The flu vaccination (or flu jab) helps to protect against viruses that can cause flu symptoms.

It is provided each year on the NHS, and those who are at increased risk of flu or more likely to develop complications are advised to have it (however, it can be helpful in presenting flu in everyone, not just these groups).

As we’ll also discuss, many people who are at increased risk or have an underlying illness are eligible to have the vaccination for free.

How common is flu?

Influenza is very common and it’s difficult to quantify how many people will develop the illness in the UK, over the course of any given year.

Nearly everyone will get the flu at least once over the course of their lives. Many people will develop it multiple times.

Flu can be caused by several different viral strains, so the prevalence of flu can vary from year to year (depending on the prevalence of the viruses responsible). It’s therefore difficult to predict how many people are likely to be affected annually.

Statistics on GP visits for flu-like illnesses are published by Public Health England. According to data for the year 2016-17, the weekly GP consultation rate for influenza-like illness (or ILI) rose above the baseline threshold (of 14.3 per 100,000) in December and remained there for 6 weeks. The rate peaked at 20.3 per 100,000 in January.

In the year 2014-15, it was above the threshold for over twice as long (14 weeks).

However, many people with flu may not necessarily see their doctor (or need to). In the majority of cases the symptoms are very easy to identify and can be treated at home, by resting and staying hydrated (although those at risk of developing complications are advised to see their GP).

So, in reality, the number of actual flu cases is very probably much higher than the number stated above.

Who should get vaccinated?

The flu jab can be helpful in preventing flu in everyone.

However, it is recommended in people who are either at increased risk of contracting flu, or are medically more likely to develop complications as a result of flu.

For instance, persons who work in frontline health services, such as:

  • nurses
  • care workers
  • doctors
  • hospital staff
  • and GP surgery staff

will be advised to have the flu jab, because they deal with patients on a regular basis. The flu jab helps to prevent health and social care workers from developing flu, and helps to prevent them from passing the virus onto patients.

Those who act as the primary carer for an elderly or disabled person, and persons living in a long-term care residence are also advised to have it.

A person may be more susceptible to developing complications from flu, and therefore be advised to have the vaccine, if they are:

  • over 65;
  • pregnant;
  • overweight with a BMI of 40 or higher;

or if they are living with a long-term medical condition, such as:

  • a respiratory illness, such as asthma, COPD or bronchitis
  • diabetes
  • sickle cell disease or problems affecting the spleen
  • a condition affecting the immune system, such as HIV (persons living with someone who has a weakened immune system may also be advised to have a flu jab)
  • heart disease
  • liver disease
  • kidney disease
  • Parkinson’s, motor neurone disease or multiple sclerosis
  • or a condition which involves taking immunosuppressant medication (such as steroids), or having immunosuppressant therapy (such as chemotherapy).

Those with other illnesses not mentioned above may also be recommended the flu jab; particularly if their condition could be exacerbated by the flu (or vice versa). A doctor will assess a patient’s individual risk and offer the vaccination where appropriate.

Who can get it for free?

The flu jab is free on the NHS for persons who are:

  • aged 65 or over (or are currently 64 but turns 65 by the end of March the following year)
  • pregnant
  • living in long-term care residence
  • the primary carer for an elderly or disabled person
  • at increased risk of contracting flu or developing complications due to an underlying condition (see above).

If you have a long-term illness not mentioned in the section above, you may still be able to get the vaccine for free. Ask your GP for more information.

The flu vaccine is also available free of charge for children under 3, or children aged between 2 and 17 with a long-term medical condition (the vaccine nasal spray is typically given to 2-17 year olds).

Front-line health and care workers are eligible to have their vaccination paid for and arranged by their employer.

How it works

Essentially, vaccines work by imitating an infection on a much smaller scale. They contain a small amount of a synthetically-altered (or ‘killed’) version of the virus, or pathogen, they are designed to prevent. When a vaccine is injected into the body, the virus doesn’t cause an infection to develop. But it does trigger the immune system into developing antibodies against the pathogen. These antibodies can up to around two weeks to get up to full strength.

Following vaccination, when the body encounters the pathogen again, the immune system is then able to recognise it, and generates the antibodies required to fight the virus.

How often should I have it?

The flu vaccine changes every year, because the viral strains that cause flu adapt and mutate over time. People who need the flu jab will therefore be advised to have it every year.

Every February, the World Health Organisation (WHO) evaluate which strains they think will be most prevalent in the winter months to follow. They then advise makers which strains these vaccines should protect against, and these vaccinations then go into production, before being made widely available in September.

How effective is it?

The vaccination is the best option available for those at risk of flu or related complications, and research has shown it to be effective in preventing flu.

But flu is, of course, unpredictable; so how effective vaccinations are will vary from year to year. Research published by the US Center for Disease Control and Prevention (CDC) states that effectiveness estimates mostly tend to range between 40% and 60%.

The NHS advises that, while the flu vaccine is not 100% certain to stop someone from catching flu, even in those cases where someone contracts it following vaccination, they are more likely to have less severe symptoms and recover quickly (because their immune system will be better able to deal with the infection).

So even where the vaccination doesn’t prevent flu, it can still significantly help to fight the infection off.

Can it cause side effects?

As is the case when having any vaccination injected into the arm, it’s not uncommon to experience discomfort and aching in the arm for a few hours afterwards. Some people may also develop aches and a mild fever one or two days later, but these are likely to pass after a short time.

It’s possible, but very rare, to develop severe side effects or an allergic reaction after having the flu jab. If you notice anything unusual after having it, speak to your doctor.

Some flu jabs contain egg; so if you have an allergy to egg you will need to let your doctor and the person administering the vaccination know.

How to go about getting it

If you are at increased risk of flu or have a long-term illness, you should speak to your doctor about having the flu vaccine. Some pharmacies are also to offer and administer it.

October is the ideal time to have the flu vaccine, but it can still be administered later than this and be effective.