Cases of aseptic meningitis after vaccination against mumps in Russia (2009-2019).

Objectives: Mumps is a highly contagious viral infection prevented by immunization with live attenuated vaccines. Mumps vaccines have proven to be safe and effective; however, rare cases of aseptic meningitis (AM) can occur after vaccination. The range of meningitis occurrence varies by different factors (strain, vaccine producer, and so on). Monovaccines or divaccines (mumps-measles vaccine), prepared from the strain Leningrad-3 (L-3), are used in Russia. Meningitis occurrence after vaccination has been established previously as very low. Nevertheless, with the number of children being vaccinated every year, vaccine-associated AM cases still occur. There is no official statistics on AM incidence after mumps vaccines, and information on AM features as an adverse event of mumps vaccination is limited and mostly devoted to vaccines, prepared from strains other than L-3.

Study Design: The study included patients with AM who were vaccinated against mumps in the previous 30 days before the present disease onset during 2009-2019.

Methods: Patients admitted to Infectious Clinical Hospital No. 1, Moscow, Russia, with AM were observed by a pediatrician and were screened for etiological agents of meningitis.

Results: Seven patients were enrolled, and clinical features and the course of infection are presented.

Conclusions: Detection of only 7 cases of AM associated with mumps vaccination during the 10-year period supports very low occurrence of this adverse event after immunization with the L-3 strain-based mumps vaccines. Nevertheless, the annual number of AM cases that occur after mumps vaccination remains unknown and poorly diagnosed in practice because of the low awareness of physicians of this adverse reaction. Detection and objective coverage of such cases can lead to a weakening of 'antivaccination' moods in a society and to restoration of confidence in the healthcare system.