Top 5 Takeaways

1. Outbreak Identification: A vaccine-derived poliovirus type 2 (VDPV2) was identified in Tajikistan in January 2021, with cases indicating local transmission and genetic links to a strain from Pakistan.
2. Risk Assessment and Vaccine Selection: The Tajik Ministry of Health and Social Protection of the Population (MoHSPP) determined that the novel OPV type 2 (nOPV2) was the best option to respond to the outbreak and maintain the polio-free status of the WHO European Region.
3. Emergency Use Listing: WHO granted Emergency Use Listing status for nOPV2 in November 2020, and Tajikistan was the first country outside the WHO African Region to use it.
4. Immunization Campaigns: Three rounds of supplementary immunization activities (SIAs) were conducted, targeting children aged 0–65 months in the first two rounds and 0–55 months in the third round, achieving >99% coverage.
5. Successful Containment: A total of 31 cVDPV2 cases were confirmed, with no new cases after the second SIA, indicating successful interruption of transmission.

Original Article Author and Citation

Corresponding Author

Patrick O’Connor, gyp8@cdc.gov

Suggested Citation

O’Connor P, Huseynov S, Nielsen CF, et al. Notes from the Field: Readiness for Use of Type 2 Novel Oral Poliovirus Vaccine in Response to a Type 2 Circulating Vaccine-Derived Poliovirus Outbreak — Tajikistan, 2020–2021. MMWR Morb Mortal Wkly Rep 2022;71:361–362. DOI: http://dx.doi.org/10.15585/mmwr.mm7109a4

Summary

In January 2021, a vaccine-derived poliovirus type 2 (VDPV2) was detected in Tajikistan, indicating local transmission and genetic links to a strain from Pakistan. The Tajik Ministry of Health and Social Protection of the Population (MoHSPP) selected the novel OPV type 2 (nOPV2) for outbreak response, which was the first use of nOPV2 outside the WHO African Region. Three rounds of supplementary immunization activities (SIAs) were conducted, achieving >99% coverage and successfully interrupting transmission.

Methods

The MoHSPP conducted a rigorous risk assessment and completed the 25 Emergency Use Listing readiness criteria for nOPV2. The immunization campaign included three rounds of SIAs targeting children aged 0–65 months in the first two rounds and 0–55 months in the third round. High-quality outbreak response activities were assessed via lot quality assurance sampling.

Discussion

The outbreak response in Tajikistan demonstrated the effectiveness of nOPV2 in controlling a cVDPV2 outbreak. The successful implementation of SIAs and high coverage rates were critical in interrupting transmission. The experience highlights the importance of preparedness and rapid response in maintaining polio-free status in regions at risk of poliovirus reintroduction.

Conclusion

The use of nOPV2 in Tajikistan was a significant step in controlling the cVDPV2 outbreak and preventing further transmission. The high coverage rates achieved through SIAs were instrumental in this success. Continued vigilance and preparedness are essential for maintaining polio-free status and responding to future outbreaks.

This has been your booster shot of MMWR Info! Please check back for more MMWR, Public Health, and Programming Tutorial content daily.