Whole genome sequencing (WGS) characterisation of Neisseria meningitidis from invasive meningococcal disease in the Czech Republic in 2018-2024 - analysis of the impact of the COVID-19 pandemic.

Objective: To analyse the impact of the COVID-19 pandemic on the epidemiological situation of invasive meningococcal disease (IMD) and molecular characteristics of Neisseria meningitidis isolates causing IMD in the Czech Republic.

Material and methods: The study was based on IMD surveillance data for 2018-2024 (as of 27 May 2024), and all available N. meningitidis isolates from IMD of these years were subjected to whole genome sequencing (WGS). To analyse the impact of the COVID-19 pandemic, the study period was divided into three parts: the pre-COVID period (2018-2019), the COVID-19 pandemic period (2020-2022), and the post-COVID period (2023-2024).

Results: As a result of the implementation of the COVID-19 control measures, similar to other countries, there has been a decline in the incidence of air-borne infections including IMD in the Czech Republic. However, unlike many other countries, there has not been a resurgence of IMD in the Czech Republic following the release of these epidemiological measures. WGS characterisation of IMD isolates showed a gradual change in the population of meningococci causing IMD in the Czech Republic during the COVID-19 and post-COVID periods. For N. meningitidis isolates of serogroups C, W, and Y, a gradual and significant decline in overall heterogeneity can be observed - from ten different clonal complexes detected in the pre-COVID period to only three in the post-COVID years (cc11, cc23, and cc103). At the same time, a significant reduction was observed in N. meningitidis C isolates; cc11. In contrast, an increase in overall heterogeneity can be observed for N. meningitidis B isolates during the COVID-19 pandemic period, followed by its decline again to overall lowest values in the post-COVID period.

Conclusion: The fact that MenB vaccine and conjugate vaccine A, C, W, Y started to be covered by health insurance for young children (in May 2020) and adolescents (in January 2022) also appears to play a role in the persistent decline of IMD in the Czech Republic. In order to maintain the low incidence of IMD in the Czech Republic, it is desirable to continue vaccination with MenB vaccine and conjugated vaccine A, C, W, Y in accordance with the recommendations of the Czech Society of Vaccinology of the Czech Medical Association of Jan Evangelista Purkyně.