Alerts in Africa
Situation at a glance Yellow fever is endemic in the WHO African Region and was among the top five most frequently reported events in the region in 2019 and 2020. Twenty-seven countries in Africa have been classified as high-risk by the Eliminate Yellow fever Epidemics (EYE) global strategy. From 1 January 2021 to 26 August 2022, a total of 12 countries in the region have reported 184 confirmed cases and 274 probable cases, including 21 deaths, reflecting ongoing complex viral transmission. Risk factors for onward spread and amplification include low population immunity, population movements, viral transmission dynamics, and climate and ecological factors that have contributed to the spread of Aedes mosquitoes. Response measures, most notably reactive and preventive vaccination campaigns, are ongoing in the affected countries. Since the beginning of 2021, over 3.9 million people have been vaccinated through reactive vaccination campaigns in Cameroon, Central African Republic, Chad, Ghana, and Kenya. Description of outbreaks In 2021, nine African countries - Cameroon, Central African Republic, Chad, Côte d´Ivoire, Democratic Republic of Congo, Gabon, Ghana, Nigeria, and Republic of the Congo - reported a total of 151 confirmed cases of yellow fever (for more details, please see the Disease Outbreak News published on 23 December 20211). Of these nine countries, six continue to report confirmed cases of yellow fever with ongoing transmission in 2022, while Côte d´Ivoire and Nigeria have reported probable cases2 and Gabon has not reported further cases since 2021. In 2022, two additional countries, Kenya3 and Uganda4, have reported confirmed cases of yellow fever. From 1 January to 26 August 2022, a total of 33 confirmed cases of yellow fever were reported from eight African countries including Central African Republic (33%, 11 cases), Cameroon (24%, eight cases), Democratic Republic of Congo (13%, four cases), Kenya (9%, three cases), Chad (6%, two cases), Republic of the Congo (6%, two cases), Uganda (6%, two cases), and Ghana (3%, one case). Ten countries - Cameroon, Central African Republic, Chad, Côte d´Ivoire, Democratic Republic of Congo, Ghana, Kenya, Niger, Nigeria, and Republic of the Congo - have also reported a total of 274 probable cases of yellow fever from 1 January 2021 to 26 August 2022 (Table 1). The majority of cases over the entire period were reported in the last quarter of 2021 (Figure 1), with Ghana reporting around 33% of all confirmed cases. Of 184 confirmed cases, 73% are aged 30 years and below, and the male-to-female ratio is 1.2. The case count and the number of outbreaks are anticipated to continue evolving as the Region enters the seasonal period when there is often an increase in cases notified. Figure 1. Probable and confirmed cases of yellow fever by week of symptom onset in countries reporting transmission in the WHO African Region, 1 January 2021 to 26 August 2022.