A new study conducted by the Finnish Institute for Health and Welfare (THL) reveals the remarkable success of Finland's chickenpox (varicella) vaccination program. The research, presented today, indicates a drastic reduction in chickenpox-related healthcare visits in children under 12 years old, following the initiation of a comprehensive vaccination campaign.
The study, based on national primary healthcare registry data, demonstrates that the implementation of a two-dose chickenpox vaccination program for all uninfected children under 12 years old led to a reduction of over 95% in healthcare center visits for children in this age group in 2022 compared to the pre-vaccination era.
Notably, cases of chickenpox in unvaccinated infants under 1 year old also decreased by 87%, highlighting the effectiveness of the vaccination in providing herd immunity.
Finland launched its chickenpox vaccination program in September 2017. The program includes vaccine doses administered at 18 months and 6 years of age. Additionally, in the first year, extensive catch-up vaccinations were carried out, providing vaccine coverage for all children under 12 who had not previously contracted chickenpox.
"Prior to the vaccination program, 3-year-olds alone accounted for over a thousand annual chickenpox cases necessitating contact with primary healthcare. In recent years, these cases have reduced to just a few dozen annually," explained Dr. Heini Salo, Senior Researcher at THL.
Dr. Salo emphasized that while most chickenpox cases in young children do not require medical attention, it is likely that home-managed cases have decreased correspondingly as the overall virus circulation declined.
Despite the program's success, more than one in ten children remains unvaccinated. "The accumulation of susceptible individuals in the population means that chickenpox epidemics are likely to occur in the future," warned Dr. Salo. Unvaccinated children are at risk of contracting chickenpox as adults, especially during international travel. In adults, chickenpox can lead to more severe complications, necessitating medical attention and medication.
Finland pioneered its national chickenpox vaccination program, administering the first year's vaccinations to a quarter of a million children. Between 2017 and 2022, 85-87% of children received their first vaccine dose. Information on the second dose's coverage is available only for those born in 2016, reaching 58% in 2022.
Although the catch-up vaccinations were met with positive response, there is room for improvement. "Currently, more than one in ten individuals in every age group remain unvaccinated. Encouraging higher vaccination rates is essential to prevent potential outbreaks and protect the population from this preventable disease," concluded Dr. Salo.
The study underscores the importance of ongoing efforts to promote vaccination awareness, ensuring that all eligible individuals receive the necessary doses to create robust community immunity against chickenpox.