Final round of polio vaccination starts this weekend

The final round of mass polio vaccinations will start today and go on until next week on Wednesday.

The exercise is in response to the outbreak of vaccine-derived polio, which has a total of 16 cases reported.

Eight of the cases have already been confirmed while the other eight suspected cases are being processes at the Kenya Medical Research Institute.

This is the worst outbreak of the vaccine-derived polio in the country.

“Polio vaccination campaign will take place in seven high-risk counties namely, Kiambu, Kajiado, Machakos, Kitui, Lamu, Tana River, Nairobi, Garissa, Mandera and Wajir,” Public Health PS Mary Muthoni said.

According to the ministry, the wild polio, the virus which circulates naturally in the environment, was eliminated in Kenya in 1984.

The current outbreak is linked to vaccine-derived strains of the virus. 

On extremely rare occasions, the weakened virus in the oral vaccine, when shed through stool, can infect an unvaccinated person and regain strength, becoming just as dangerous as the original virus.

“All cases have been reported in Garissa county in Hagadera and Daadab Refugee camps,”  Dr Emmanuel Okunga, head of the division of disease surveillance and response, told the media last month.

The cases sequenced so far have been traced to Somalia, where the infected refugee children came from.

The first cases were reported in May, rising to six in July.

In response, the Ministry vaccinated 1.9 million children in Kiambu, Kajiado, Garissa and Nairobi counties between August 24  and 28.

The second round took place in October in 10 high-risk counties namely, Mandera, Wajir, Tana River, Lamu, Kitui, Machakos, Kiambu, Kajiado, Nairobi and Garissa, targeting 3,119,158 children.

Muthoni said all children under 15 years in all refugee camps in Garissa as well Fafi and Daadab Subcounties were vaccinated.

“For a long time, it has been assumed that polio largely affects children under five years of age. However, the confirmation of the virus in a seven-year-old child re-affirms that polio is a threat to all persons irrespective of age in areas where population immunity is compromised,” she said.

Polio has no treatment and the disease can only be prevented through vaccination.

“Every member of the public should report suspected polio cases among children under 15 years who develop sudden onset of weakness (paralysis) of the hands or legs or both without a history of injury to the nearest health facility or chief including nyumba kumi,” Muthoni said.

Last year, globally, there were nearly 800 cases of vaccine-derived polio, according to the Global Polio Eradication Initiative.

Of the 15 polio cases reported in the first quarter of 2023, 14 are from strains of the virus that mutated from the oral polio vaccine used in lower-income nations such as Kenya.

This vaccine is made with a living, weakened virus.

It is preferred because it is cheap and easy to administer. Two doses confer lifetime immunity.

WHO says the vaccine itself does not cause the disease so there is completely no risk when one is immunised with it.

However, children immunised with it can shed the live virus in their stool, which can then spread through sewage in places with poor sanitation.

If the virus stays weak, it can expose an unvaccinated person to polio and give them immunity. But if it mutates and regains virulence, someone who is not vaccinated can become sick with vaccine-derived polio after contact with the contaminated wastewater.

Initial symptoms are fever, fatigue, headache, vomiting, stiffness of the neck and pain in the limbs.

“One in 200 infections leads to irreversible paralysis (usually in the legs). Among those paralysed, five–10 per cent die when their breathing muscles become immobilised,” WHO says.

Experts have also developed a safer, novel oral polio vaccine, which contains a virus that has been weakened so much that it may not even resuscitate under most circumstances.

There is also the inactivated poliovirus (injectable) vaccine used in developed countries which is extremely effective. It requires four injections. But is expensive and requires trained medical staff to carry out such campaigns.