Health impact of routine immunisation service disruptions and mass vaccination campaign suspensions caused by the COVID-19 pandemic: Multimodel comparative analysis of disruption scenarios for measles, meningococcal A, and yellow fever vaccination in 10 low- and lower middle-income countries

Background: Childhood immunisation services have been disrupted by the COVID-19 pandemic. WHO recommends considering outbreak risk using epidemiological criteria when deciding whether to conduct preventive vaccination campaigns during the pandemic. Methods: We used 2-3 models per infection to estimate the health impact of 50% reduced routine vaccination coverage in 2020 and delay of campaign vaccination from 2020 to 2021 for measles vaccination in Bangladesh, Chad, Ethiopia, Kenya, Nigeria, and South Sudan, for meningococcal A vaccination in Burkina Faso, Chad, Niger, and Nigeria, and for yellow fever vaccination in the Democratic Republic of Congo, Ghana, and Nigeria. Our counterfactual comparative scenario was sustaining immunisation services at coverage projections made prior to COVID-19 (i.e. without any disruption). Findings: Reduced routine vaccination coverage in 2020 without catch-up vaccination may lead to an increase in measles and yellow fever disease burden in the modelled countries. Delaying planned campaigns in Ethiopia and Nigeria by a year may significantly increased the risk of measles outbreaks (both countries did complete their SIAS planned for 2020). For yellow fever vaccination, delay in campaigns leads to a potential disease burden rise of >1 death per 100,000 people until the campaigns are implemented. For meningococcal A vaccination, short term disruptions in 2020 are unlikely to have a significant impact due to the persistence of direct and indirect benefits from past introductory campaigns of the 1 to 29-year-old population, bolstered by inclusion of the vaccine into the routine immunisation schedule accompanied by further catch-up campaigns. Interpretation: The impact of COVID-19-related disruption to vaccination programs varies between infections and countries. Planning and implementation of campaigns should consider country and infection-specific epidemiological factors and local immunity gaps worsened by the COVID-19 pandemic when prioritising vaccines and strategies for catch-up vaccination.

背景：儿童免疫服务因新冠疫情而中断。世卫组织建议在决定疫情期间是否开展预防性疫苗接种运动时，使用流行病学标准考虑疫情爆发风险。 方法：针对每种感染，我们使用2 - 3种模型来估计2020年常规疫苗接种覆盖率降低50%，以及2020年至2021年孟加拉国、乍得、埃塞俄比亚、肯尼亚、尼日利亚和南苏丹的麻疹疫苗接种、布基纳法索、乍得、尼日尔和尼日利亚的A群脑膜炎球菌疫苗接种以及刚果民主共和国、加纳和尼日利亚的黄热病疫苗接种运动推迟所产生的健康影响。我们的反事实比较情景是按照新冠疫情前（即无任何中断情况）所做的覆盖率预测维持免疫服务。 发现：2020年常规疫苗接种覆盖率降低且无补种疫苗的情况可能导致模拟国家的麻疹和黄热病疾病负担增加。埃塞俄比亚和尼日利亚将计划中的疫苗接种运动推迟一年可能会显著增加麻疹爆发的风险（这两个国家都完成了2020年计划的补充免疫活动）。对于黄热病疫苗接种，在疫苗接种运动实施之前，运动推迟可能导致每10万人中潜在疾病负担增加超过1例死亡。对于A群脑膜炎球菌疫苗接种，由于过去针对1 - 29岁人群开展的推广运动所带来的直接和间接益处持续存在，并且该疫苗已纳入常规免疫计划同时伴有进一步的补种运动，2020年的短期中断不太可能产生重大影响。 解释：新冠疫情相关的疫苗接种计划中断所产生的影响因感染疾病和国家而异。在确定疫苗接种的优先级以及补种疫苗的策略时，疫苗接种运动的规划和实施应考虑具体国家和感染疾病相关的流行病学因素以及因新冠疫情而恶化的当地免疫缺口。