GP surgeries across the country are having to postpone flu jabs for patients because of a shortage of vaccine. Crucell, the global pharmaceutical company based in the Netherlands, said it had stopped all supplies because of "an unexpected test result".
High-risk patients, including the elderly and those with chronic conditions such as asthma, may have to wait up to a month for their jabs, having been invited by GPs to have them before the winter flu season starts.
Flu lays low millions of Britons every winter, resulting in thousands of deaths, disruption to the NHS and harm to the economy.
It poses a particular threat to those in high-risk groups. Between 2,000 and 4,000 people, mostly elderly, die of flu-associated illnesses in a mild year – and up to 20,000 die in years when there is a severe epidemic.
Crucell supplies 10 per cent of the UK market for flu vaccine. The company said: "Patient safety is our first concern. We have voluntarily halted all deliveries because of an unexpected test result on one of our batches. We want to investigate the cause before we release the vaccine."
Another announcement will be made next Monday, when the results of further tests are known, it added.
The Department of Health said: "We are aware of some unexpected delays to one supplier's deliveries of the flu vaccine and advise GP practices to contact alternative suppliers if they are having problems."