Edward Jenner is known as the scientist who has saved the most lives in the history of humanity. Smallpox claimed the lives of more than 60 million people in Europe alone in the 18th century, and 300 million in the 20th century.
The 8-year-old boy on whom the first smallpox vaccine was tested has not gone down in medical history with such glory, but he was the real hero. His name was James Phillips, and he is said to have been Jenner’s nephew (or the son of his gardener).
On May 14, 1796, the scientist decided to inoculate him (in the shoulder, with a lancet) with some matter that he obtained from a person who had cowpox pustules.
The boy developed a mild fever that disappeared within a few days. A few months later, Jenner implemented the definitive test to prevent smallpox. He inoculated the boy again, but this time with material extracted from the pustules of a person with human smallpox, to see if he would develop the disease. The results proved him right and the boy did not contract the disease and did not die.
So, Jenner formulated, in a rudimentary way, the germ of the first modern vaccine. A few years later, in 1803, King Charles IV (whose daughter had died of smallpox) financed the Royal Philanthropic Vaccine Expedition, also known as the Balmis Expedition, to bring the vaccine to America and Asia. Led by the Spanish doctor Francisco Javier Balmis, with the help of his colleague José Salvany and the nurse Isabel Zendalthe mission achieved a technical feat: keeping the vaccine active during transoceanic voyages. It was the first non-profit global health expedition, as well as a 100% Spanish initiative.
The 22 angels
His idea, which today would be considered inhumane and could not be carried out, was that 22 children living in orphanages carried the exudate from smallpox pustules on their arms.
At that time, the way to keep the vaccine active was to inoculate it in healthy people and transmit it between individuals, applying it from pustule liquid from arm to arm. It needed people who had not suffered from smallpox or been vaccinated so as not to alter the immune process. This feat is considered a milestone in the history of Medicine, not only for its success and novelty, but also because they achieved establish the vaccine in the new territories.
Over the centuries, the inoculation system improved. It was also seen that the virus from which the smallpox vaccine was derived (‘Vaccinia’ virus) could be maintained in animals. Due to the rudimentary nature of the period, the process was not traceable and the original cowpox virus was lost and replaced by other vaccine strains.
It would not be until 1948, with the creation of the World Health Organization (WHO) that the decision was made to carry out a new global vaccination campaign for the eradication of smallpox, something that was officially achieved in 1980.
“It was tested with different strains and the one that worked best was a virus called MVA (Modified Vaccinia Ankara). MVA was developed through a process of cultivation and adaptation to chicken cells from the Vaccinia Ankara Virus strain, and It was used clinically to prevent unwanted side effects of smallpox vaccination.. By adapting to growth in avian cells, MVA lost the ability to replicate in mammalian hosts,” he explains. Stanislaus Nistal, virologist and professor of Microbiology at the San Pablo CEU University in Madrid.
“It is, to summarise, an improved version of the cowpox virus that was used in the Balmis Expedition,” he adds, and explains that “it is a very useful vector because it is highly immunogenic and does not produce productive infection in the body, since it only replicates in the area where it is inoculated.”
There are only two places in the world where the eradicated smallpox virus is kept: the Center for Disease Control (CDC) in Atlanta and the National Research Center for Virology and Biotechnology in Koltsovo, Russia.
And that same vaccine, MVA is the one currently being used against other poxviruses (such as monkeypox)With the eradication of smallpox, the production of MVA vaccines became of no interest and only the pharmaceutical company Babarian Nordic continues to operate its large-scale production capacity today.
Nothing new under the sun
Knowing some of the fundamentals of epidemiology is the key to putting the current health emergency situation in its place. “Before talking about geographic containment strategies, mass vaccination, transmission patterns, etc., we must look at the fundamentals because The entire theoretical framework revolves around smallpox, measles, plague and cholera.explains Adrian H. Aguinagalde, specialist in Preventive Medicine and Public Health and director of the Public Health Observatory of Cantabria, in an interesting thread on the social network X.
“There has been contact with poxviruses for centuries, it is not something new like SARS-CoV-2 was. One of the problems is that Many people have learned about virology and immunology with Covid, and they use the same parameters for other viruses,” he explains to this newspaper. Rafael Toledo, Professor of Parasitology at the University of Valencia.
“The first hypothesis that must be ruled out is that there may be airborne transmission (through aerosols) of Mpox,” he said, referring to some voices that have been raised in the scientific community that explain with this argument the high rate of infections among children in the affected areas of Africa.
“Beyond immunological or sociodemographic connotations, pediculosis (lice) is also more prevalent in children, without this implying transmission by aerosols. It is easier to think that children’s games and gregarious habits justify these differences in directly transmitted diseases,” he explains.
There is no reason to believe that, with current containment strategies, the resurgence of Mpox could pose a threat to the West.