Vaccine-derived polio spreads in Africa after defeat of wild virus

The Guardian ^ | 09/02/2020 | Peter Beaumont

[BenLurkin]

A new polio outbreak in Sudan has been linked to the oral polio vaccine that uses a weakened form of the virus.

...

WHO said two children in Sudan, one from South Darfur state and the other from Gadarif state, close to the border with Ethiopia and Eritrea, were paralysed in March and April. Both had been recently vaccinated against polio.

The WHO said initial outbreak investigations showed the cases were linked to a continuing vaccine-derived outbreak in Chad that was first detected last year and is now spreading in Chad and Cameroon.

While so-called vaccine-derived polio is a known risk, the emergence of these cases so soon after the announced eradication of wild polio in Africa is a setback.

At issue is the fact that the oral polio vaccine – preferred in some places because of its ease of delivery and the lack of need for sterile syringes – uses an attenuated or weakened version of polio.

When a child receives the oral vaccine, the weakened virus replicates in the intestine, encouraging the production of antibodies, and can be present in excreta. In an area where there are high enough levels of immunity in the population, this usually does not present a problem, even if sanitation is poor.

But in areas where there is both poor sanitation and a lack of general immunisation the virus can survive and circulate for months, mutating over time until it poses the same risk of paralysis-causing disease as wild polio.

Use of the oral polio vaccine was discontinued in the UK in 2004 and the US in 2000, and the UN agency advises that the use of the oral vaccine should be discontinued after polio is judged to be eradicated because of the risk of vaccine-derived outbreaks.

[TexasTransplant]

*** “I’ll be glad when 2020 is over” ***

I hope I survive it!