Global yellow fever update, 2020/Mise a jour sur la fievre jaune dans le monde, 2020.

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Date: Aug. 20, 2021
From: Weekly Epidemiological Record(Vol. 96, Issue 33)
Publisher: World Health Organization
Document Type: Article
Length: 9,598 words
Lexile Measure: 1730L

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2020 in review

In 2020, yellow fever (YF) outbreaks re-emerged in parts of western Africa, and widespread transmission was documented in other parts of Africa and in the Americas. The number of countries that reported YF outbreaks in Africa was the highest since 2009; 7 additional countries in west and central Africa reported YF confirmed cases. In the Americas, YF cases were confirmed between June 2020 and June 2021 in settings with low population immunity in Brazil, French Guiana and Peru.

The increased YF transmission in 2020 illustrates the continued risk posed by sylvatic transmission and spill-over into susceptible populations. The re-emergence of YF outbreaks in Guinea and Senegal, in areas that had previously benefited from large-scale vaccination through the YF initiative (2006-2014), is a sobering reminder of the importance of achieving and sustaining equitable, high vaccination coverage of all at-risk populations (Maps 1-3).

The COVID-19 pandemic presented an additional challenge to YF control, particularly between March and August 2020, with negative impacts on YF surveillance, interruption of vaccination campaigns and routine immunization (RI) services. YF prevention activities regained momentum in the subsequent months, and 48 million people were protected against YF for life in 2020 in reactive and preventive campaigns in Africa--a marked increase from 2019. This remarkable achievement was supported by YF stakeholders at all levels, from countries to global partners, and identification of innovative solutions to support countries in safe YF vaccination with mitigation of COVID-19 risk.

The Eliminate Yellow fever Epidemics (EYE) strategy supports countries in optimizing use of stretched public health and primary health-care resources for YF prevention while also conducting COVID-19 vaccination and maintaining other essential services.

Detailed epidemiological update

African Region

During the past year, many countries reported YF outbreaks and cases with outbreak potential (Map 1 and Table 1). The re-emergence of YF outbreaks in Guinea and Senegal indicates failure of routine immunization (RI) to sustain the gains of past mass campaigns and highlighted the increased risk of YF outbreaks as immunity gaps increase. As reflected in Table 3, Part B, it is feared that similar outbreaks could occur in other high-risk countries in West or Central Africa that previously completed campaigns but reported suboptimal RI coverage or in high-risk countries that are currently conducting campaigns in a context of suboptimal RI (Table 3).

YF outbreaks and responses

* Nigeria. In 2020, 3426 suspected cases were reported, of which 145 were confirmed either by the regional reference laboratory (RRL) or in country polymerase chain reaction (PCR). (1) Most confirmed cases (95% of cases, n=138) were notified from July onwards, in numerous outbreaks, particularly in southern and eastern Nigeria. Focal outbreaks in rural areas were documented in Bauchi, Benue, Borno, Delta, Ebonyi and Enugu states from November 2020, although investigations indicated delays in notification, with probable index cases dating from July 2020 in some states. There was an approximate 20% decrease in the number of suspected cases relative to 2019. The outbreak in some areas of Enugu and Ebonyi necessitated a reactive vaccination campaign in...

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Gale Document Number: GALE|A673721112