For small friends before 2016, sugar pills can be counted as childhood memories along with gourd babies, jumping candy, and contra.
A small sugar pill, with a sweet milk taste, usually want to cry when you see the injection doctor, when you take out the sugar pill has become particularly kind.
(Source network, intrusion and deletion)
As a child, I always thought that sugar pills were a comforting reward for injections, but when I grew up, I learned that it was also a vaccine and saved the lives of thousands of children.
People are generally susceptible to poliovirus
The sugar pills that carry our childhood memories are actually oral poliomyelitis attenuated live vaccine (OPV).
Poliomyelitis (Polio, Polio, referred to as polio), commonly known as "polio", is an acute infectious disease caused by polio type I, type II, and type III viruses, mostly occurring in children aged 6 months to 5 years.
Most patients with poliovirus infection present with latent infection, or mild clinical symptoms, respiratory and gastrointestinal symptoms, and neurological symptoms such as neck rigidity, but some patients will have severe clinical symptoms after infection, resulting in muscle paralysis, leaving lifelong disability or even death.
(Limb disability caused by polio is irreversible / Source: Figureworm Creative)
Humans are the only natural reservoir of poliovirus, latent infections and mild paralysis patients are the main sources of infection of the disease, and polio is mainly transmitted by fecal-oral infection.
The virus is excreted mainly through the patient's nasopharynx in the early stages of infection, so it can be transmitted by droplets, but for a shorter time. As the course of the disease progresses, the virus is excreted from the feces, which can be poisoned for months and spread through contaminated water, food, and daily necessities.
Populations are generally susceptible to poliovirus, but lasting immunity is acquired and specific after infection, so polio vaccination is the safest and most effective means of preventing, controlling and eradicating poliovirus. But more than a century has elapsed since the polio epidemic to vaccination.
The birth of sugar pills
In 1793, the British pediatrician Underwood made the first scientific description of polio; in 1840, the German surgeon Heine first made a critical report on its clinical manifestations.
Because the virus was not successfully isolated at that time, vaccine development has been slow. It was not until 1948 that a team at Boston Children's Hospital, led by John Franklin Enders, successfully cultivated poliovirus in the laboratory and discovered three serotypes of poliovirus.
Enders and his colleagues also received the 1954 Nobel Prize in Physiology or Medicine for this contribution. These research results have promoted the development of virology as a whole, and fundamentally provide an effective means for the development of polio vaccine.
In 1952, the American virologist Saul invented a safe and effective injectable vaccine, which began to be used in 1955; in 1957, the American microbiologist Sabine invented an oral vaccine, which began to be widely used in the 1960s.
Under the leadership of Academician Gu Fangzhou, China also successfully developed a live attenuated vaccine for polio in 1960. To eradicate polio, it must be widely covered so that children in rural areas can also receive live vaccines. However, live vaccines in liquid dosage forms need to be preserved at low temperatures and are not convenient for promotion in rural areas.
(Father of "China Polio Vaccine", Gu Fangzhou/Source Network, invasion and deletion)
After repeated exploration and experiments, Gu Fangzhou's team used milk powder, cream, glucose and other auxiliaries to roll the liquid vaccine into the sugar, and since then the "sugar pill" vaccine that has accompanied generations of Chinese has been born. Since 1965, the polio pill vaccine has been rolled out nationwide.
Improvement of polio vaccine
The effect of sugar pill vaccine is undoubtedly very significant, in the 1960s, the number of annual incidence reports of polio in China was 10,000 to 43,000 cases, and in 1964 it was the peak, with an annual incidence of 43,156 cases and an incidence rate of 6.21/100,000.
Since the nationwide roll-out of the sugar pill vaccine in 1965, the incidence of polio has decreased significantly. In 1988, the World Health Organization (WHO) began a global polio eradication campaign, and through mass vaccination of live oral polio vaccine, the global incidence of polio was reduced by more than 99%, of which the number of cases of native poliovirus (WPV) fell from 350 000 in 1988 to 33 in 2018.
THE WHO achieved polio-free targets in 1994, 2000, 2002 and 2014 respectively in the Americas, Western Pacific, Europe and South-East Asia.
Currently, only three countries, Pakistan, Afghanistan and Nigeria, have not interrupted indigenous poliovirus transmission. Polio has become the second infectious disease that has been basically eliminated by humans after smallpox.
Sugar pill vaccine is not only convenient to take, but also has an important advantage, that is, after taking the virus can continue to replicate in the intestine and excrete out of the body, the surrounding environment contact population can also obtain a certain degree of immunity, can achieve herd immunity.
However, it also carries a number of risks: in rare cases, oral live attenuated vaccines, after being excreted from the body through feces, have the potential to regain their virulence in the external environment, infecting other susceptible people, namely Vaccine-associated Paralytic Poliomyelitis (VAPP) and vaccine-derived Poliovirus (VDPV) Cases.
Although the probability is low, the risk cannot be ignored, and falling on a family can lead to tragedy.
In 2001, the WHO estimated the global burden of disease caused by VAPP, estimating that countries worldwide using live attenuated oral polio vaccines will experience 250-500 cases of VAPP per year, or 2-4 cases of VAPP per year per 1 million births.
In this regard, the Global Polio Eradication Initiative (GPEI) adjusted the polio vaccine immunization strategy in April 2016 to convert trivalent oral polio vaccine (OPV) into a safer bivalent oral polio vaccine (bOPV), and China also implemented a new polio vaccine immunization strategy from May 1, 2016, stopping trivalent live attenuated polio vaccine (sugar pills) and replacing trivalent live attenuated polio vaccine with divalent live attenuated polio vaccine.
(Although the live-attenuated vaccine for divalent polio is still oral, it is in the form of drops.)
/Image Source: Figureworm Creative)
Since then, this sugar pill vaccine, which has brought good memories to generations, has also officially withdrawn from the historical stage.
Edit: Dr. Spring Rain
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