Recent insights into one of history’s most effective vaccination campaigns highlight critical lessons for expediting vaccine adoption today. This successful effort eradicated smallpox in Copenhagen during the early 1800s.

Smallpox, a devastating infectious disease, resulted in a mortality rate of 30% and left survivors with disfigurement and blindness, leading to an estimated 500 million deaths before its global eradication in 1980 through vaccination.

Copenhagen saw one of the earliest local triumphs over smallpox, achieving eradication in 1808 after claiming over 12,000 lives over fifty years.

The world’s first vaccine, developed by British physician Edward Jenner in 1796, quickly gained traction among Denmark’s medical and social elite, sparking “excited attention and anticipation,” as documented by leading physician Henrik Kalissen.

Doctors in Copenhagen swiftly sought smallpox vaccine supplies from Jenner in England. The inaugural recipient was a Danish judge’s child, followed by a bishop’s child. The vaccine proved remarkably effective, preventing transmission even among close contacts of infected individuals, including breastfeeding mothers, according to Calisen’s observations.

In response, the King of Denmark founded a Vaccine Commission in 1801, tasked with broadening the vaccine’s reach and meticulously tracking vaccination rates and smallpox outbreaks.

Researchers from Roskilde University analyzed these records, revealing that by 1810, 90% of Copenhagen’s children had been vaccinated, leading Denmark to rank as the highest in Europe for vaccination rates per capita.

Due to the rapid dissemination of the smallpox vaccine, the disease was eliminated from Copenhagen just seven years after the campaign’s initiation. “We will be free from one of the most destructive diseases known to us,” Calisen expressed in 1809.

Eilersen and his team identified key factors behind the high vaccination rates. Vaccines were offered free of charge to families in need, and many church leaders and school teachers actively promoted and administered the vaccines. The Vaccine Commission commended clergy who traversed the nation to disseminate knowledge about vaccinations, with one priest vaccinating nearly 2,000 children in just one year.

As smallpox cases dwindled, concerns arose about public apathy towards vaccination. To sustain high rates, the committee mandated that vaccination be a prerequisite for a child’s enrollment in church activities as of 1810.

While some resisted vaccinating their children, citing “ignorance and prejudice,” the broader public largely supported vaccination, Calisen noted. He acknowledged initial fears about vaccines but ultimately recognized their tremendous impact on public health and population growth.

Eilersen believes that the collaboration among Danish leaders fostered public trust and encouraged widespread vaccine acceptance. “Unified authorities, including government, medical institutions, and religious leaders, contributed to convincing a diverse population to embrace vaccination,” he stated.

Denmark continues to enjoy robust confidence in its governmental and health institutions, currently ranked first in public trust by Transparency International. In turn, this commitment has contributed to high childhood vaccination rates, with approximately 96% of Danish children vaccinated against diphtheria, tetanus, and pertussis, contrasting with only 80% in the United States, which ranks 28th in public trust levels.