In the scope of this paper, an analysis of the clinical trial results assessing the clinical and immunological efficacy of the effects of flavonoids on some indicators of immunity in children and adults is given.The aim of the study was to evaluate the effects of flavonoids on the cellular component of the immune system in children and adults with viral and viral-bacterial diseases by using meta-analysis and statistical analysis of the clinical findings.The analysis comprises 5 scientific sources with the results of controlled clinical trials involving 412 children and 15 sources involving 1493 adult patients during the period from 2003 to 2017. In analysis Student's t-test was applied.The data obtained indicate the efficacy of flavonoids in the treatment of viral and viral-bacterial diseases in children and adults. The administration of flavonoids (Proteflazid®, Immunoflazid®, Flavozid®) in the treatment of children with acute respiratory diseases and adults with HHV infection contributes to the normalization of cellular immunity indicators, the HHV infections symptom resolution, and the relapse rate reduction of genital herpes caused by HHV infection.Therapy with such medical products as Proteflazid®, Immunoflazid®, Flavozid® helps to improve the clinical status and normalize the cellular immunity indicators in patients who were administered a treatment course.