Expert Explains: How Poliovirus Is Similar (Or Different) To Coronavirus

In a world swamped by the current Covid-19 pandemic, it is easy to overlook the existence of other viruses that can cause serious illness. One of these viruses that has affected our lives since the days of Egyptian civilization is the poliovirus. Each year October 24 is marked as World Polio Day to celebrate the birth of Jonas Salk, the American researcher who developed the first polio vaccine in 1955.

Poliovirus is the simplest known human virus. It is very small at just 30 nanometers. In comparison, SARS-CoV-2 is a slightly larger virus at around 100 nanometers.

Poliovirus was first isolated in 1909 by Karl Landsteiner and Erwin Popper and the first human coronavirus was isolated in 1933 by Leland David Bushnell and Carl Alfred Brandley.

Poliovirus causes a crippling and potentially fatal disease called polio. The virus spreads from person to person and can infect a person’s spinal cord, causing paralysis. In about 25% of all people infected with polio, it causes very mild flu-like symptoms, including sore throat, fever, fatigue, nausea, headache, and stomach ache for about 2 to 5 days and they make a full recovery.

However, in a smaller proportion, infected people may develop other symptoms such as “pins and needles” or a tingling or tingling sensation in the arms and legs, meningitis, and paralysis of the arms and legs. Children under the age of five are most at risk of developing serious complications from poliovirus, which affects their quality of life.

Polio is very contagious and can easily spread from person to person – the R-naught value, that is, the number of people an infected person can infect for polio is 5 to 7. For Covid-19, the R-naught value is 1.4 to 3.9.

Poliovirus is spread by person-to-person contact, especially by the fecal-oral route. Poor hand hygiene, lack of access to safe drinking water, inadequate sewage systems are the most common reasons for the incidence and transmission of polio. However, in the 1950s, the first polio vaccine was invented by Jonas Salk. It was a very safe and effective inactivated polio vaccine given by injection.

Although very effective, at this time the availability of disposable syringes was scarce and the speed of vaccination was low. Another polio vaccine, invented by Albert Sabin in 1961, was called the oral polio vaccine (OPV). This was more easily administered to a large number of people with ease. A combination strategy was determined and mass administration began. Polio eradication is one of the most ambitious global health initiatives in history, and polio will only be the second human disease in history to be eradicated (the first was smallpox).

Today, the only places in the world where wild polio exists are Pakistan and Afghanistan. The successful use of this vaccine reduced the number of polio cases from 3.5 lakh in 1988 to 33 in 2018.

Because polio is highly contagious, no one is safe until everyone is vaccinated. Since the introduction of the Global Polio Eradication Initiative (GEPI) in 1988, the stringent efforts of the Department of Health and Family Welfare for the surveillance of wastewater samples for poliovirus and a robust immunization program as a public-private partnership with Rotary International have made this immunization program a great success. Since March 27, 2014, India has been declared polio free.

The science of vaccine development and our understanding of our immune system has improved dramatically since the development of the polio vaccine. In the field of vaccinology, researchers have been working for decades on the design and development of vaccines that are safer, more effective and less expensive.

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Various safe and effective Covid-19 vaccines have been developed across the world using conventional vaccine development technology as well as more modern advanced technology.

Designing a strategy, developing a vaccine, testing its safety and efficacy is a laborious, long and expensive process. However, during the time of Covid-19, vaccine developers had decades of data, abundant volunteers, and sufficient funding to study the effectiveness of different vaccines. Collaboration between scientists, regulatory agencies and vaccine manufacturers has paved the way for us to have multiple Covid-19 vaccines in such a short time.