Polio Outbreak Ends in Somalia
The Director of Polio Eradication for World Health Organization (WHO) Eastern Mediterranean Region declared Somalia’s outbreak of circulating vaccine-derived poliovirus type 3 (cVDPV3) closed.
According to an article published by the Global Polio Eradication Initiative (GPEI) on April 14, 2021, Dr. Hamid Jafari confirmed a full twenty-eight months have passed since this strain of polio was last detected in Somalia.
Poliomyelitis (polio) is a highly infectious viral disease that primarily affects children five years of age and under. There are three strains of wild poliovirus (type 1, type 2, and type 3).
During the 2018 outbreak, seven children were paralyzed by the type 3 strain.
And sewage samples regularly monitored for poliovirus tested positive for cVDPV3 a dozen times, beginning March 2018.
The good news is after extensive disease surveillance measures, no cVDPV3 has been identified since September 2018, when the last child developed paralysis.
‘Closing a polio outbreak is a formal process steered by a detailed checklist of surveillance indicators that must be met to show that the virus is not just hiding in a far-flung pocket but has truly disappeared,’ commented Dr. Jafari.
‘Sewage runoff is tested for the virus, and health workers and community members actively search for paralysis in children and then investigate any paralysis they do find to rule out polio. Accessing hard-to-reach communities is a challenge in Somalia, but a vital aspect of this work.’
The 2018 cVDPV3 outbreak was part of a 2-strain polio outbreak in Somalia at that time, along with circulating vaccine-derived poliovirus type 2.
Both strains emerge and paralyze children in under-immunized populations; places, where not enough children have consistently, had access to polio vaccines.
The cVDPV2 outbreak continues to paralyze children, and environmental samples – sewage water – consistently show that the virus is moving through Somali communities.
For the polio program, the presence of cVDPV2 samples and the absence of cVDPV3 samples is bittersweet, says Dr. Jafari. It demonstrates the sensitivity of our testing so that we can be confident cVDPV3 is no longer a threat to Somali children – but it makes clear that the threat of paralytic polio still looms.’
The end of Somalia’s cVDPV3 outbreak shows what can be achieved with high-quality vaccination campaigns, on-the-ground leadership, and sensitive surveillance measures. There are several polio vaccines available in various countries as of April 17, 2021.
And the WHO Prequalification program issued an Emergency Use Listing recommendation for the nOPV2 vaccine on November 13, 2020.
However, across the WHO’s African Region, polio cases are on the rise. On April 13, 2021, the GPEI reported ten countries confirmed new polio cases.
This updated WHO map shows the latest number of WPV1 and cVDPV cases in each affected country.
In the early 1950s, before polio vaccines were available, polio outbreaks caused more than 15,000 cases of paralysis each year, says the U.S. CDC.
Following the introduction of vaccines, specifically, the trivalent inactivated poliovirus vaccine (IPV) in 1955 and the trivalent oral poliovirus vaccine in 1963, the number of polio cases fell rapidly to less than 100 in the 1960s, and fewer than 10 in the 1970s, says the CDC.
Since 2000, the IPV is most often given in the USA during 2021. Most infants and children should receive four doses of IPV at ages 2, 4, 6–18 months, and 4–6 years, suggests the CDC.
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