A sub-national polio immunization campaign starts today in Sierra Leone to protect an estimated 520,000 children under five years of age using the novel Oral Polio vaccine. The campaign will run for four days and will be implemented by national and district teams and frontline health workers that will go house to house in three districts - Tonkolili, Western Area Urban and Western Area Rural districts - to immunize eligible children.

Between December 2020 and June 2021, the country experienced an outbreak of the circulating Vaccine Derived Poliovirus type two or cVDPV2. A total of 34 confirmed cases in children have been recorded in the country. Similar outbreaks have also been reported in 23 countries in the African region. The outbreak has been attributed to decline in routine vaccination services largely due to the COVID-19 pandemic which also resulted in the decline in population immunity. A coordinated response to the outbreak has led the government and its health sector partners to plan and implement nationwide response interventions including two nation-wide supplementary immunization campaigns in May and July respectively. The campaigns aimed to immunize all eligible children to interrupt transmission of the virus.

However, findings from Lots Quality Assurance Survey and Independent Monitoring of the campaigns by teams that were recruited and deployed by WHO to evaluate implementation of the campaigns showed that Tonkolili, Western Area Urban and Western Area Rural districts consistently failed to meet the threshold of quality implementation of the May and July interventions. The poor performance left a significant proportion of children susceptible to Poliovirus infections.

“Such exposure to the risk of infection is avoidable if herd immunity is achieved by ensuring improved vaccination coverage of the target population”, says Dr Steven V. Shongwe, WHO Representative in Sierra Leone.

To mitigate the risks, the Ministry of Health and Sanitation with technical and financial support from the Global Polio Eradication Initiative (GPEI) comprising WHO, UNICEF, CDC, Bill & Melinda Gates Foundation (BMGF) and other partners is implementing the ongoing mop-up campaign to ensure these districts catch up with the other parts of the country and attain herd immunity against polio in the whole country.

Thousands of frontline health workers, community volunteers and supervisors have been trained and deployed to ensure no child is missed in this campaign. The team will administer the novel Oral Polio Vaccine or nOPV to the eligible children. The same vaccine was used in the two recent campaigns which made Sierra Leone stand out as one of four countries in the world that has rolled out the nOPV. The vaccine has been evaluated to be safe and highly effective in the prevention of poliovirus

Polio is a debilitating and potentially fatal disease. The virus is highly infectious and has no cure once it affects an individual and can lead to paralysis or even death. Young children are the most vulnerable. However, the disease is totally preventable with safe and effective vaccines, which if given multiple times can protect a child for life.

“Vaccination is one of the primary strategies that has contributed to the gains the world has made in the fight against polio. Collective effort by everyone can keep all children safe from the effects of the disease and can make eradication possible in our life time” Dr Shongwe stated.

In August 2020, Africa was certified wild polio free after more than three years of no confirmed case on the continent. However, outbreaks of cVDPV continue to spread in many countries on the continent and other parts of the world. Outbreaks of circulating vaccine derived poliovirus or cVDPV occur in communities with poor environmental sanitation conditions, decline in population immunity due to suboptimal routine immunization and poor quality supplemental immunization activities.

This week at the Seventy-first WHO Regional Committee for Africa, the 47 governments in the region committed themselves to sustain the gains the continent has made against the wild poliovirus and the eradication of all forms Polio viruses that cause the disease.

The Global Polio Eradication Initiative is supported technically and financially by several partners including WHO, UNICEF, Rotary International, the BMGF, CDC, World Bank, African Development Bank, the United Kingdom, the United States of America and national governments.