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Polio: an old enemy that threatens to return

In his book “Jonas Salk, a Life”, Charlotte DeCroes Jacobs describes the summer of 1916 in New York. The parents of families trembled with fear at the advent of heat, for they knew that it was the time of outbreaks of poliomyelitis or infantile paralysis. Hundreds of children randomly developed a disease that in two or three days led to permanent paralysis of one or more arms or legs, and some others died of suffocation because the infection compromised the breathing center in the nervous system.

That terror of summers also happened in other cities in many other countries. I remember a lot that in my childhood, my late mother refused to take the family to the beach in Lima, because she assured that she had caught the disease there. polio a familiar. That may be why I prefer the mountains to the beaches for my vacations.

the injectable vaccine

The history of the vaccine polio It reflects the state of science in the 1950s and depicts the struggle between the monumental egos of two scientists, whose vaccines have been used until now: Jonas Salk and Albert Sabin.

During the first years of that decade, the young researcher Salk developed a vaccine injectable that used inactivated virus. At the same time, Dr. Sabin was also developing a vaccine that, unlike Salk’s, used live attenuated viruses and had the advantage of being able to be administered by mouth.

Initial experiments with disabled children and his own family, conducted in late 1952, enabled Dr. Salk to announce on a television show on March 25, 1953 that his vaccine it was effective and safe, and that the largest clinical study in the history of medicine was being prepared.

This study began on April 26, 1954, and was composed of two parallel experiments. The first, carried out on 750,000 children in the first, second and third year of primary school, drew them to receive the vaccine or a placebo. Neither the parents nor the teachers nor the researchers knew which injection the children were receiving. The objective was to verify the effectiveness of the vaccinecomparing the cases of polio in vaccinated children and those who received the placebo.

“The history of the polio vaccine reflects the state of science in the 1950s and depicts the struggle of scientists Jonas Salk and Albert Sabin.”

The second study administered the vaccine to 400,000 children in the second year of primary school, comparing them with 725,000 children in the first and second year of primary school who did not receive the vaccine and served as a control group.

The newspapers of the time report the enormous interest of parents, who struggled to enroll their children in the study, the sight of hundreds of paralyzed children in wheelchairs or using metal supports on their legs was the only education they needed receive to want to participate.

The study announced on April 12, 1955 caused millions of people, who had been waiting for the news on their radios, to take to the streets to celebrate, while the bells of all the churches tolled in celebration of the good news.

The vaccine (IPV) was approved that same day by the Government and the next day the most successful vaccination campaign in US history began. By 1957, annual cases fell from 58,000 to 5,600, and in 1961 only 161 cases. Salk never patented the vaccine and in a 1955 interview, when asked who owned the IPV vaccine patent, he replied: “Well, people would say I. There is no patent. Could the sun be patented?

oral vaccine

Around the same time, Albert Sabin, who greatly disliked Jonas Salk, developed his oral vaccine, which was studied in 20,000 children in 1958, in 10 million children in 1959 in the Soviet Union, and in more than 110,000 children between 1958 and 1959 in Czechoslovakia, demonstrating that it was safe and effective.

The oral vaccine (OPV) began to be used in Hungary in December 1959 and in the former Czechoslovakia in the early 1960s, which became the first country to eradicate polio in the world. Cuba began using it in 1962 and from then on, due to its ease of administration, OPV was the preferred vaccine, especially in poor countries.

While it is true that IPV protects the vaccinated child from the disease, it does not prevent an infected child from shedding the virus in their feces. For its part, OPV not only protects the child from the disease, but is also capable of preventing the virus from being eliminated through the feces, making it ideal for preventing outbreaks.

Unfortunately, in regions with low vaccination coverage, the attenuated vaccine virus can circulate among unvaccinated children, and mutate into a strain called circulating vaccine-derived poliovirus (cVDPV), which is capable of causing paralysis.

Currently, the original or wild virus only circulates in Pakistan and Afghanistan, while cVDPV cases in the world tripled between 2018 and 2019, and between 2019 and 2020. Between January 2020 and April 2022, 33 Countries reported nearly 1,900 cases of cVDPV paralysis.


Childhood vaccination programs, very successful in Peru in the past, began to decline before the pandemic, and suffered a severe deterioration during it.

Peru uses a combination of injectable and oral vaccines. It is urgent that the Minsa reinforce the childhood vaccination program, since it would be terrible if, due to the low vaccination coverage, the first case of polio in the Americas appeared in Peru.

Source: Elcomercio

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