can work, but in general they cause the body to react as if it were being infected while not having the infection. Vaccines may imitate a harmless part of an infectious organism and cause the build up of defence against the organism.
Some vaccines can give us immunity that lasts for many years. However, the body’s immune response may decline over time and a booster vaccine may be needed to increase the immunity to new infection.
Vaccines are designed to target parts of the infecting organism and so if the organism changes and the part that is being targeted changes, the vaccine will be less effective. That is the case with influenza or flu, where the flu virus keeps changing and so the annual vaccine also keeps changing to give the best defence every year.
Over the next few months many people will be offered vaccines for several different reasons.
Since immunity against flu has decreased, it is vital for people to take up the offer of flu vaccination. People who have not had a vaccine against Covid, such as young people aged 12-15, have the opportunity to protect themselves and improve population immunity by taking up the vaccine. Those who have already been vaccinated will benefit from a booster for their immunity too.
Vaccination stimulates our own bodies to generate immunity to infection and our own individual immunity helps tackle infection not just for ourselves but for the whole community.
• Dr Tim Allison is director of public health and policy at NHS Highland.