Abstract
Abstract
Background
Yemen has faced one of the worst humanitarian crises in the world since the start of the war in 2015. In 2020; 30 Vaccine Derived Polio Virus type 1 (VDPV1) isolates were detected in Saadah governorate. The aims are to characterize the outbreak and address the gaps predisposing the emergence and circulation of VDPV1 in Saadah governorate, Yemen.
Method
A retrospective descriptive study of confirmed cases of VDPV1 between January and December 2020 was performed. Surveillance staff collected data from patient cases, contacts, as well as stool specimens that shipped to WHO accredited polio labs. Data of population immunity was also reviewed. The difference in days between the date of sample collection, shipment, and receiving lab result was used to calculate the average of delayed days for lab confirmation.
Results
From January to December 2020, a total of 114 cases of acute flaccid paralysis (AFP) were reported from 87% (13/15) districts, and cVDPV1 was confirmed among 26% (30) AFP cases. 75% (21) were < 5 years, 73% (20) had zero doses of Oral Polio Vaccine (OPV). The first confirmed case (3%) was from Saadah city, with paralysis onset at the end of January 2020 followed by 5 cases (17%) in March from another four districts, 8 cases (27%) in April, and 13 (43%) up to December 2020 were from the same five districts in addition to 3 (10%) form three new districts. The lab confirmation was received after an average of 126 days (71–196) from sample collection. The isolates differ from the Sabin 1 type by 17- 30 VP1 nucleotides (nt) and were linked to VDPV1 with 13 (nt) divergence that isolated in July 2020 from stool specimens collected before one year from contacts of an inadequate AFP case reported from Sahar district.
Conclusion
The new emerging VDPV1 was retrospectively confirmed after one year of sample collection from Sahar district. Delayed lab confirmation, as well as the response and low immunization profile of children against polio, were the main predisposing factors for cVDPV1 outbreak. This outbreak highlights the need to maintain regular biweekly shipments to referral polio labs in the short-term, and the exploration of other options in the longer-term to enable the Yemen National Lab to fully process national samples itself.
Publisher
Springer Science and Business Media LLC
Reference43 articles.
1. DuintjerTebbens RJ, Pallansch MA, Chumakov KM, Halsey NA, Hovi T, Minor PD, Modlin JF, Patriarca PA, Sutter RW, Wright PF, et al. Expert review on poliovirus immunity and transmission. Risk Anal. 2013;33(4):544–605.
2. Classification and reporting of vaccine-derived polioviruses. http://polioeradication.org/wpcontent/uploads/2016/09/Reporting-and-Classification-of-VDPVs_Aug2016_EN.pdf. Accessed 27 Mar 2021.
3. Nafi OA, Ramadan B. Sabin vaccine in poliomyelitis eradication: achievements and risks. J Pure Appl Microbiol. 2019;13(1):413–18.
4. Kew OM, Nottay BK, Hatch MH, Nakano JH, Obijeski JF. Multiple genetic changes can occur in the oral poliovaccines upon replication in humans. J Gen Virol. 1981;56(2):337–47.
5. Agol VI. Vaccine-derived polioviruses. Biologicals. 2006;34(2):103–8.
Cited by
8 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献