Dynamics of the frequency of hospitalizations of children under 5 years of age with rotavirus infection in the absence of universal vaccination against rotavirus (15-year follow-up)

Abstract

Purpose - to monitor the dynamics of the frequency of hospitalization of children under 5 years of age with rotavirus infection during 15 years in the absence of universal vaccination and to determine the burden of rotavirus infection and the feasibility of introducing a rotavirus vaccine into the National Vaccination Calendar.

Materials and methods. Active surveillance of rotavirus infection among hospitalized children under 5 years of age was conducted according to a standard protocol prepared by WHO for the global rotavirus infection surveillance network. A comparison was made of the frequency of hospitalization of children under 5 years of age with rotavirus acute gastroenteritis (AGE) by sentinel years. Stool samples were collected within 2 days of hospitalization and sent to the virology laboratory for testing. Detection of rotavirus was carried out using ELISA. Genotyping of rotaviruses was carried out in WHO laboratories by the method of multiplex RT-PCR.

Results. During 15 years (2007-2021) of observation, there were 7,821 children under the age of 5 who were hospitalized in connection with an acute intestinal infection at the Kyiv Surveillance Center. Rotavirus infection was determined in 3387 children (43.3%). A consistently high frequency of hospitalizations with rotavirus AGE was observed with a slight downward trend over the years (from 50-75% in the first years to 33-39% in 2018-2019). In 2021 (the 15^th year of observation), the average annual frequency of rotavirus AGE decreased even more significantly and amounted to 21% (a 61% decrease compared to the first years of observation). The unexpected decrease in the frequency of rotavirus diarrhea among hospitalized children in the 15^th year of observation in the absence of universal vaccination against rotavirus is difficult to explain. A number of factors could have contributed to the above-mentioned decrease, the most likely of which could be the coincidence in time with the epidemic of COVID-19, in which anti-epidemic measures are similar to those for intestinal infections. While the average annual frequency of hospitalizations with rotavirus infection decreased, the frequency of hospitalizations remained high in certain months of the year, starting from January to June, which increased the burden on inpatients in certain, mostly cold, months of the year. Further active monitoring of rotavirus infection is necessary to definitively resolve the issue of whether the decrease in the frequency of rotavirus infection by the 15^th year is temporary or is a natural course of the epidemic process and will continue to occur.

Conclusions. In Ukraine, in the absence of universal vaccination against rotavirus, during the 15-year (2007-2021) observation period, a consistently high frequency of rotavirus infection was noted among hospitalized children under 5 years of age with AGE, with a slight downward trend over the years. In the 15^th year of follow-up (2021), there was an unusual decline in the proportion of rotavirus infection among hospitalized children, which may have been contributed to by a number of factors, the most likely of which could be the coincidence in the period with the COVID-19 epidemic, in which anti-epidemic measures are similar to those for intestinal infections.

Even with a decrease in the average annual frequency of rotavirus AGE in the 15^th year of observation, a consistently high rate of hospitalization with rotavirus gastroenteritis remains in certain months of the year, which increases the burden on inpatients. The significant burden of rotavirus infection among children under the age of 5 years old determines the expediency of including the rotavirus vaccine in the National Vaccination Calendar of Ukraine.

The research was carried out in accordance with the principles of the Helsinki Declaration. The study protocol was approved by the Local Ethics Committee of all participating institutions. The informed consent of the patient was obtained for conducting the studies.

No conflict of interests was declared by the authors.