Civil Resilience

Infectious disease outbreaks

How infections spread, who is most at risk, the hand washing and vaccination habits that protect a household, and the pandemic the government plans against.

  • Health

What it is

Infectious diseases are caused by microorganisms such as bacteria, viruses, parasites or fungi. Be Ready says they spread from person to person directly, by physical contact or droplets in the air, or indirectly, for example when an infected person touches a door handle that someone else then touches. Zoonotic diseases spread from animals to humans, directly or indirectly; see animal and plant health.

Anyone can be infected, but some people are more likely to catch an infection or to become seriously ill. The groups vary by disease but may include people with a weakened immune system or other underlying conditions, older adults, babies and young children, and pregnant people.

What it does to a home

An outbreak changes routines rather than the building. Hand washing, covering coughs, cleaning touched surfaces and letting fresh air in are the measures Be Ready lists. Someone who is unwell should stay at home or keep away from others, and some diseases carry specific exclusion periods, which the NHS publishes by condition. Vaccination is described as the most effective way to prevent many infectious diseases, although not every disease has a vaccine.

Who warns you

The UK Health Security Agency, which the National Risk Register describes as having well-tested capabilities with NHS responders to detect, contain and treat novel infectious diseases, and the NHS. The NHS website explains how vaccines work and their common side effects, lists the routine vaccinations and when they are given, and carries travel vaccination advice. TravelHealthPro covers health risks abroad. The e-Bug website, run by UKHSA, has free resources for parents to teach children about hygiene.

How the government assesses it

The National Risk Register 2025 carries two risks. A pandemic is usually a novel pathogen spreading quickly because the population has no immunity, and experts consider a respiratory pathogen the most likely cause. The reasonable worst case is an unmitigated respiratory pandemic in which 50 per cent of the UK population falls ill over its course, about 1.34 million people need hospital treatment and up to 840,000 die, with the emergency stage lasting at least nine months and possibly coming in several waves. The government also plans across five transmission routes, respiratory, blood and sexual, touch, oral through food and water, and vectors such as mosquitoes, covering known and unknown pathogens.

The second risk is an outbreak of an emerging infectious disease, such as the high consequence infectious diseases Ebola and Middle East Respiratory Syndrome. Its reasonable worst case is a novel respiratory virus emerging from animals abroad, with a small number of cases imported before border measures apply, up to 2,000 UK cases and up to 200,000 contacts to trace. The register also notes that antimicrobial resistance could make a pandemic deadlier through secondary bacterial infections; see antimicrobial resistance.

Where to look

Before

  • Keep you and your family up to date with routine vaccines. The NHS lists which are offered and when.
  • Learn to wash hands properly. The NHS has pictures and videos on the best way.
  • Before travelling outside the UK, check TravelHealthPro and the NHS travel vaccination guidance, and get vaccinated if needed.
  • Use the e-Bug resources from UKHSA to teach children hand and respiratory hygiene.

During

  • Wash hands with soap and running water for at least 20 seconds, before and after handling food, after the toilet or a nappy change, after contact with animals, after coughing or sneezing, and when unwell or around people who are.
  • Use hand sanitiser only when soap and water are not available. It does not remove every organism, for example norovirus.
  • Cover coughs and sneezes with a tissue and bin it.
  • Clean surfaces people touch a lot, such as door handles, and disinfect areas in contact with food, dirt or body fluids.
  • Let fresh air into occupied rooms.
  • If you are unwell, stay home or avoid contact with other people.

After

  • Follow the exclusion period for the disease on nhs.uk before returning to school or work.
  • Check again that routine vaccinations are up to date.
  • The National Risk Register says recovery from one wave of a pandemic can be hampered by the arrival of the next.

Related pages

Sources

Last updated 29 October 2026. Reviewed 29 October 2026