Two Strains of Polio are Gone, but the End of the Disease is Still Far Off

In October, health officials announced that 2 of the 3 strains of wild polio virus have officially been eliminated. The strain that the Global Certification Commission for the Eradication of Poliovirus declared eliminated recently was Type 3 wild polio virus, the last case of which was seen in Nigeria in 2012. Type 2 was declared eliminated in 2015; the last case was detected in India in 1999. Type 1, the only wild strain left, circulates only in Pakistan and Afghanistan. Although the world is closer to eradication, the effort has taken longer than anticipated, leaving two major obstacles. First, millions of families have not received the vaccine drops because of fallacies that the vaccine is a plot to sterilize Muslim girls or do other harm. Second, viruses used in the oral vaccine itself have mutated into a form that can be passed on in diapers and sewage, and can paralyze unvaccinated children. That has contributed to fear of the oral vaccine, even though full vaccination is the only protection against such mutant viruses. Just in the last two months, cases of paralysis caused by mutant vaccine viruses have been reported in the Philippines, Zambia, Togo and Chad. Stopping such outbreaks typically requires vaccinating hundreds of thousands of children with both the injectable vaccine, which contains killed virus that cannot mutate, and the oral vaccine. Although most of those outbreaks have been small and eventually were contained, more children are now paralyzed. “We don’t need to create a new problem,” Mr. Zaffran said, who is the director of polio eradication at the World Health Organization. Luckily, however, novel versions of Type 1 and Type 3 vaccines should follow in another couple of years.

- Sophia Gamboa

Link: https://www.nytimes.com/2019/10/23/health/polio-strain-eradication.html?searchResultPosition=7