Health experts have moved to reassure the public after a patient diagnosed with a Sars-like virus died in a hospital in Birmingham.

He was one of three members of the same family who have caught the virus, apparently by human to human transmission. Of the 12 people known to have been infected with the virus globally, half have died. The coronavirus responsible is distantly related to the one that gave rise to Sars (Severe Acute Respiratory Syndrome), which caused global panic and hundreds of deaths a decade ago.

But – critically – it lacks Sars’ ability to spread easily among populations, experts said. So far human-to-human transmission has only been observed among close family contacts and the virus has not spread into the wider community.

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The patient who died on Monday was being treated as an outpatient at Queen Elizabeth hospital, Birmingham for an unrelated condition which made him more susceptible to respiratory infections, the Health Protection Agency said.

He is believed to have caught the virus from his father who had recently travelled to Saudi Arabia and Pakistan. The father remains severely ill in hospital in Manchester, where he was transferred for treatment on an ECMO machine, which oxygenates the blood when the lungs fail.

A third member of the same family who was also infected with the virus, developed a mild flu-like illness and has since recovered, without needing admission to hospital.

An earlier, unrelated case was diagnosed last September in a patient who had flown to London for treatment after falling ill in Qatar. He remains seriously ill, the HPA said.