The Resurgence of Yellow Fever Outbreaks in Nigeria; A 2-Year Review 2017-2019

Abstract

Background Yellow fever outbreaks are documented to have a considerable impact not only on the individuals but on the health system with significant economic implications. Efforts to eliminate yellow fever outbreaks globally through the EYE strategy remains important following outbreaks in Africa, Nigeria included. The outbreaks reported in Nigeria, since 2017 and the response efforts provide an opportunity to document and guide interventions for improving future outbreaks in Nigeria and other countries in Africa. Methods We reviewed the available yellow fever surveillance and vaccination response data between September 2017 and September 2019 across the 36 states across Nigeria. We described the epidemiology of the difference outbreaks and the periods for all interventions. We also documented the emergency vaccination responses as well as preventive mass vaccinations implemented towards improving population immunity and limiting epidemic potentials in Nigeria.Results A total of 7,894 suspected cases with 287 laboratory-confirmed cases were reported in Nigeria between September 2017 and September 2019 with a mean age of 19 years and a case fatality of 2.7% amongst all reported cases. Outbreaks were confirmed in 55 LGAs with most of the outbreaks across four major epicentres in Kwara/Kogi, Edo, Ebonyi and Bauchi states. In response to these outbreaks, eight reactive vaccination campaigns, supported through ICG applications, were implemented. The duration for responding to the outbreaks ranged from 15-132 days (average 68 days) and a total of 45,648,242 persons aged <45 years vaccinated through reactive and preventive mass campaigns between September 2017 and September 2019.Conclusions Nigeria experienced intermediate outbreaks of yellow fever between September 2017 and 2019 with vaccination responses conducted to control these outbreaks. However, there are delays in the timeliness of responses and more efforts required in improving reporting, response times and preparedness to further prevent morbidity and mortality from the yellow fever disease outbreaks.

The Resurgence of Yellow Fever in Oyo State, Nigeria: What’s the Missing Link?

“…This could also be as a result of the level of exposure of individuals in this age group to the disease vector as observed in Delta and Enugu state. On the contrary, ndings from the Kwara state outbreak in 2017 show that individuals below 15 years (55%) were mostly affected (13). Children below the age of 10 years accounted for 35 % of all reported suspected cases between 2013 and 2015 and this is similar with observation by Tomashek et al, 2019 that due to increasing natural immunity with age in Africa, infants and children are often mostly affected during yellow fever outbreaks.…”

Changing epidemiology of yellow fever virus in Oyo State, Nigeria

“…After many years of no confirmed yellow fever case in Oyo State, a probable case was recorded in 2017 and this coincides with the same period for the same year of Nigeria’s first confirmed case in 21 years [ 14 ] which was reported in neighboring Kwara State. Then followed another 3 confirmed cases in the year 2019 and yet another 5 new cases in 2020 with an incidence rate per 100, 000 population rising from 0% to 2013 to 3.5% in 2019 and 5.6% in 2020.…”

“…This could also be as a result of the level of exposure of individuals in this age group to the disease vector as observed in Delta and Enugu states. On the contrary, findings from the Kwara state outbreak in 2017 show that individuals below 15 years (55%) were mostly affected [ 14 ]. Children below the age of 10 years accounted for 35% of all reported suspected cases between 2013 and 2015 and this is similar to observation by Tomashek et al, 2019 that due to increasing natural immunity with age in Africa, infants and children are often most affected during yellow fever outbreaks.…”