London: A jab to control high blood pressure has been invented by British scientists.

A third of all adults suffer from high blood pressure which increases the risk of heart disease and stroke.

Now Cheshire-based Protherics has created a vaccine, based on a protein found in limpets, which would require patients to have a three-jab course with a booster every six months.

The jab which has already been trialed successfully on humans is is a viable alternative to the current treatment where pills are given. The limpet protein in the new jab attacks a hormone called angiotensin which raises blood pressure by narrowing arteries.

Protherics is planning trials of an improved version of the jab, which is ten times more effective at stimulating the immune system than its original formula.

People who have tried it have suffered few side-effects, although one in ten did complain of a brief, flu-like illness.

A successful jab would guarantee its manufacturers a healthy share of the $24bn (£12bn)spent around the world annually on blood pressure medicines.

Ideally, patients would be given an initial course of three injections, with a week or fortnight between each jab. A booster shot every six months, or even once a year, would keep blood pressure low. The jabs will be offered privately rather than on the UK’s NHS public health service.

Another company, the Swiss firm Cytos Biotechnology is developing a similar vaccine using an empty virus shell to spur the immune system into action.

Zurich-based Cytos, which is also developing anti-smoking, obesity and flu vaccines, has already shown that its jab is effective at lowering blood pressure.

But the reduction was less than that achieved by tablets already available on prescription. Further trials are due to later this year.

In time, the vaccine may be given to ward off problems in young men and women with a family history of heart disease.

Various blood pressure tablets already on the market work by targeting angiotensin, either by cutting production of the hormone or by stopping it from working properly. But many people stop taking the daily tablets simply because there are no obvious signs that they are boosting their health.

Others give up after suffering side effects. Beta blockers, a major type of blood pressure pill, can cause fatigue, cold hands and feet, nausea, diarrhoea and impotence. They have also been linked to the risk of stroke.