Based on the risk of international spread of poliovirus, the World Health Organization announced on January 7 that polio will continue to remain a Public Health Emergency of International Concern (PHEIC) for three months. The decision was taken based on the recommendation of the emergency committee under the international health regulations that assessed the situation last month. The committee arrived at the unanimous decision based on the “rising risk” of international spread of wild poliovirus type-1. Polio was declared as PHEIC in 2014 and has continued to remain one since then. There were 156 cases of wild polio type-1 cases in 2019 compared with 28 in 2018. With 128 cases, Pakistan accounted for the most number of cases, while Afghanistan reported 28 cases. Besides the four-fold increase in cases, there were instances of the wild type-1 virus getting exported from Pakistan to Iran and Afghanistan, as also on the spread from Afghanistan to Pakistan. In addition to the virus causing polio in children, it was found in the environment in Pakistan and, to a lesser extent, in Afghanistan. This is particularly a concern as the number of children not vaccinated in Afghanistan has been increasing. In 2018, a total of 8,60,000 children in Afghanistan did not receive polio vaccine due to security threats. The situation did not improve in 2019 and, as a result, a large cohort of children in the southern region of the country remains unprotected. Therefore, even other parts of the country that have been free of the virus in the past are at risk of outbreaks.
An equally disturbing development is on the outbreak of vaccine-derived poliovirus cases in 16 countries; in all, there were 249 vaccine-derived poliovirus cases in 2019. Surprisingly, of them, only 30 were in countries where vaccine-derived poliovirus is endemic. “The rapid emergence of multiple circulating vaccine-derived poliovirus type-2 strains in several countries is unprecedented and very concerning, and not yet fully understood,” the committee noted. But, not a single case of vaccine-derived poliovirus was reported from Afghanistan, while Pakistan had just 12 cases. In comparison, the number of cases in Angola was 86 and the Democratic Republic of the Congo was 63. While Nigeria reported 18 cases of vaccine-derived poliovirus, not a single case of wild poliovirus type-1 has been reported from the country for over three years; the last reported case was in August 2016. A country is said to have eradicated polio when no new case of wild poliovirus is reported for three successive years. Nigeria is all set to be declared as having eradicated polio this year, and in turn, the entire African region will become free of wild poliovirus.