Measles outbreak response immunization during the COVID-19 pandemic: lessons from Borno State, Nigeria.

Introduction: the COVID-19 outbreak was declared a public health emergency of international concern by the WHO on the 30 January 2020. The occurrence of measles outbreaks in the context of COVID-19, both highly infectious respiratory illnesses, impacts additional challenges to the health system in a state with an ongoing humanitarian crisis. This article documents the implementation of an outbreak response immunization (ORI) during the COVID-19 pandemic and the implementation of global guidelines for mass vaccination.

Methods: a retrospective review of the response to measles outbreak implemented in Borno state across six local government areas (LGAs) in 2019 was conducted. This review assessed the utilization of the World Health Organization (WHO) decision making framework, measles and COVID-19 epidemiological reports and the measle's vaccination response data.

Results: an outbreak response immunization was implemented in six LGAs in Borno State, with a validated post campaign coverage of 96.3% (95% CI: 93.0 - 98.1). In total, 181,634 children aged 9 months-9 years were vaccinated with 27,961 (15.4%) receiving the measles vaccine for the first time. Prior to the interventions, 20 COVID-19 cases were reported in the six LGAs while only seven suspected cases were reported with only two cases confirmed in one of the six LGAs four weeks after the ORI.

Conclusion: the WHO decision-making framework for implementing mass vaccinations in the context of the COVID-19 Pandemic was utilized for the outbreak response immunization in Borno State, Nigeria with 181,634 children aged 9 Months-9 years vaccinated with the measles vaccine. The use of the WHO decision-making framework to assess risk benefits of initiating mass vaccination campaigns remains a very important practical tool. These types of responses in Nigeria and other low and middle income countries (LMICs), with hitherto suboptimal immunization coverage and weak health systems and other settings, affected by humanitarian emergencies is essential in the achievement of the regional measle's elimination targets.