Less than half of Wandsworth residents in the influenza “at risk” category have taken up their free injection to protect them from the virus.

Health chiefs are launching an intensive campaign to increase the uptake of the flu jab amid fears that many vulnerable residents are unprotected.

Figures released by the Wandsworth Primary Care Trust (PCT) show that only 42 per cent of residents suffering from conditions such as diabetes, asthma or heart problems have had the jab.

Just last month diabetic Wandsworth teacher Jonathan Driver, 41, died following a severe bout of influenza. A postmortem examination found Mr Driver died from natural causes. However it is unclear whether the Emanuel history teacher had received a flu jab.

A PCT spokesman said: “Flu can be dangerous for certain groups of people, such as older people, those with heart problems, diabetes or asthma and those whose immune systems are suppressed by illness or treatment.

“It is really important for these vulnerable people to protect themselves by having the free flu jab.

“We are working with our GPs to encourage at risk patients to come to their surgery for the flu jab. We are offering patients extra flu jab clinics and home visits, particularly for those most at risk.”

The immunisation level among residents over the age of 65 was 68 per cent, one of the highest in the capital.

To find out about getting a flu jab talk to your GP, practice nurse or pharmacist, visit nhsdirect.nhs.uk or call NHS Direct on 0845 4647.