Healthy people who catch swine flu need not be given Tamiflu, the World Health Organisation (WHO) has announced. The advice appears to contradict the UK's policy of making the antiviral drug readily available to those who call the national pandemic helpline or approach their GPs.

Hundreds of thousands of doses have been given to British patients although the majority have not been severely ill. Fears have been voiced that mass use of Tamiflu will make the virus resistant to it.

The latest advice from the WHO said: "Worldwide, most patients infected with the pandemic virus continue to experience typical influenza symptoms and fully recover within a week, even without any form of medical treatment. Healthy patients with uncomplicated illness need not be treated with antivirals."

Previously the WHO had said antivirals should be given to patients with "serious progressive illness". The new guidance is the first time it has specifically advised against otherwise healthy individuals being given the drug.

The recommendation is based on the conclusion of an international panel of experts that includes representatives from the UK. The advice added that Tamiflu, also called oseltamivir, and the similar drug Relenza, also called zanamivir, should be given quickly to seriously ill or deteriorating patients.

The WHO guidance said at-risk groups should receive the drugs. "For patients with underlying medical conditions that increase the risk of more severe disease, WHO recommends treatment with either oseltamivir or zanamivir.

"These patients should also receive treatment as soon as possible after symptom onset, without waiting for the results of laboratory tests. As pregnant women are included among groups at increased risk, WHO recommends that they receive antiviral treatment as soon as possible after symptom onset."

Some medical researchers have expressed concern about the side-effects of Tamiflu, particularly sickness, nightmares and insomnia in children. A team from Oxford University said this month that children with mild symptoms should not be given Tamiflu and urged the Department of Health (DoH) to urgently rethink its policy.

Figures released by the DoH show that 45,986 courses of antivirals were given to patients in England in the week ending 18 August. In the previous week 90,363 courses of antivirals were given out. The data relates to people collecting the drugs after an assessment via the National Pandemic Flu Service. Many more have collected antivirals via their GP.

The DoH said the new WHO guidance was not too different from its own position that people with mild symptoms could recover without antiviral drugs.

The new WHO statement said: "Worldwide, around 40% of severe cases are now occurring in previously healthy children and adults, usually under the age of 50 years. Some of these patients experience a sudden and very rapid deterioration in their clinical condition, usually on day five or six following the onset of symptoms."

The first deaths of patients in Wales and Northern Ireland with swine flu has been announced, bringing the number of UK deaths to 61. In Wales, a 55-year-old woman was admitted to the Royal Gwent hospital in Newport on 2 August and given antiviral drugs. She developed cardiac problems and died on Saturday.

In Northern Ireland, a female patient who was said to have had an underlying health condition died last night in hospital. No further details were released.

The Department of Health has hinted that accumulating evidence about the degree of severity of the outbreak might lead to a change in policy. A spokesman said: "We believe a safety-first approach of offering antivirals, when required, to everyone remains a sensible and responsible way forward. However we will keep this policy under review as we learn more about the virus and its effects."

"The WHO recommendations are in fact in line with UK policy on antivirals. We have consistently said that many people with swine flu only get mild symptoms and they may find bed rest and over-the-counter flu remedies work for them.

"WHO state that 40% of severe cases worldwide have been in previously healthy children and adults and that serious cases should be treated immediately. This emphasises the need not to become complacent about the mildness of the illness and the reasoning behind a precautionary policy.

"People with underlying health conditions, pregnant women and parents with children under the age of one should speak to their GP if they have symptoms. If people have any doubts about taking antivirals they should contact their GP."