Have you had your flu vaccine yet? I got mine last week. A bit sore when the needle went in, but there was no swelling or lingering pain afterwards.
Those of us with chronic diseases or who are over 65 years of age are eligible for a free flu vaccine. And now is the time to get it – before the first wave of influenza strikes.
During the 2022 to 2023 flu season, more than 4,500 people aged 65 and older were diagnosed with the flu. Nearly 1,800 were hospitalised, 70 needed ICU treatment and 159 people died. Among older people, those aged 85 and older are more likely to be diagnosed with the flu and are more likely to be hospitalised.
Just because you have been vaccinated does not guarantee that you won’t contract the flu – the vaccine’s effectiveness varies with age. But you are likely to experience a less severe illness if you have been vaccinated.
Pan-European research shows that vaccine effectiveness was considerably lower in adults aged 65 years and older (34 per cent) compared with adults aged 18 to 64 years (51.6 per cent), with the highest effectiveness observed in children aged less than 18 years (57.7 per cent).
In response to the reduced effectiveness of the standard influenza vaccine, 10 European countries provide enhanced flu vaccines for free to some or all older people. A review carried out by the Health Information and Quality Authority (Hiqa) found that these enhanced flu vaccines are free only for certain groups, such as those aged 75 or older, or those living in care homes. The most common enhanced vaccines offered in European countries are high-dose vaccines, followed by adjuvanted vaccines. The use of adjuvants means the addition of non-viral material to the injection, which makes the immune system more likely to respond to the vaccine.
Hiqa’s recent health technology assessment (HTA) recommended that the Department of Health introduce adjuvanted vaccines for people aged over 65. While no major side effects were detected with the use of enhanced vaccines, some minor side effects – such as headache, pain at the injection site, or fever – were more common with a number of the enhanced vaccines, but these are usually mild and short-lived.
The term influenza originated in the Italian Renaissance when an outbreak of flu was thought to be due to the influence of a particular planetary alignment. There are three types of flu virus: influenza A, B and C, and within each type lies the potential for a myriad of subtypes.
All viruses are able to mutate. They alter their genetic make-up in response to changing environmental circumstances. Influenza virus is especially good at this, which explains why you can catch flu more than once and also why it is necessary to vaccinate people annually.
Flu virus invades the cells of the human body by injecting a spike of its own cell wall into the cells of the respiratory tract. It then begins to multiply, using the human cell as a new home.
The virus reaches the respiratory tract via droplets in the air, which come from the coughs and sneezes of other flu victims.
The H and N nomenclature used to identify particular subtypes of influenza A refers to proteins on the surface of the virus. One is called neuraminidase (N) and it enables the replicating influenza virus to break away from the cell it initially invaded and to spread throughout the body.
There are nine types of neuraminidase. The other is haemagglutinin (H), of which there are 12 basic types; it is the means by which the virus enters the cells of its host.
The most common flu virus in recent winters was influenza A of the H1N1 and H3N2 subtype.
Following Hiqa’s HTA, it seems likely that next year, the national flu vaccine programme for the over-65s will use an enhanced version of the jab.