Q Do masks provide protection against swine flu?
A Yes, but probably not to the person wearing them. They help stop the virus being expelled from the mouth and nose when coughing or sneezing, but are much less effective at protecting the wearer from a virus picked up on the hands or circulating in the air. Wearing a mask thus becomes a public-spirited act.
Q Now swine flu has arrived in Britain how likely is it to spread?
A Highly likely – if it hasn't already. There were 14 suspected cases under investigation in Britain yesterday. It is a new virus, with a combination of genes from pigs, birds and humans, and has proved that it is easily transmitted from human to human. As it is a novel virus, immunity to it is likely to be low and almost anyone could be vulnerable.
Q Should Britain screen travellers at its borders?
A Flu is one of the most infectious illnesses known – one cough by an infected person can transmit the virus to a roomful of people. The disease takes up to seven days to produce symptoms so most travellers would not know they were infected until after they reached their destinations. Screening at airports and land borders may pick up some travellers but the effect would be limited. Politicians like to impose border controls because it shows they are doing something.
Q Will this outbreak develop into a pandemic?
A It has all the hallmarks of one and has already been identified on both sides of the Atlantic. Just how rapidly it is spreading will be confirmed in the coming days. What we don't know is how virulent the virus is. While some victims have died, others have recovered after only a mild bout of illness.
Q What defence do we have against swine flu?
A Better than we did against the last pandemics in 1957 and 1968. We have a stockpile of anti-viral drugs – Tamiflu and Relenza – which we did not have then. We also have a pandemic plan, drawn up by the Government since avian flu became a threat in 2003, which sets out what is to be done – from distributing the drugs and setting up helplines to closing schools and banning public events.
Q Has the pandemic plan ever been tested?
A Yes, in one of the biggest emergency planning exercises since the end of the Cold War that took place in 2007. It involved hundreds of health officials across the country.
Q Are there enough anti-viral drugs?
A Not according to the Tories. The Government says it has over 30 million courses of the drugs, enough for half the population. The Tories say this is not enough if family members of an infected person are to be treated prophylactically. In that case, enough drugs to cover three-quarters of the population will be necessary, they say.
Q How do anti-viral drugs work?
A Two anti-viral drugs have been licensed in Britain in the last decade: Tamiflu and Relenza. The problem with the flu virus is that it is constantly mutating, so a new vaccine has to be produced each year. The anti-viral drugs get round this by targeting not the virus itself but an enzyme that enables the virus to spread from cell to cell. Provided they are taken within 48 hours of the onset of symptoms they can shorten the illness and reduce its severity.
Q What is the difference between Tamiflu and Relenza?
A The big difference is that Tamiflu is taken as a pill while Relenza is inhaled directly into the lungs.
Q Why has the Government got both drugs in its stockpile?
A Because resistance has emerged in flu strains in some countries, rendering the drugs ineffective.
Q What about a vaccine?
A Pandemics tend to happen in waves separated by several months, so a vaccine could potentially be developed against the second or third wave, if they occur. A vaccine first has to be matched to the exact strain of the virus and then incubated in hen's eggs, which may take up to six months. Hundreds of millions of doses would be required which would put huge pressure on the world's laboratories.
Q Shouldn't a vaccine be the first priority?
A Previous vaccines against swine flu have turned out to be worse than the disease. An outbreak in the US in 1976 infected 200 people, of whom 12 were hospitalised and one died. But before it was over 40 million people had been vaccinated, 25 of whom died and 500 of whom developed Guillain-Barre syndrome, which can be fatal.