How a 19th century vaccine defeated smallpox in Denmark in just 7 years

A new look at one of the most successful vaccination campaigns in history, which quickly eradicated smallpox in Copenhagen in the early 1800s, has revealed possible lessons for boosting vaccine uptake in the modern era.

Smallpox was a devastating disease that killed three out of 10 people infected and left many others with disfiguring scars or blindness. In total, it claimed an estimated 500 million lives before it was finally eradicated in 1980 by a worldwide vaccination campaign.

However, one of the first local eradications of the disease was achieved as early as 1808 in Copenhagen, where smallpox had killed over 12,000 people in the previous half century.

The smallpox vaccine, the first ever vaccine, was invented by the English physician Edward Jenner in 1796. The news quickly spread to the Danish medical community and social elite, creating “excited attention and anticipation,” wrote Henrich Callisen, a leading Danish physician at the time.

Doctors in Copenhagen soon began ordering the smallpox vaccine from Jenner in England. The first recipient was the child of a Danish judge, soon followed by the child of a bishop. The vaccine appeared to be surprisingly effective, allowing recipients to share beds with family members who had active smallpox, wear their clothes or even breastfeed from infected mothers and still not catch the disease, Callisen wrote.

Based on these reports, the Danish king ordered the establishment of a vaccination commission in 1801. She was in charge of spreading the smallpox vaccine as widely as possible and keeping detailed records of vaccinations and smallpox cases.

Andreas Eilersen at Roskilde University in Denmark and colleagues analyzed these records to examine the effects of vaccine introduction on smallpox incidence. They found that by 1810, 90 percent of children in Copenhagen were receiving the vaccine, making Denmark the most vaccinated country per capita in Europe.

Thanks to this rapid adoption of the vaccine, smallpox disappeared from Copenhagen just seven years after the vaccination campaign began. “[We] will be freed from one of the most terrible and destructive diseases we know,” Callisen wrote in 1809.

Eilersen and his colleagues identified several factors that contributed to this high vaccination rate. First, the vaccine was offered free to people who could not afford it. Second, many church leaders and school teachers agreed to support and administer the vaccine, in addition to medical professionals. In its annual reports, the vaccine commission praised a number of priests who traveled the country to spread information about the vaccine and administer it. One priest, for example, gave the vaccine to 1,981 children in a single year.

When smallpox subsided, the commission began to worry that people would forget how diabolical it was and be content to vaccinate their children. In 1810, in an effort to maintain vaccination rates, she decided to make the vaccine semi-mandatory by requiring it as a condition of church confirmation of children.

Some people refused to have their children vaccinated, which the commission attributed to “ignorance and prejudice”. However, the vast majority of people accepted it, Callisen wrote. He admitted that he was initially apprehensive about the vaccine when it first arrived, but said he was “fully convinced of the beneficial effect of vaccination on human welfare and happiness and on increasing population and national strength.”

Danish leaders have succeeded in instilling this widespread confidence in the new vaccine by presenting a united front, Eilersen believes. “We basically had a bunch of different authorities—the government, the medical establishment, and the church—all agreeing on what to do,” he says. “When everyone worked together like that, it helped convince the broader population that wasn’t part of that elite group to take the vaccine.”

In fact, Denmark continues to have high levels of trust in its government and medical authorities. That currently is in first place in terms of residents’ trust in public institutions according to Transparency International, a group that monitors perceived corruption in 180 countries. This may explain the continued high vaccination coverage of children. For example, Fr 96 percent of children in Denmark today receive vaccines against diphtheria, tetanus and whooping cough, compared to only 80 percent in the US, which ranks 28th in terms of trust in the public sector.

topics:

• vaccines/
• infectious diseases