Preventive efficacy of Grippol<sup>®</sup> plus in children aged 8 to 14 years residing in Almaty (Republic of Kazakhstan)
Objective. To evaluate preventive efficacy and reactogenicity of Grippol® plus vaccine in children aged 8 to 14 years residing in Almaty (Republic of Kazakhstan). Patients and methods. This open-label prospective study was conducted between October 2019 and April 2020 and included 600 children aged 8 to 14 years (mean age 10.6 ± 4.9 years) studying in two schools of Almaty. Study participants were divided into two groups (300 children in each): experimental group, in which children were vaccinated with Grippol® plus (Petrovax Pharm, Russia) in accordance with all rules and control group. Patients in both groups were matched for gender; children of the Mongoloid race prevailed in the experimental group. Parents (or official representatives) of all participants signed an informed consent before the enrollment. The efficacy of vaccination was evaluated by active monitoring (telephone contacts with parents) and assessment of the incidence of influenza and acute respiratory viral infections (ARVIs) during the next 6 months. We calculated the efficacy index and efficacy coefficient. Data analysis was performed using the Statistica 6.0 software; differences were considered significant at p < 0.05. Results. Follow-up of study participants during 6 months after vaccination demonstrated significant differences in the incidence of ARVIs and influenza between the two groups: 7 cases among vaccinated children (2,3%) vs 21 cases among controls (7%) (p < 0.05). One child from the control group had two episodes of ARVI. Mean duration of influenza and ARVIs in the experimental group was 1.8 times lower than that in the control group. The efficacy index and efficacy coefficient, calculated with the consideration of influenza diagnosis confirmation by polymerase chain reaction, were 3% and 66.7%, respectively. Local and systemic reactions to vaccination were observed in 3 children, were transient, and disappeared after 2-3 days. Conclusion. The trivalent inactivated polymer-subunit vaccine Grippol® plus was safe and effective in children aged between 8 and 14 years.