Pandemic influenza - key facts
What is pandemic influenza?
18. Influenza is a familiar infection in the UK, especially during the winter months. The illness, caused by an influenza virus, can be mild or severe and can lead to death.
19. Pandemic influenza is different from ordinary influenza because it occurs when a new influenza virus emerges into the human population and spreads easily from person to person. It may be that some groups of people are likely to be more susceptible than other groups, especially older people and those with certain health conditions, such as heart or chest disease. Observing good practice on personal hygiene is important to help reduce the spread of the virus (see paragraph 108 entitled 'Infection control and personal hygiene').
20. As it will be a new virus, it is likely that the entire population will be susceptible, because no one will have any immunity to it. Therefore, it may attack healthy adults as well as older people and other potentially vulnerable groups. The lack of immunity in the population will mean that the virus has the potential to spread very quickly between people. This will result in many more people becoming severely ill, with additional pressure on care services.
21. The circumstances exist now for a new virus to emerge and spread worldwide.
Although a pandemic has not yet started, experts warn that it could begin soon.
Signs and symptoms of influenza
Most significant
- Fever
- Headache
- Cough or shortness of breath
- Malaise (general bodily discomfort/feeling of unease)
- Sudden onset of illness
- Chills
Other symptoms
- Aching muscles
- Sore throat
- Runny nose, sneezing
- Loss of appetite
Incubation period (the time from exposure to first symptoms)
22. For most people, the range is from one to four days (but typically two to three). Without intervention - or significant immunity in the population - historical evidence suggests that one person infects about two others on average and that influenza spreads particularly rapidly in communities such as schools or care homes.
Infectious period (how long you are infectious to others)
23. People are most infectious to others soon after they develop symptoms, though they can continue to shed (excreting or casting off the virus through their secretions) virus for usually up to 5 days after the onset of symptoms. (This extends to 7 days in children)
24. It is sometimes stated that patients are infectious shortly before they develop symptoms; however, the evidence for this is limited. Spread from a person before they develop symptoms has rarely been recorded, though experimental studies have shown that some people start shedding low doses of virus in the 24 hours before symptoms occur. Some people can be infected without showing symptoms and, as they may shed the virus, be able to pass on the infection.
How is pandemic influenza caught and spread to others?
25. Pandemic influenza is spread from person to person by close contact. Please refer to the section called 'Infectivity and mode of spread' for more details, at paragraph 83. Here are a few examples of how this infection can be spread:
- infected individuals can pass the virus to others through large droplets when coughing, sneezing and even talking within a close distance (usually three feet or less).
- you can pass on the virus by direct contact with an infected individual. Shaking or holding hands with an infected individual followed by touching your own mouth, eyes or nose without first washing your hands with soap and warm water will also allow the virus to spread to you.
- you can spread the influenza virus when environmental and inanimate objects, such as door handles and light switches, become contaminated with the virus. Once again, if a person touches these objects and then touches their mouth, eyes or nose without first washing their hands with soap and warm water, their chances of catching the virus are increased.
Key messages to the public (including community care and health workers)
26. The key messages to those who have flu-like symptoms are:
- stay at home
- don't spread it around
- telephone the national flu line
Training and education
27. Ensuring good hygiene and infection control practices are an essential part of what we must all do in response to an influenza pandemic. However, improving hygiene benefits individuals and services more widely. We need to get the lessons about hygiene ingrained in the population as a whole and, in particular, the health and community care workforce. To leave training of the workforce until a pandemic occurs is irresponsible. In any event, good hygiene will limit the spread of a number of infectious diseases, including seasonal influenza and antibiotic-resistant infections. Local authorities and their health colleagues should consider establishing regular training programmes in good hygiene to remind both existing and new staff of its importance.