Salmonella Vaccine: 73% Protection in Adults – Latest News
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Promising New Vaccine Shows 73% Efficacy Against Typhoid fever Caused by *Salmonella* Paratyphi A
Table of Contents
Published November 1,2025
Overview of CVD 1902 Vaccine
Researchers have developed a new oral vaccine,CVD 1902,demonstrating significant efficacy against typhoid fever caused by Salmonella Paratyphi A. The vaccine, developed by the VASP Study Team, offers a potential solution to a major public health challenge, particularly in regions where this strain of typhoid fever is endemic. The findings were published in the New england Journal of Medicine on November 1, 2025 (“Safety, efficacy, and immunogenicity of a salmonella paratyphi a vaccine”).
Strong efficacy Against *S. Paratyphi* A Infection
A clinical trial involving 72 participants evaluated the effectiveness of CVD 1902. participants received either two doses of the vaccine or a placebo, administered 14 days apart. Twenty-eight days after the second dose, all participants were intentionally challenged with S. Paratyphi A. Results showed that only 21% of vaccinated individuals developed an infection,compared to 75% in the placebo group. This translates to a vaccine efficacy of 73% (95% Confidence Interval: 46-86%).
A per-protocol analysis, focusing on participants who adhered strictly to the study protocol, further confirmed thes results, showing a 69% efficacy (95% CI, 42-84%). the vaccine stimulated a robust immune response, evidenced by significant increases in serum IgG and IgA antibodies targeting the O antigen of S. Paratyphi A. No such immune response was observed in the placebo group.
Safety and Tolerability
The trial closely monitored participant safety.The incidence and nature of adverse events were comparable between the vaccine and placebo groups. Importantly, no serious adverse events related to the vaccine were reported. This favorable safety profile suggests that CVD 1902 is well-tolerated and suitable for potential widespread use.
Public Health Implications and Future Directions
Typhoid fever, caused by Salmonella Typhi and Salmonella Paratyphi, remains a significant global health concern, particularly in low- and middle-income countries. According to the World Health Organization (WHO), an estimated 11-20 million cases and 128,000-161,000 deaths occur annually worldwide (“Typhoid Fever”). Existing vaccines offer varying levels of protection and often require multiple doses or are not suitable for young children.
The growth of an effective oral vaccine against S. Paratyphi A, like CVD 1902, addresses a critical unmet need. If these promising results are replicated in larger, Phase 3 clinical trials, this two-dose vaccine could become a practical and effective tool for preventing enteric fever, especially in endemic regions. The strong immune response and demonstrated safety profile suggest the potential for broad implementation, protecting millions at risk.
Further research will focus on evaluating the vaccine’s efficacy in larger populations, assessing its long-term protection, and determining its effectiveness in different age groups and geographic settings. Studies are also planned to investigate the vaccine’s potential to prevent infection with other Salmonella Paratyphi serovars.
About Enteric Fever and *Salmonella* Paratyphi A
Enteric fever is a systemic illness caused by Salmonella bacteria. Typhoid fever is caused by Salmonella Typhi, while paratyphoid fever is caused by Salmonella Paratyphi A, B, and C.