States in the Northwest keep pressure on vaccine-derived polio


On 25 August 2021, African countries marked one-year anniversary of Polio certification. Programme managers, health workers and polio survivors in Nigeria also celebrated the wild polio- free status in the country.  

The victory notwithstanding, the fight against other forms of the poliovirus is not over. Cases of vaccine-derived polio caused by low and infrequent immunization are still being recorded in Nigeria, with the northwest accounting for more than 55% of the total cases in the country highlighting the need for continued vigilance to nip a possible outbreak in the bud.

The Kano State Commissioner for Health, Dr Aminu Ibrahim Tsanyawa says, “The circulating vaccine derived polio Virus type -2 outbreak indicates the importance of continuing to receive Routine Immunization (RI) that is available in our health facilities, in order to reduce the risk of polio. That is why, expeditious action must be taken to strengthen our children’s immunity, to prevent further spread of the disease in our state and the country as a whole”.

Following the report in  late 2020 of cases of vaccine-derived polio virus (cVDPV) disease in the northwestern states (Jigawa, Kano, Kaduna, Katsina, Kebbi, Sokoto and Zamfara), health authorities there are unrelenting in their actions to vaccinate all children under five years (10,637,566); the age at which the vaccine-derived polio disease is likely to set in.

“We continue to do this work because it is important for the children’s future,” says 26-year-old Amina Ibrahim, a vaccinator in Sokoto who works in communities despite the COVID-19 pandemic. “What we do is make sure we wash our hands, wear our face masks and maintain two-meters physical distance as we go from house to house.” 

Addressing menace of cVDPV

First discovered in Madagascar in 2001, circulating vaccine-derived polio often occurs when a child who has been vaccinated with the oral polio vaccine (OPV) and who is in a poor sewage area passes stool or urine. The weakened live virus present in the urine or stool could find its way into the systems of other under-immunised kids through contaminated water or food and mutate, becoming infectious and causing life-long paralysis and in some cases, death. 

Circulating vaccine-derived polio is rare but it poses risks to children everywhere because of its highly infectious nature. Nigeria has been experiencing outbreaks since 2018. The disease is fought in the same way wild polio is: with vaccines that provide the most important protection for children.

To halt the emergence of more cases of the disease, Northwest zone authorities are pushing massive statewide vaccination campaign. With a population of 53,187,831 (2021 projected), the zone is targeting about almost 11 million children during outbreak response vaccination exercises.

While the oral polio vaccine was used to protect against wild poliovirus in Nigeria, vaccine-derived polio disease is warded off with the novel oral polio vaccine (nOPV2). The World Health Organization (WHO) recommends regular immunization, at least twice for children, to reduce risks of infection. House to house team members administer two drops of the vaccine to produce a stronger immune response, according to the WHO. 

Maintaining vigilance

Health authorities in all the seven states are also intensifying surveillance with the help of community informants to identify and isolate possible cases of vaccine-derived polio disease in the various local government areas. 

Supported substantially by WHO, health officers regularly monitor the environment as well, examining stool and sewer samples in at-risk communities to monitor virus activity, a method that proved useful in finding and isolating wild poliovirus cases in the past years. 

The surveillance and vaccination efforts are crucial for the northwest of mostly farmers and cattle herders. In the zone, the state’s geography makes it an easy target for infections. In the  NWZ, four states share borders with Niger Republic which recorded cVDPV in 2020. The borders in the West African region are widely known to be porous and polioviruses are themselves highly infectious. In 2008, cases of wild polio spread from Nigeria to countries as far as Yemen.

Parents and caregivers mobilized for vaccination

The thoughts of life-time paralysis have made Sokoto parents especially eager to see their kids protected with vaccines. While years back parents saw many cases of children affected by polio growing up, the difference is clear now, with fewer children having to go through the pain of paralysis. Nigeria’s polio successes, hyped by traditional institutions, also boosted confidence in vaccines, a significant feat in a population that is often wary of medical services seen as foreign. 

“In the North West Zone, traditional institutions have a renewed commitment to support WHO in tackling the upsurge of cVDP2 through improved community sensitization to achieve optimal routine immunization coverage across the zone”, says Dr Jalal Saleh, WHO Zonal Coordinator.
Ladidi Mohammed, a 16-year-old mother in Kazaure LGA Jigawa state says, “I allowed my child to be vaccinated because I believe my child will be protected from diseases of Polio, measles, Meningitis and other childhood diseases. Our traditional leader always sensitizes us on the importance of vaccination and I thank government for ensuring that our children are vaccinated and prevented from getting infected.”
But despite the vaccination push, health workers say they face hurdles in reaching some populations, leading to low vaccination coverage, especially with the impact of Covid 19 disease lockdown.  

Residual challenges
Parts of the NWZ are insecure due to activities of bandits, armed groups, for one and another, rumours around vaccines, with one rumour saying they cause infertility in children. It is also challenging to reach nomadic cattle herding groups who make up a significant population in Nigeria’s north. 

Crucially, because of inadequate education, many do not believe in the need to be vaccinated after polio has been declared eradicated and are shunning ongoing vaccinations against both wild and vaccine-derived polio. 
These factors have resulted in Nigeria recording 201 outbreaks of vaccine-derived polio between 2018 and 2021 alone. Authorities declared a state of emergency on routine immunization in 2017, created state and local emergency routine immunization coordination centers and directed more state resources towards delivering vaccines. 
“There has been a resurgence of vaccine-derived poliovirus over the years because there’s a significant proportion of under-immunized children,” says Dr Walter Kazadi Mulombo, WHO Nigeria Country Representative. “WHO will continue to support the country with experienced personnel in conducting effective immunization drives particularly in the outbreak areas”. 

Despite the challenges, health workers continue to deliver vaccines and hop door to door and are helping parents understand the benefits of vaccines. Nomad trails are tracked with geo-information mapping systems so that vaccinators always know where families are. In communities with poor health infrastructure, state authorities and WHO are supplying drugs for minor ailments to build trust. And there is a productive collaboration with security agencies and local security groups that is helping health workers deliver vaccines safely to conflict-affected communities.