TAG: GS 3: SCIENCE AND TECHNOLOGY
THE CONTEXT: A phase-3 trial conducted in Malawi, Africa, has unveiled the sustained efficacy of Bharat Biotech’s conjugate typhoid toxoid vaccine, Typbar, challenging the threat of typhoid fever in endemic regions.
EXPLANATION:
- The study, representing the first randomized, controlled, double-blind trial of its kind, brings promising results regarding the long-term effectiveness of a single dose of the typhoid vaccine.
Typhoid’s Global Impact: The Need for Effective Vaccination
- In 2019, a staggering 9.24 million typhoid cases and 110,000 deaths were reported globally.
- The majority of these cases occurred in South-East Asia and Africa, emphasizing the urgent need for reliable and long-lasting typhoid vaccines.
- Typhoid’s prevalence and mortality underscore the significance of the recent findings in combating this infectious disease.
Bharat Biotech’s Typbar: Study Design and Participants
- The study focused on healthy children aged between nine months and 12 years, residing in a typhoid fever-endemic setting in Malawi.
- The participants were randomly assigned to receive Bharat Biotech’s Typbar or a control vaccine.
- A total of 28,130 children were recruited, with 14,069 receiving the typhoid vaccine and 14,061 receiving the control vaccine, ensuring a robust sample size for analysis.
Long-term Efficacy: A Four-Year Window
- The key revelation from the trial is the sustained efficacy of the Typbar vaccine over a median follow-up period of 4.3 years.
- The overall efficacy was found to be 70.6% for children aged nine months to two years, with even higher efficacy rates exceeding 79% for children above two years.
- This longevity of protection is crucial in the fight against typhoid, especially considering the challenges posed by the bacteria’s rebound in children aged 5-15 years.
Cumulative Vaccine Efficacy: An Encouraging Trend
- The study showcased an encouraging trend in cumulative vaccine efficacy, revealing rates of 83.4% after one year, 80.7% after two years, 80.1% after three years, 77.1% after four years, and 78.3% after 4.61 years – the longest follow-up observed.
- This trend suggests a consistent and reliable level of protection against typhoid, demonstrating the vaccine’s robustness over an extended period.
Impact on Typhoid Cases: A Significant Reduction
- During the follow-up period, children who received the Typbar vaccine exhibited a significantly lower incidence of typhoid fever compared to the control group.
- The absolute risk reduction of 6.1 typhoid infections per 1,000 vaccinated children highlights the tangible impact of the vaccine in preventing typhoid cases.
Future Directions: Booster Dose Considerations
- Acknowledging the potential waning protection over time, the researchers underscore the need for longer-duration vaccine efficacy studies.
- An ongoing immunogenicity study in Malawi is exploring the benefits of a booster dose administered nearly five years after the initial vaccination.
- This could provide insights into whether additional doses enhance and prolong the protective effect against typhoid.
Bharat Biotech’s Typbar:
- Typbar is a highly purified Vicapsular polysaccharide of Salmonella typhi Ty2.
- Typbar would also be the world’s first vegetarian or non-bovine typhoid vaccine.
- Bharat Biotech is the largest primary manufacturer of typhoid vaccine in the country.
- The company dedicated the vaccine to Dr. John R. Robbins, the father of polysaccharide vaccines.
Conclusion: A Milestone in Typhoid Prevention
- Bharat Biotech’s Typbar has emerged as a beacon of hope in the battle against typhoid, demonstrating not only immediate efficacy but also a lasting shield against infectious diseases.
- The implications of this study reach beyond Malawi, offering a potential blueprint for addressing typhoid in other endemic regions globally.
- As the research community eagerly awaits the outcomes of booster dose studies, the Typbar vaccine stands as a testament to the strides made in vaccination science for global health.
