Oxford Study Shows 73% Efficacy for First Paratyphoid A Vaccine Candidate

An Oxford University (搜索)搜索该词条-led study has demonstrated that an oral live-attenuated vaccine candidate, CVD 1902查看药品详情, provided 73% protection against Salmonella Paratyphi A (搜索)搜索该靶点 infection in healthy adults, marking the first time a modern vaccine has shown efficacy against paratyphoid fever (搜索)搜索该疾病. The phase 2b randomized, double-blind, placebo-controlled trial represents a significant breakthrough for a disease that affects over 2 million people annually with no currently available vaccine.

Study Design and Results

The trial, conducted by the Oxford Vaccine Group at six UK sites, enrolled 72 healthy adult volunteers aged 18 to 55. Participants received two oral doses of the CVD 1902查看药品详情 vaccine or placebo, administered 14 days apart. Four weeks after the second dose, volunteers were deliberately exposed to S. Paratyphi A under carefully monitored conditions using a controlled human infection model.

Within 14 days of challenge, only 21% of participants in the vaccine group were diagnosed with infection compared to 75% in the placebo group, yielding a vaccine efficacy of 73% (95% CI, 46-86). The study identified no vaccine-related serious adverse events, with side effects generally mild to moderate in both groups.

Addressing Critical Medical Need

Enteric fever (搜索)搜索该疾病, caused by Salmonella Typhi查看药品详情 and Salmonella Paratyphi, leads to more than 100,000 deaths and over 8 million disability-adjusted life years annually. Approximately 30% of cases—over 2 million each year—are caused by S. Paratyphi A, for which no vaccine is currently available. According to the U.S. CDC, most people in the United States with typhoid and paratyphoid fever (搜索)搜索该疾病 are infected while traveling internationally.

Dr. Naina McCann, Clinical Research Fellow at the Oxford Vaccine Group and lead author, emphasized the significance of the findings: "This is the first time a modern-day vaccine has been shown to protect people against Salmonella Paratyphi A (搜索)搜索该靶点, a disease that affects millions of people every year. 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."

Global Health Impact

Professor Sir Andrew Pollard, Director of the Oxford Vaccine Group and co-senior author, highlighted the broader implications for global health: "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."

Future Development

Professor Xinxue Liu, Associate Professor of Medical Statistics and Epidemiology at the Oxford Vaccine Group and co-senior author, noted the broader context of enteric fever (搜索)搜索该疾病 prevention: "While typhoid conjugate vaccines have been introduced in eight countries, there are no currently licensed vaccines for paratyphoid fever (搜索)搜索该疾病. Our study marks an important step toward developing paratyphoid vaccines as part of broader efforts to control enteric fever."

Oxford is currently conducting additional studies evaluating two new bivalent typhoid-paratyphoid conjugate vaccine candidates, aiming to accelerate progress toward comprehensive enteric fever (搜索)搜索该疾病 prevention globally.

The research was funded by the UK Medical Research Council and the National Institute for Health and Care Research Oxford Biomedical Research Centre, with collaboration from Bharat Biotech International Ltd查看公司主页. and the University of Maryland查看公司主页, where the vaccine was originally engineered.