Image caption Typhoid fever is uncommon in England, with an estimated 350 cases occurring each year

More than 700,000 people recently immunised against typhoid may not have full protection because of a dud vaccine that has now been recalled, say experts.

Manufacturer Sanofi Pasteur MSD has recalled 88% of its stock - 16 batches - of Typhim Vi vaccine because tests found some samples were too weak.

Anyone immunised with the vaccine since January 2011 could be affected.

Officials stress that the vaccine was safe and posed no health threat.

But it could mean as many as 729,606 people who potentially received the affected vaccine are not fully immunised against typhoid, according to the body that regulates drugs in the UK, the Medicines and Healthcare products Regulatory Agency (MHRA).

Anyone who has been to a typhoid region of the world and has a fever, abdominal pain and vomiting should contact a healthcare professional A spokeswoman from the MHRA

Experts say people should not get revaccinated but should take precautions against typhoid when abroad.

If you received this vaccine and have recently returned from abroad, and are unwell, you should contact your doctor.

Precautions

Typhoid fever is uncommon in the UK, but people visiting South Asia and South East Asia, where the life-threatening bacterial disease is most common, are at greater risk.

Typhoid is very contagious. An infected person can pass the bacteria in their faeces.

If someone else eats food or drinks water that has been contaminated, they can catch typhoid fever.

It can be treated with antibiotics if diagnosed early enough.

The MHRA said: "There are no concerns over the safety of this vaccine, but the recall has taken place because the vaccine may not be as effective as it should be.

"Anyone who has been to a typhoid region of the world and has a fever, abdominal pain and vomiting should contact a healthcare professional. They can also give them information and advice about minimising the risk of getting typhoid."

Supplies of another injectable typhoid vaccine called Typherix, made by GlaxoSmithKline, are unaffected, as are those of an oral typhoid vaccine called Vivotif.

A spokesman for Sanofi Pasteur MSD said: "We are working hard to resolve the issue, but we cannot confirm an exact date when normal supplies will resume, although we hope this will be by the beginning of 2013.

"While 16 batches of vaccine are being recalled - 88% of the available stock in the UK - there are two batches in the supply chain that are unaffected and these will be distributed shortly."

A statement from the company said: "We understand the difficulties this recall may cause for our customers and people relying upon our vaccines. We would like to offer our most sincere apologies for the inconveniences incurred.

"The company is using all possible means at its disposal to address the matter and working to resume normal supplies of Typhim Vi® as quickly as possible."

A Department of Health spokeswoman said: "Vaccine is still available and we are working with vaccine manufacturers to help ensure that current supply problems are resolved as soon as possible.

"People who have recently been immunised, should seek medical advice about precautions to take whilst abroad to minimise the risk of infection, in case the vaccine has not provided full protection."