(NaturalNews) The United Kingdom's Medicines and Healthcare Products Regulatory Agency (MHRA) has announced that a typhoid vaccine given to more than 700,000 people in the past two years was partially ineffective.
The vaccine in question, Sanofi Pasteur's Typhim Vi, is designed to prevent infection with the bacteria that causes typhoid fever. Although typhoid fever is rare in the United Kingdom and other first world countries, it remains endemic in many parts of the world, particularly southern Asia. Many health agencies recommended vaccination for anyone traveling to countries where the disease is prevalent.
Typhoid fever is transmitted through contact with the feces of an infected person and spreads most rapidly in areas with poor hand washing practices or water sanitation systems. Because it is a bacterial disease, it can be treated with antibiotics.
After tests revealed that many samples of the Sanofi Pasteur vaccine were too weak to convey full protection, the company recalled 88 percent of the remaining supplies from the market.
"We are working hard to resolve the issue, but we cannot confirm an exact date when normal supplies will resume," a company spokesperson said.
The MHRA warned that anyone who received the vaccine after December 2010 - as many as 729,606 people - could have received a dud batch. The agency emphasized that the ineffective vaccines did not carry any higher risk of adverse effects than the normal vaccine.
The MHRA also warned that people who may have received the dud vaccine should not get revaccinated. Instead, the MHRA advised that even those who had been vaccinated, see a doctor immediately if they begin to feel unwell after a trip to a typhoid endemic area. In addition, even people who have received the vaccine should take particular precautions against typhoid fever while traveling in such areas.
"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," the MHRA said. "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 minimizing the risk of getting typhoid."
An ineffective vaccine
The truth is; however, that even the full-strength vaccine is not nearly as effective as most patients may think. According to both the World Health Organization (WHO) and the Centers for Disease Control and Prevention (CDC), no form of typhoid immunization is 100 percent effective; indeed, the CDC reports that the average vaccine protects only between 50 and 80 percent of recipients.
The WHO notes that seven years after receiving the oral form of the vaccine, only 67 percent of people living in typhoid endemic countries are still protected, and that this figure may be even lower in travelers. The injectable vaccine protects 72 percent of patients after a year and a half, but by three years, this figure has dropped to 50 percent.
The organization further notes that the amount of time an individual patient is protected by the vaccine cannot be predicted with any accuracy, as it may vary due to both initial vaccine dose and subsequent exposure to the bacteria that causes the disease.
What all this means, of course, is that even people who have been vaccinated against typhoid fever must still take all the same precautions against infection as people who have not been vaccinated. In addition, even those who have been vaccinated should inform their doctors at once if they become ill after traveling in a typhoid endemic area - and this applies as much to patients who received the "full strength" vaccine as to those who received the "partially ineffective" one.