What is flu (Influenza)?

Flu (influenza) is a viral infection of the respiratory tract. In healthy individuals flu usually resolves without treatment within 1-2 weeks. It can cause significant health problems in people with pre-existing medical conditions such as asthma, COPD (chronic obstructive pulmonary disorder), diabetes and heart conditions.

The following is a summary about the disease. For further details speak to your local pharmacist or GP.


How is flu spread?

The flu virus spreads easily between person to person through droplets in the air when coughing and sneezing. Crowded, enclosed environments make it easier to catch. Flu can also be passed from touching surfaces or objects contaminated with the virus and then touching the nose or mouth.1

Flu in the UK and other countries

Seasonal flu occurs throughout the world. In the United Kingdom, most flu activity is from December till March. In the tropics, flu viruses can circulate throughout the year.

Up to date worldwide information on seasonal flu activity is available from the World Health Organization (WHO).1

Risk for travellers

For travellers visiting tropical and subtropical countries flu can be prevented by getting vaccinated.

Travellers can be at risk during the summer months, particularly if travelling in large groups that include tourists from other regions of the world where flu viruses are currently circulating. Crowded conditions increase the spread of infection e.g. Hajj or Umrah pilgrimages and cruise travel.1

What are the signs and symptoms of flu?

The time between coming into contact with the virus and before the symptoms show is between 1-3 days. The common symptoms are:

  • Loss of appetite
  • Fatigue
  • Headache
  • Fever
  • Nasal congestion
  • Sneezing
  • Muscle aches
  • Dry cough
  • Sore throat
  • Difficulty sleeping
  • Diarrhoea or stomach pain
  • Nausea and vomiting

Most symptoms typically last for 3-5 days but cough and tiredness may last for 1-2 weeks. People can be infective 5 days from the start of the illness, although children can remain infectious for 2 weeks.2

What are the complications of flu?

Complications of flu include:

  • Acute bronchitis
  • Pneumonia
  • Flare ups of asthma and COPD
  • Sinusitis
  • Febrile convulsions (seizures caused by high body temperature)
  • Heart failure

Risks of complications resulting in hospitalisation or even death are higher among:

    • Those aged  over 65 years
    • Very young children
    • People with certain risk factors (see section ‘when to consider the vaccination’)
    • Nursing home residents (due to age and enclosed living conditions)2

How is flu diagnosed and treated?

Flu is diagnosed from the symptoms; specific laboratory testing is rarely done. 1

Flu is usually self-limiting within 1-2 weeks and therefore antiviral medications are not recommended for people with flu who are otherwise healthy. The use of paracetamol and decongestants can help relieve the symptoms. Patients are encouraged to rest, keep well hydrated by drinking plent of fluids and increasing intake of vitamin C, vitamin D and Zinc whilst ill to boost their immune system. 3

What advice is there for those travelling to countries where flu is a high risk?

Travellers are advised to take the following precautions to reduce their risk of exposure to respiratory infections and prevent spreading them:

  • Limit close contact with people who already have flu
  • Minimise being in crowded conditions where possible
  • Frequent hand washing
  • Follow ‘cough hygiene’ – sneezing or coughing into a tissue and promptly discarding it safely and washing hands thoroughly
  • Avoid travel if unwell with flu-like symptoms1

Am I eligible to receive vaccination against flu on the NHS?

For the 2021/22 flu season, vaccinations may be offered at NHS expense if patients meet eligibility criteria.

You can check your eligibility by using Travel Jab’s smart tool by clicking here. Alternatively you can click here for detailed eligibility criteria.

If you are a healthy individual  who is not eligible for the free NHS flu vaccination then you may still wish to have the vaccination privately,  as doing so can reduce number of days off work and help prevent spread to other people.

What vaccinations are available against flu?

In the UK, flu vaccines are prepared in advance of the winter season. The vaccines  available are:

  • The live attenuated influenza vaccine (LAIV) (For children 2 to 17 years)
  • The Standard egg-grown quadrivalent influenza vaccine (QIVe) (For children 6 months to adults 64 years)
  • The cell-based quadrivalent influenza vaccine (QIVc) (For anyone over 2yrs)
  • The recombinant quadrivalent influenza vaccine (QIVr) (For anyone over 18yrs
  • The adjuvanted quadrivalent influenza vaccine (aQIV) (For adults over 65 years)

QIVc or QIVr is suitable for use in over 65 years age group if  aQIV is not available.

Following vaccination, protection is thought to last for approximately one year, although this may be less for the elderly. Therefore it is vital to get vaccinated every year.

Many vaccinations are grown in embroynated hen’s egg and therefore egg allergies should be mentioned to the pharmacist.4

You can click here for detailed information on recommended 2021/2022 influenza vaccines




This information is taken from trusted third party websites, NaTHNaC (Travel Health Pro) and EMIS (Patient info) and use of all information has been licenced under the Open Government Licence http://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/.

Although the materials are being used/replicated under the provisions of the Open Government Licence this in no way represents endorsement of Traveljab.co.uk by NaTHNaC, Emis, Public Health England, the NHS or the Department of Health and Social Care.

  1. Travel Health Pro: National Travel Health Network and Centre (NaTHNaC) https://travelhealthpro.org.uk/factsheet/51/seasonal-influenza
  2. Patient.Info: https://patient.info/doctor/influenza#nav-6
  3. NHS Choice Flu: https://www.nhs.uk/conditions/flu/
  4. The Greenbook: Influenza Chapter 19
  5. Department of Health: Seasonal Influenza Vaccination Programme 2018-19
  6. Public Health England: Influenza Patient Group Direction
  7. Public Health England: Annual National Flu Programme
  8. PSNC https://psnc.org.uk/wp-content/uploads/2018/08/PSNC-Briefing-043.18-Factsheet-Eligible-groups-for-the-national-flu-vaccination-service-2018-19.pdf
  9. https://cks.nice.org.uk/immunizations-seasonal-influenza#!topicsummary