The number of chickenpox cases in children in Finland fell rapidly after the launch of the vaccination program

Finland was the first Nordic country to start a chickenpox vaccination program

Peer-Reviewed Publication

FINNISH INSTITUTE FOR HEALTH AND WELFARE

A recent study by the Finnish Institute for Health and Welfare (THL) reveals that a two-dose varicella vaccination programme to all children under the age of 12 who had not had chickenpox reduced the number of health centre appointments related to the disease significantly and fast in all age groups. The number of health centre appointments of children under the age of 12 decreased by more than 95% in 2022 compared with the time before the vaccinations. The number of chickenpox cases among unvaccinated children under the age of one also decreased by 87%, which suggests herd protection of the vaccinations. 

The varicella vaccination programme was launched in Finland in September 2017. The varicella vaccination programme includes doses at the ages of 18 months and 6 years. In addition, extensive so-called catch-up vaccinations were carried out during the first year, offering the vaccine to all those under the age of 12 who had not had chickenpox. 

“For example, while 3-year-olds had more than 1,000 cases of chickenpox requiring contact with primary healthcare every year before the vaccination programme, there have been only a few dozen cases per year in the past few years,” says Heini Salo, Senior Researcher at THL. 

“It should also be noted that the majority of young children's chickenpox cases do not require contact with healthcare. However, it is likely that, as the circulation of the virus has decreased, the number of chickenpox cases treated at home has also decreased,” Salo continues.  

Finland was the first Nordic country to start a chickenpox vaccination programme

Finland was the first Nordic country to start a chickenpox vaccination programme, and the vaccinations for all children under the age of 12 who had not had chickenpox were exceptionally extensive. In the first year of the vaccination programme, a quarter of a million children were vaccinated. 

Between 2017 and 2022, 85–87% of children received the first vaccine dose. Information on the coverage of the second dose is available only on those born in 2016. It was 58% in 2022. 

The catch-up vaccinations were also well accepted. Based on previous studies, it is known that 23% of 5–9-year-olds, for example, had not had chickenpox. However, the vaccination coverage in this age group was 33%, which was clearly higher than expected. 

There is still room for improvement in the coverage of chickenpox vaccinations. 

“At the moment, more than one in ten children in all the age groups do not get vaccinated. The accumulation of people susceptible to chickenpox in the population means that chickenpox epidemics are likely to occur in the future," Salo says. 

“Children who are not vaccinated may catch chickenpox as adults when travelling abroad, for example. Chickenpox is significantly more serious in adults than in children and practically always leads to a doctor's appointment and medication.” 

The study was carried out by examining the national register data in primary healthcare. 

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JOURNAL

Vaccine

DOI

10.1016/j.vaccine.2023.09.024 

ARTICLE TITLE

Decline in varicella cases contacting primary health care after introduction of varicella vaccination in Finland – A population-based register study

ARTICLE PUBLICATION DATE

17-Oct-2023