Breakthrough in Paratyphoid Fever Vaccine: Oxford-led Study Shows 73% Efficacy in Healthy Adults

Strategic Insights -

A groundbreaking study published in The New England Journal of Medicine has demonstrated the efficacy of a vaccine against Salmonella Paratyphi A infection, a major contributor to enteric fever that causes over 100,000 deaths and 8 million disability-adjusted life years annually. The Oxford-led research used a controlled human infection model to show that the oral live-attenuated vaccine, CVD 1902, provided significant protection against S. Paratyphi A infection in healthy adults without any safety concerns.

Key Takeaways:

  • The study, conducted by the Oxford Vaccine Group, enrolled 72 healthy adult volunteers aged 18 to 55 and demonstrated a vaccine efficacy of 73% (95% CI, 46-86) against S. Paratyphi A infection.
  • The vaccine, CVD 1902, was administered orally in two doses, 14 days apart, and participants were deliberately exposed to S. Paratyphi A under carefully monitored conditions four weeks after the second dose.
  • No vaccine-related serious adverse events were identified, and side effects were generally mild to moderate in both the vaccine and placebo groups.
  • Dr. Naina McCann, lead author, emphasized the importance of this breakthrough, stating that this is the first time a modern-day vaccine has been shown to protect people against Salmonella Paratyphi A.
  • The study was funded by the UK Medical Research Council (MRC) and the National Institute for Health and Care Research (NIHR) Oxford Biomedical Research Centre, with collaboration from Bharat Biotech International Ltd. and the University of Maryland.
  • The Oxford Vaccine Group is now conducting additional studies evaluating two new bivalent typhoid-paratyphoid conjugate vaccine candidates, aiming to accelerate progress toward comprehensive enteric fever prevention globally.
  • Professor Sir Andrew Pollard highlighted the importance of developing vaccines for bacterial infections, such as paratyphoid, that threaten the lives of children in resource-poor regions worldwide.
  • Professor Xinxue Liu emphasized that while typhoid conjugate vaccines have been introduced in eight countries, there are no currently licensed vaccines for paratyphoid fever, making this study a crucial step toward developing paratyphoid vaccines.

Statistics:

  • 72 healthy adult volunteers aged 18 to 55 were enrolled in the study.
  • A 73% vaccine efficacy (95% CI, 46-86) was achieved against S. Paratyphi A infection.
  • 21% of participants in the vaccine group and 75% in the placebo group were diagnosed with infection within 14 days of challenge.
  • The study showed no vaccine-related serious adverse events and side effects were generally mild to moderate in both groups.
  • Enteric fever causes over 100,000 deaths and 8 million disability-adjusted life years annually, with around 30% of cases, over 2 million annually, caused by S. Paratyphi A.

Sources:

  • The New England Journal of Medicine
  • University of Oxford
  • UK Medical Research Council (MRC)
  • National Institute for Health and Care Research (NIHR) Oxford Biomedical Research Centre
  • Bharat Biotech International Ltd.
  • University of Maryland
  • Department of Paediatrics, University of Oxford
  • Oxford Vaccine Group