Friday seminar: Effective or not? World’s first vaccination programme and the epidemiology of childhood infections in a developing society

By Michael Briga from University of Turku, Finland. Note the time: We start at 11.15.


Although vaccination is a crucial tool in efforts to combat infectious diseases, many vaccine-preventable diseases persist. Determining the effectiveness of vaccination programmes is key to inform public health practitioners and the general public, but vaccination programmes often go hand in hand with socio-demographic developments that can profoundly alter the infectious disease burden. Parsing the contributions of socio-demographic changes from that of vaccination itself  represents a challenge which we here attempt to address.

Theory predicts that effective vaccination programs will (i) decrease infectious disease burden, (ii) increase the age at infection, (iii) increase the time between epidemics, (iv) increase fade-outs, which all result from (v) decreased pathogen transmission. We here test these five predictions on the first vaccination programme in human history against the highly lethal childhood infection smallpox using a newly available database containing one hundred years of cause and age-specific mortality data across all of Finland in the 18th and 19th century. We compare smallpox epidemics both before and after vaccination and in order to capture the effects of long-term socio-demographic changes, we quantified the epidemic dynamics of two ‘control’ infections without vaccination, pertussis and measles.

For smallpox, we found support for all the theorized benefits of vaccination within a decade after the vaccine was first introduced. In contrast, during the same period, almost all epidemic dynamics of the childhood infections without vaccination, pertussis and measles, changed in the opposite direction. These results show that the first vaccination programme in human history was highly effective and contribute to the increasingly robust evidence on the benefits of vaccination, which will hopefully motivate the general population to make informed decisions on vaccinating children.

Michael Briga,
University of Turku, Finland

Published Jan. 27, 2020 2:37 PM - Last modified Mar. 8, 2021 10:22 AM