COVID-19 has triggered a new century of vaccination and infection control for the benefit of all mankind

Modern safe vaccinations were pioneered in 1796 by Edward Jenner in England, when he noticed that milkmaids had beautiful complexions, clear of the blemishes from smallpox scars. This was attributed to their exposure to ‘cowpox’ in localised blisters, which seemed to protect them from the more severe and often fatal ‘smallpox’. In the twentieth century, the importance of immunity was emphasised by the very first Nobel Prize in Medicine, awarded to Emil Adolf von Bering who recognised the therapeutic role of antibodies in blood,1 using plasma from a recovered human (or horse) to protect and treat diphtheria, and eventually inventing the diphtheria vaccine in 1907. The first vaccines were simply made, being denatured protein extracts of live cultured bacteria, so there was no danger of causing the disease from the vaccination. Diphtheria-Pertussis-Tetanus (DPT) vaccine has long been available and is given to infants, making these three dreaded diseases of children uncommon in Western countries. My first personal experience with vaccination was as a 6-year-old (school grade 1) with my mother and 3-yearold brother attending the town hall in Kalgoorlie, Western Australia, for a mass polio vaccination administering the Salk vaccine. I remember that the vaccine was in a 50 ml multiple use bottle containing an estimated 25 dosages of 2 ml. The hall was pandemonium, with lines of people and numerous crying children. Hygiene in the stuffy, packed hall was less than ideal, the multiuse needles simply being soaked in alcohol for sterilisation between patients, becoming blunt and unsafe for use. But there had been at least a 12-month delay before the Salk vaccine could be used in Australia, as one of the early batches from Cutter Labs USA was withdrawn. The virus antigen made from cultured polio virus had not been sterilised adequately in 1955, resulting in more than 250 cases of actual polio in the USA. This caused the FDA to go on high alert, insisting on more stringent manufacturing and quality control procedures, followed by large-scale phase 1, 2 and 3 testing for all new vaccines. The concept is that, because vaccines are given to healthy people, a one-in-a-million incidence of severe side effects (or death) may be too much, even when preventing a dangerous disease such as polio or more recently COVID-19. Attenuated live polio vaccine replaced the Salk injected vaccine after 1960. Under the umbrella of the school vaccination programme, I received the new format whereby a drop of the pink vaccine was placed on a sugar cube and then eaten. The success of the new Sabin vaccine was its simplicity and oral format. After all, polio is an enterovirus, and I suppose family members could be infected with the live vaccine strain if schoolchildren experienced a very mild gastrointestinal illness at home. The live vaccination trivalent Sabin strain could cause overt polio in very few cases so that, as the actual wild-strain polio became extremely rare, vaccinationstrain polio became relatively more common. For that reason, most polio vaccinations are once again using an updated Sabin bivalent vaccine model, reducing the cases of vaccine-caused polio to near zero.2 In 1995 I was invited to Philadelphia by Dr Maurice Hilleman, who had developed many of the common vaccines in use today, most notably the Measles Mumps Rubella (MMR) vaccine. He used the unconventional source of his infected daughter to isolate the mumps virus in order to develop the vaccine. That visit opened my eyes to the many possibilities for producing vaccines, from chimeric attenuated virus to nasal inhalations and even the ‘holy grail’ of vaccines, that is in food such as transgenic bananas. Long before receiving a Nobel Prize in 2005 (for Helicobacter and Peptic Ulcers), I was awarded the Prince Mahidol medical prize in Thailand. This is the Asia