Researchers who have looked at trends of vaccine acceptance around the world have found that, overall, people’s trust in vaccine safety and effectiveness has been on the rise over the past few years.

However, they have also expressed concern that the race for a COVID-19 vaccine may have triggered more hesitancy among certain groups.

Speaking at this year’s WIRED Health:Tech conference, Prof. Heidi Larson, from the London School of Hygiene & Tropical Medicine, in the United Kingdom, noted that “Because of the hyper-uncertainty and the whole environment of trust and distrust around the COVID vaccine, there are groups that have gotten together to resist” upcoming vaccination.

Many may now be wondering why researchers are so keen on vaccines — and whether vaccines have really achieved much for public health.

So, in this Special Feature, we look at some key moments in vaccine history and how vaccines have revolutionized public healthcare.

The ancient practice of ‘variolation’

Vaccines work by exposing the immune system to a very small amount of a virus or “information” about a virus — enough to “teach” it to recognize and react to that pathogen.

The idea of exposing the body to a virus in a controlled way to “train” it to prevent infection is by no means a modern conception.

Already in the 1500s, Chinese and Indian physicians practiced inoculation against the variola virus, which causes smallpox.

Some accounts from China in the 1600s suggest that doctors attempted the inoculation by grinding up smallpox scabs and blowing them into the patient’s nose through a silver tube.

In Europe, inoculation against smallpox, a process known as “variolation,” was introduced and popularized by Lady Mary Wortley Montagu in the early 18th century.

Lady Wortley Montagu was the wife of the British ambassador to the Ottoman Empire. From 1716–1718 she travelled across Europe to Constantinople, present-day İstanbul, where she learned about variolation.

She was so impressed by the evidence of its effectiveness that she submitted her own son for inoculation against the smallpox virus while in Constantinople and continued to advocate for the procedure on her return to Britain.