(Bloomberg) -- Zimbabwe began a polio inoculation campaign after an outbreak of the virus that can cause the crippling disease, the Ministry of Health said. 

Vaccine-derived poliovirus type 2 has been detected in three suburbs in the capital Harare, Health Minister Douglas Mombeshora said in an emailed statement on Wednesday. 

The rare strain stems from mutated live poliovirus, which is contained in the oral vaccine. In severely under-immunized populations, the virus can then pass between people who have not received the vaccine, allowing it to continue to change for a long period of time, and potentially regain its ability to paralyze.

Re-emergence of the potentially deadly virus that spreads via the fecal-oral route has been seen in various countries, including in the US. That’s partly because global pediatric immunization has struggled to regain levels reached prior to the Covid-19 pandemic. 

Zimbabwe is offering adults that live in the epicenter of the outbreak vaccines and has rolled out mass immunization efforts in schools across the country, part of an incident management system that has been activated to ensure a coordinated response. If a population is fully immunized, they will be protected against both vaccine-derived and wild polioviruses, according to the World Health Organization.

The government is seeking financial and technical support from the WHO and other international partners, the minister said. No deaths have been recorded so far.

(Updates with explanation of vaccine-derived poliovirus in third paragrpah)

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