What is a Pandemic, and how serious might it be?


A pandemic is a global outbreak or epidemic. In the case of flu viruses, pandemics typically appear about three times in every century when a strain emerges against which humans have no immunity.

In recent times unfortunately we have become used to thinking of flu as being a minor illness. Much more serious infections are possible however - as with human cases of H5N1 that have recently occurred and with the 1918-19 pandemic strain.

The biggest human pandemic in the 20th Century occurred in 1918-19 resulting in approximately 50 million deaths worldwide.

Although a mutation from H5N1 Avian flu seemed for several years to be the most likely source of a pandemic flu virus, experts remained concerned that a pandemic virus might yet emerge from an entirely different source, making careful surveillance of flu viruses a global imperative. This is what has ultimately happened with H1N1 Swine flu.



What is Swine flu?

Flu occurs in many animal species as well as in humans, such as horses, pigs and birds, but flu strains normally circulate only among members of their habitual host species. Occasionally a new strain emerges that is capable of making the leap from one species to another. This has now happened with swine flu: the new strain appears to have "hybrid" characteristics of pig, avian and human flu, with the added ability of now being able to circulate easily between humans.



How is it spread?

It spreads in exactly the same way as "normal" seasonal flu - by inhalation and via contaminated objects (for example, by touching them and then bringing your hand to your mouth).



How serious is it?

We don't fully know. The initial cases in Mexico appeared to have a much higher fatality rate than ordinary seasonal flu, with young adults more seriously affected than the usual risk groups for seasonal flu, such as the elderly. The cases that have spread beyond Mexico so far seem rather milder, but it is still too soon for a true picture of things to be clear.



What precautions can you take?

The good news is that antiviral drugs are known to be effective and can be used both for treatment and for prevention in appropriate circumstances. These are not vaccines, but come as capsules (Tamiflu) or an inhaler (Relenza). There is no reason for people to take these at the moment, unless they actually have symptoms or are at special risk of exposure. If the new strain begins to circulate in the UK, first-line precautions include frequent hand washing, possibly face masks, and minimising contact with people who are unwell.



Is it worth getting a seasonal flu jab?

There are only limited vaccine stocks now available, so this may be quite difficult, and it is not known whether the current seasonal flu vaccine offers worthwhile cross protection. At least one of the US cases occurred in a person known to have received this year's vaccine, but we can't yet know if he had a milder illness as a result.



What are the early symptoms of swine flu?

Fever, malaise, respiratory difficulties, and all the symptoms of "normal" flu.



What should you do if you have any symptoms?

If you are unwell with symptoms of flu, report them to your GP or to NHS Direct (Tel: 0845 46 47), and stay at home.



Is it safe to travel?

Mathematical modelling suggests that restricting travel would make no significant difference to the international spread of flu viruses; and if the virus continues to spread, the risk of infection will probably be the same in the UK as it is in most of the other countries that have so far received cases.

Follow advice from the Foreign & Commonwealth Office, the Department of Health, and other key sources, very closely.



If you consider that you may be occupational at specially increased risk (e.g. medical/healthcare workers, news industry etc), take special advice regarding travel with antiviral medication, facemasks and alcohol hand gel, and other personal protective measures.