Effectiveness of the PPR Sungri-96 Vaccine in Sheep and Goats in India: A Nationwide Post-Vaccination Seromonitoring Study Towards PPR Elimination

India launched a nationwide Peste des Petits Ruminants (PPR) Eradication Programme in 2023 with the objective of achieving countrywide control and elimination of PPR by 2030, adapting a systematic mass vaccination, surveillance, and seromonitoring strategy in alignment with the WOAH/FAO Global Control and Eradication Strategy (GCES) under the PPR Global Eradication Programme (PPR-GEP) 2030. As part of the first round of mass vaccination, the present study evaluates the effectiveness of the PPR Sungri-96 (Lineage IV) vaccine in sheep and goats in fields across all the states in India, with particular emphasis on the post-vaccination evaluation (PVE) as per WOAH guidelines. A total of 24,542 post-vaccination (30–90 days) serum samples were collected from sheep and goats aged 6–12 months from 2528 epidemiological units (epi-units, villages) across 24 states of India, following GCES guidelines. Sampling was conducted according to state vaccination schedules during January 2023–December 2024, ensuring appropriate post-vaccination immune-response windows. Serum samples were analysed to detect PPR virus (PPRV)-specific antibodies using the native PPR competitive ELISA (c-ELISA) kit. The study demonstrated an overall post-vaccination seroconversion rate of 69.3% (95% CI: 68.7–69.8%) among small ruminants, indicating a substantial vaccine-induced immune response under field conditions in the target age group with desirable vaccine effectiveness. Exceptionally high post-vaccination seroconversion was observed in Telangana (91.6%) and Andhra Pradesh (82.3%), reflecting effective implementation of vaccination campaigns in these two states. Overall, 61% (1553/2528) of the evaluated epi-units recorded 70% seroconversion post vaccination, whereas 22% (510/2287) of epi-units showed ≥70% seroprevalence pre vaccination in sheep and goats aged 6 to 12 months. These findings demonstrate the effectiveness of the PPR Sungri-96 vaccine in inducing protective immunity under field conditions in accordance with GCES guidelines. The observed inter-state variations in immune response may be attributed to differences in vaccination coverage, implementation efficiency, animal demographics, husbandry practices, and local epidemiological conditions. However, some states failed to achieve the desired level of post-vaccination immunity, indicating the need for intensified vaccination efforts and improved campaign implementation in such regions. Continued mass vaccination, strengthened surveillance, real-time disease monitoring, farmer awareness programs, and capacity-building initiatives for veterinary services are critical for improving vaccine effectiveness and accelerating progress towards a PPR-free India. This study provides important field evidence supporting the effectiveness of the PPR Sungri-96 vaccine and contributes significantly to both national and global PPR eradication initiatives.