COMPARATIVE ASSESSMENT OF RESPIRATORY SYNCYTIAL VIRUS INFECTION AND INFLUENZA IN DIFFERENT AGE GROUPS OF PATIENTS WITH ACUTE RESPIRATORY VIRAL INFECTIONS IN 2013–2019

Human respiratory syncytial virus (hRSV or RSV) is the most common cause for the lower respiratory tract infections in infants. Despite the leading role and burden of RSV infection (RSVI), the contribution of this infection to the incidence among both young and older children, as well as in people over 18 y/o, remains largely unexplored. The purposes of the research were as follows: to assess the prevalence of RSVI in certain age groups of registered patients with acute respiratory viral infections (ARVI) (0 to 2 y/o, 3 to 6 y/o, 7 to 14 y/o, and 15 y/o and older) in Russia according to traditional laboratory surveillance data; determination of seasonality in the circulation of RSV; comparison of the frequency of diagnosing influenza and RSVI in patients of certain age groups; assessment of risk groups by age among hospitalized patients with severe acute respiratory infection (SARI) caused by RSV. Materials and methods of the research: as part of the traditional laboratory surveillance on influenza and ARVI/SARS, a retrospective analysis of all cases of RSVI confirmed by polymerase chain reaction (PCR) tests was carried out in Russia for the period from Oct. 1, 2013 till Sept. 30, 2019, among 121,773 registered patients in 8 cities of Russia (Izhevsk, Irkutsk, Kazan, Perm, Petropavlovsk, Rostov-on-Don, Saint Petersburg, and Khabarovsk). Authors used aggregated weekly data for age groups (as stated above) (Order of the Russian Federal Service for Supervision of Consumer Rights Protection and Human Well-Being No. 373 dated Mar. 31, 2005). In addition, authors have analyzed and systematized the age data of 6,547 individual cards of hospitalized patients with SARI with PCR-confirmed RSVI in 5 cities of Russia (Kaliningrad, Saint Petersburg, Chita, Khabarovsk, and Vladivostok) that carry out the signaling surveillance on influenza and ARVI for the epidemiological seasons from 2013/2014 till 2018/2019 (starting the 40th week of the initial year till the 39th week of the final year). SARI was detected using the standard definition of a SARI case (body temperature 38 degrees Celsius and above lasting for at least 7 consecutive days according to the anamnesis or when seeking medical help, cough, shortness of breath, need for hospitalization) in accordance with the Guideline “Organization and conduct of a signaling clinical and laboratory epidemiological surveillance in Russia.” Thus, individual cards of all SARI patients included in the corresponding Signaling Surveillance (SS) database for the specified period were used. Results: according to the traditional laboratory surveillance, the risk group for RSVI is children aged 0 to 6 y/o. In addition, in children under 2 y/o, the frequency of detection of RSV at the peaks of the seasonal increase in the incidence was higher or comparable to the frequency of confirmation of the influenza etiology of the disease in certain epidemic seasons. According to SS, RSV-associated SARIs most often develop in children of 0 to 5 months old (32.1% of the examined patients with SARI in this age group). Conclusion: the registration of a seasonal increase in RSVI almost simultaneously with an epidemic increase in the incidence of influenza indicates an urgent need for differential diagnosis of influenza and RSVI in patients at risk, and especially in children under 6 y/o, in order to prescribe the therapy needed.