Аннотация:The results of an analysis of the frequency of viral pandemics from 2008 to 2019 are presented, including statistics onEbola haemorrhagic fever, influenza AH1N1, AH7N9 influenza, MERS-CoV coronavirus, and HIV-1 infected patients in theRussian Federation from 1996 to 2019 (23–24 solar activity cycles) with solar radiation intensity at a wavelength of ~λ315 nm,representing the boundary between the UVB (280–315 nm) and UVA (315–400 nm) ranges, as well as the boundary of therelative spectral bactericidal efficiency curve (205–315 nm). A close relationship has been established between viral pandemicsand HIV-infected patients (a total of ~ 100,000 people) with a change in intensity ~λ315 nm (r ~ 0.85) in solar activity cycles.A conclusion has been made about the virulent effect of solar radiation ~ 315 nm on the development of viral pandemics.