Revealing measles cases in Vietnam during the spread of a new coronavirus infection

Abstract

Introduction. According to the WHO Strategic Plan, five out of six geographical regions were expected to achieve measles elimination by 2020, among which is the Western Pacific Region (WPR), which includes the Socialist Republic of Vietnam (VNM). In 2019, 14 156 measles cases were detected in Vietnam, which significantly exceeds the level required to achieve its elimination (less than 1 case per 1 million population). Analyzing the causes of the ongoing measles virus circulation in diverse global regions is very important. It is also important to assess a potential impact on the measles incidence due to anti-epidemic measures aimed at combating the COVID-19 pandemic. This research is devoted to revealation measles cases in South Vietnam within the period covering January 2020 to March 2021. Materials and methods. 799 samples of blood sera obtained from different territories of South Vietnam in 2020–2021 were examined for IgM antibodies against measles virus using the Anti-Measles Virus ELISA (IgM) test system (Euroimmun, Germany). The presence of IgM measles virus antibodies in the blood serum was assessed as an acute measles infection. Results. The measles virus was actively circulating in South Vietnam in the first months of 2020. Residents of large cities and industrial centers were mainly involved in the epidemic process. Measles spread mainly among unvaccinated (71.58%) subjects, or who was unaware of vaccinations (25.48%), but also among those who were vaccinated (2.12%) and revaccinated (0.64%). The absolute majority of cases (71%) affected children under the age of three, with a predominance of those at the first year of life. Among the latter, 48% were children aged 7-9 months old. In March- April 2020, there was a sharp decrease in the number of measles cases in South Vietnam, down to a sporadic level (from May 2020 to March 2021). This is probably due to the anti-epidemic measures that were carried out in the VNM in order to limit the spread of COVID-19. Consequently, after the restrictions are lifted, we can expect an increase in the measles incidence in VNM.