Ameme Donne Kofi, Yeboah Yaw Ofori, Odoom John Kofi, Djokoto Senanu Kwesi, Akyereko Ernest, Mamudu Abdulaziz, Diwura Mukaila, Opare William, Avevor Patrick, Diamenu Stanley, Ohene Sally-Ann, Kenu Ernest, Asiedu-Bekoe Franklin
Ghana Field Epidemiology and Laboratory Training Programme, University of Ghana School of Public Health, Accra, Legon, Ghana.
Public Health Division, Ghana Health Service, Accra, Ghana.
Arch Public Health. 2023 Jan 4;81(1):1. doi: 10.1186/s13690-022-01021-y.
The global switch from trivalent oral poliovirus vaccine (OPV) to bivalent OPV in April 2016 without corresponding co-administration of inactivated poliovirus vaccine (IPV) until June 2018, created a cohort of poliovirus type 2 naïve children with risk of developing vaccine-derived poliovirus type 2 (VDPV2). In November and December 2019, two cases of circulating vaccine-derived poliovirus type 2 (cVDPV2) were confirmed in quick succession through Acute Flaccid Paralysis (AFP) surveillance in two nomadic pastoralist settlements in Oti Region. We investigated to determine the outbreak extent, identify risk factors and implement control and preventive measures.
We interviewed case-patients' families, abstracted immunization records, assessed AFP surveillance and conducted rapid OPV and IPV vaccination coverage surveys. Using AFP case definition of any child less than 15 years in the community with sudden onset of paralysis from July to November 2019 (in case-patient 1's district) and August to December 2019 (in case-patient 2's district), we conducted active case search. Stool samples from apparently healthy children and close contacts of the case-patients were collected and tested for poliovirus. We conducted environmental assessment of the community to identify potential risk factors.
Case-patient 1 was an eight-year-old female who had taken two doses of OPV while case-patient 2 was an eight-month-old male who had taken three out of required four OPV doses in addition to IPV at seven months. Families of both case-patients had either travelled to or received visitors from areas with confirmed cVDPV2. Of all children surveyed, eight (29.6%) of 27 and three (18.8%) of 16 eligible children in communities of case-patient 1 and 2 respectively had received required four doses of OPV. No AFP case was found in both communities and surrounding settlements. Both communities had no source of potable water and toilet facilities. A stool sample from a contact of case-patient 1 tested positive for cVDPV2.
Outbreaks of cVDPV2 occurred in insanitary, under-vaccinated nomadic pastoralist settlements in Oti Region. Three rounds of monovalent OPV vaccination campaigns for children under 5 years of age in the districts and region as well as countrywide IPV vaccination campaign for poliovirus type 2 naïve cohort were conducted.
2016年4月全球从三价口服脊髓灰质炎疫苗（OPV）切换到二价OPV，直到2018年6月才相应地同时接种灭活脊髓灰质炎病毒疫苗（IPV），这导致了一批未接触过2型脊髓灰质炎病毒的儿童，他们有感染疫苗衍生2型脊髓灰质炎病毒（VDPV2）的风险。2019年11月和12月，通过对奥蒂地区两个游牧牧民定居点的急性弛缓性麻痹（AFP）监测，相继确诊了两例2型循环疫苗衍生脊髓灰质炎病毒（cVDPV2）病例。我们进行调查以确定疫情范围，识别风险因素并实施控制和预防措施。
我们采访了病例患者的家属，提取了免疫记录，评估了AFP监测情况，并开展了快速OPV和IPV疫苗接种覆盖率调查。利用2019年7月至11月（病例患者1所在地区）以及8月至12月（病例患者2所在地区）社区内任何15岁以下突然出现麻痹症状儿童的AFP病例定义，我们进行了主动病例搜索。采集了明显健康儿童和病例患者密切接触者的粪便样本并检测脊髓灰质炎病毒。我们对社区进行了环境评估以识别潜在风险因素。
病例患者1是一名8岁女性，接种了两剂OPV；病例患者2是一名8个月大男性，除7个月时接种IPV外，应接种的4剂OPV中接种了3剂。两名病例患者的家庭都曾前往有确诊cVDPV2的地区或接待过来自这些地区的访客。在所有接受调查的儿童中，病例患者1所在社区2中27名符合条件的儿童中有8名（29.6%）、病例患者2所在社区16名符合条件的儿童中有3名（18.8%）接种了所需的4剂OPV。两个社区及其周边定居点均未发现AFP病例。两个社区均没有饮用水源和厕所设施。病例患者1一名接触者的粪便样本检测出cVDPV2呈阳性。
cVDPV2疫情在奥蒂地区卫生条件差、疫苗接种率低的游牧牧民定居点爆发。在各地区、该地区以及全国范围内，针对5岁以下儿童开展了三轮单价OPV疫苗接种活动，并针对未接触过2型脊髓灰质炎病毒的人群开展了IPV疫苗接种活动。
