Africa is set to be declared polio-free as Nigeria marks three years without recording a single case of polio infection, thus moving a step closer towards polio-free certification by the World Health Organisation, WHO, in early 2020.
The last time a case of the wild poliovirus was reported in Nigeria was August 21, 2016, in Borno State.
Nigeria is the last country in Africa to record wild poliovirus infections, and if no more cases are found in the next few months, Africa could be declared polio-free.
The last reservoir of polio in Nigeria was Borno State in the northeast, where the Boko Haram insurgency prevented health workers from vaccinating children.
WHO Regional Director for Africa, Dr Matshidiso Moeti, said this three-year landmark achieved by Nigeria sets in motion a comprehensive evaluation process by the Africa Regional Certification Commission to determine if the entire WHO African Region of 47 countries, indeed, could be declared wild polio-free.
He said: "This August's marker on wild polio is a positive sign of progress across the continent, but our work is not yet done.
"We must remain vigilant in our eradication and surveillance efforts: Every country must continue to ensure that it is closely monitoring for any signs of the virus and reaching every child with vaccines.
"We are confident that very soon we will be back here trumpeting the certification that countries have, once and for all, kicked polio out of Africa."
Moeti said if the evaluation process proves the wild virus is gone, Africa will join the Americas, the Western Pacific, Europe and South-East Asia in holding the distinction of being polio-free.
"The path to eradicating polio in Africa has been a monumental effort of multinational coordination on an unprecedented scale, providing vaccinations to hundreds of millions of children and conducting immunisation campaigns in some of the most remote locations in the world, with vigilance and exhaustive surveillance to monitor outbreaks and people on the move," Moeti said.
With Nigeria reaching this important milestone, polio is still endemic in only Pakistan and Afghanistan.
Process of certifying Africa polio-free
To begin the process of certifying Africa polio-free, a team of independent scientists will examine data from Nigeria and 46 countries to look for a sign of overlooked cases or gap in surveillance.
Dr Pascal Mkanda, the Head of Polio for the WHO Africa region, said: "This is a great milestone and achievement. It will give encouragement and a confidence boost to other programmes - if polio, a huge public health problem, can be eradicated it will show that some of the other problems we have in Africa can be dealt with too."
Efforts by FG
To reach this milestone, the Federal Government conducted satellite imaging of isolated communities on hundreds of islands on Lake Chad and set up clinics in markets and at border posts to try and catch all unvaccinated children.
Further, the Nigerian government organised more than a dozen supplementary immunisation campaigns with the oral polio vaccine, strengthened routine immunisation, improved its polio surveillance networks and deployed innovative strategies such as market vaccination, cross-border points and outreach to nomad populations, to reach more children with polio vaccines.
In Nigeria, polio workers painstakingly mapped the many islands of Lake Chad and travelled hours by canoe to reach hundreds of settlements for the first time. They rolled out a new app-based electronic surveillance system called e-Surve to track the virus to its very last hiding places.
Responding to the milestone, Chairman, Polio Committee for Rotary International in Nigeria, Dr Tunji Funsho, remarked: "The challenge was in the northeast, particularly in Borno State, but in the last three years we have been able to access more than 90 per cent of children that we were not able to access in 2016."
"Even in the areas where we cannot easily access the children we have eyes on the ground to detect cases of acute flaccid paralysis and samples can be taken and sent to the appropriate lab.
"These inaccessible children are scattered across a wide geographical area, which would not be able to sustain the circulation of wild poliovirus. However, that does not preclude us from trying to get to these children.
"The challenge now is to make all those who are concerned about polio - the government at every level, partners and donor agencies and countries - to appreciate that the job is just going into another phase. It has not ended.
"The race is not about getting to this milestone. The race to about getting to the child with the vaccine before the virus gets to the child," Funsho stated.
In the meantime, the WHO cautions about lingering challenges to immunisation coverage that are needed to protect communities from the rare non-wild polio strains that can emerge when a population is not thoroughly immunised.
"Reaching every last child with life-saving vaccines as well as strengthening surveillance and routine immunization across the region will be essential to sustain the progress against wild polio and other strains."
The WHO says despite the progress, a number of remaining challenges - including inaccessibility due to conflict and insecurity in some areas, variations in campaign quality, massive mobile populations and, in some instances, parental refusal - have prevented health workers from reaching all children everywhere with polio vaccines in Nigeria.
"Suboptimal routine immunization coverage remains a critical challenge in some countries. As a result, outbreaks of circulating vaccine-derived poliovirus - a rare occurrence in communities with low levels of population immunity - are still possible in several countries across Africa.
Findings show that Nigeria's success in polio eradication is largely attributable to sustained effort, including domestic and international financing, the commitment of health workers, and strategies that reached children who had not previously been immunised because of a lack of security in the northern states.
Poliomyelitis, or polio, is a disease caused by an enterovirus found throughout the world. It is often associated with paralysis of one or more limbs and it's more common for children to experience asymptomatic cases of the disease, which convey life long immunity.
Implementation of the Expanded Programme on Immunisation during the 1980s, led to polio vaccination being included as part of primary health care.
At the 1988 World Health Assembly, it was voted that to eradicate polio worldwide, intensive efforts to vaccinate all children under five for polio should begin.
In 2006, Nigeria had the greatest number of confirmed cases of polio cases worldwide but by the end of 2010, case numbers had declined dramatically through combined government, NGOs, and community effort.
Cases due to wild poliovirus decreased by over 99 per cent since 1988, from an estimated 350,000 cases then, to 33 per cent reported cases in 2018 according to the WHO. As long as a single child remains infected, children in all countries are at risk of contracting polio.