Clinical trial takes steps towards first paratyphoid vaccine

A UK study has shown that a vaccine can protect people against paratyphoid fever.

Paratyphoid fever affects over two million people globally each year. Yet no licensed vaccine is currently available.

The clinical trial involved six UK sites, including University Hospital Southampton. Volunteers took part locally at the NIHR Southampton Clinical Research Facility (CRF).

The new oral vaccine was shown to provide significant protection. There weren’t any safety concerns.

‘Major global health challenge’

Paratyphoid fever is caused by a type of salmonella bacteria.

It accounts for around 30% of enteric fever around the world. Together with typhoid fever, enteric fever leads to more than 100,000 deaths each year.

The trial of the new vaccine was led by researchers in Oxford. Results have been published in the New England Journal of Medicine.

Professor Saul Faust, Director of the NIHR Southampton CRF, led Southampton’s involvement in the trial.

He said: "We’re proud to have played a key role in this landmark study. Paratyphoid fever is a major global health challenge, and these results bring us closer to a vaccine that could save countless lives in regions where the disease is most prevalent."

Controlled infection

The study tested the vaccine CVD 1902 on 72 healthy adults aged 18 to 55.

Participants received two doses before being exposed to Salmonella Paratyphi A under controlled conditions.

Results showed the vaccine was 73% effective, with no serious safety concerns and only mild side effects reported.

Dr Naina McCann, Clinical Research Fellow at the Oxford Vaccine Group and lead author, said:

“This is the first time a modern-day vaccine has been shown to protect people against Salmonella Paratyphi A. By using a controlled human infection model, we were able to show that this vaccine was effective using only a small number of participants, greatly accelerating the path to a licensed vaccine.”

New hope through research

More studies are underway to confirm these results and develop combined vaccines for typhoid and paratyphoid.

Professor Sir Andrew Pollard, Director of the Oxford Vaccine Group and co-senior author, said:

“We are in a constant fight against bacterial infections, like paratyphoid, that threaten the lives of children in some of the most resource-poor regions of the world. This study provides hope that this important disease could be controlled by vaccination if the same effects can be obtained in real-life conditions in those communities.”

The trial was funded by the UK Medical Research Council and NIHR Oxford Biomedical Research Centre. It was delivered with collaboration from Bharat Biotech and the University of Maryland.