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Published on: January 28, 2019
Effectiveness of monovalent rotavirus vaccine among young children in Pakistan: a test-negative case-control
Syed Asad Ali1, Shazia Sultana1, Atif Riaz1
1Aga Khan University, Karachi, Pakistan.
Insights
Two doses of the Rotarix (RV1) vaccine offer fair protection against rotavirus disease in Pakistan, a high-burden country. Further vaccination strategies are recommended for continued disease reduction.
Area of Science:
- Pediatric Infectious Diseases
- Vaccinology
- Public Health Surveillance
Background:
- Pakistan faces a high burden of childhood rotavirus mortality.
- The monovalent oral rotavirus vaccine, Rotarix (RV1), was introduced into the national immunization program in 2017.
- A two-dose schedule is administered at 6 and 10 weeks of age.
Purpose of the Study:
- To evaluate the effectiveness of the Rotarix (RV1) vaccine in preventing severe rotavirus gastroenteritis requiring hospitalization.
- To assess vaccine effectiveness in a real-world setting in Pakistan.
Main Methods:
- Active surveillance for rotavirus gastroenteritis was conducted in 9 hospitals across 3 provinces from April 2018 to March 2023.
- Children eligible for vaccination were enrolled; cases tested positive for rotavirus, and controls tested negative via enzyme immunoassay (EIA).
- Unconditional logistic regression was used to estimate the effectiveness of two RV1 doses versus zero doses.
Main Results:
- The study analyzed 517 rotavirus cases and 1310 controls among children with available vaccination data.
- Two RV1 doses showed 33% effectiveness against hospital care for rotavirus in children aged 22 weeks-11 months.
- Effectiveness was higher (45%) in better-nourished children and varied by rotavirus genotype detected.
Conclusions:
- Two doses of RV1 provide moderate protection in a high rotavirus burden setting like Pakistan.
- Continued pursuit of additional vaccination strategies is crucial for further reducing rotavirus disease burden.
- The findings underscore the importance of ongoing vaccine efficacy monitoring and strategy refinement.
Background:
Pakistan ranks among top 4 countries with greatest number of rotavirus deaths among young children. To reduce the burden of severe rotavirus disease, Pakistan introduced monovalent oral rotavirus vaccine, Rotarix (RV1), into its routine immunization program in one area in early 2017 and reached all areas by April 2018, using a 2-dose schedule at ages 6 and 10 weeks.
Methods:
During April 2018 through March 2023, we performed active surveillance for acute rotavirus gastroenteritis resulting in intravenous hydration at 9 hospitals in 3 provinces among children eligible to have received rotavirus vaccine. Cases were enrolled children whose stool sample tested positive for rotavirus by enzyme immunoassay and controls were those testing negative. Unconditional logistic regression was used to estimate the effectiveness of 2 doses of RV1 vs 0 doses in reducing likelihood of hospital care for rotavirus disease.
Results:
Overall, 6454 children aged 22 weeks-59 months were eligible for enrollment and a stool sample was tested by EIA in 4833 (75%). Among children with an EIA result, rotavirus vaccination information was available on 78% (3774/4833). Based on 517 rotavirus cases and 1310 controls, the effectiveness of 2 RV1 doses vs 0 doses among children aged 22 weeks-11 months was 33% (95% CI 12-49); the effectiveness was 45% (95% CI 21-62) among those better nourished by weight-for-age z-score (WAZ ≥-2). Among children aged 1 year, the effectiveness was 24% (95% CI -20 - 52). A wide array of genotypes were detected and nearly 40% of cases with genotype results had >1 G and/or >1 P genotype identified. Vaccine effectiveness point estimates were lowest for those with genotype P[4] detected vs those with P[8] or P[6] detected.
Conclusion:
2 RV1 doses appear to provide fair protection in this very high burden setting. Additional vaccination strategies should continue to be pursued for children in this and similar locations.
