As the world is starting to undertake an unprecedented vaccination effort to control the current pandemic, it might be useful to look at other historic vaccination programs.

Smallpox

Attempts at smallpox vaccination have gone on for many centuries using material from the smallpox pustules of people with mild cases or from cowpox pustules to inoculate healthy persons. The most widely recorded example occurred in 1768 when Catherine the Great, Empress of Russia, allowed a Scottish physician to inoculate (vaccinate) her. She developed a mild case, recovered after two weeks, and then had fluid from her own pustules used to inoculate her son and members of her court. After Catherine’s heroic action, inoculation became quickly accepted, and by 1780 two million inoculations were administered in the Russian Empire. An alternative and improved method of vaccination was introduced in 1796 by Edward Jenner, who noted that milkmaids who had been infected with cowpox, a skin infection caused by a virus related to the smallpox virus, did not get smallpox. He removed fluid from the cowpox pustules of a young dairymaid and inoculated an eight-year old boy. The child developed a mild fever but recovered – a successful but highly unethical experiment.

While the final word is not in, it would appear that SARS-CoV-2, the coronavirus responsible for the current COVID-19 pandemic possibly originated in bats and then spread to humans via infected intermediate host animals in live food markets in China. Human-to-human transmission is primarily through infected airway droplets and aerosols but may also occur through contact with contaminated surfaces. There have been rare instances of coronavirus infection in various non-human species, including tigers, lions, hamsters, monkeys, and ferrets. In April, 2020 there was a COVID-19 outbreak at the Bronx Zoo affecting five tigers and three lions with probable virus transmission from an infected but asymptomatic zookeeper. The big cats had a mild cough and loss of appetite, but all made a quick recovery

As we learn more about the epidemiology of COVID-19, it appears that the main source of transmission is through virus-carrying droplets and airborne aerosols. However, direct person-to-person contact is also thought to play a role, which has led to recommendations for masking, social distancing, and hand hygiene. These recommendations are having a major impact on human behavior and threaten to relegate the ubiquitous handshake to the waste (or hand) basket of history.

Shaking hands has a long history as one of the most recognized forms of non-verbal human communication, probably first recorded in