- Polio is a serious disease that causes permanent paralysis in survivors.
- Routine immunization in health facilities is the fundamental strategy to protect children against these vaccine-preventable diseases.
- Mass vaccination campaigns are carried out periodically to close the immunity gaps.
Polio and measles are two life-threatening outbreak-prone childhood diseases that can be prevented by vaccination. Rubella is less serious than the two, but it is one of the leading causes of birth defects of the brain, heart, and eyes in babies born to women who come in contact with rubella early in pregnancy.
Polio is a serious disease that causes permanent paralysis in survivors. Measles causes serious, life-threatening illnesses in children under the age of five and is one of the leading causes of blindness.
Polio and measles have the potential for global eradication if population vaccination rates are achieved in excess of 95 percent and are consistently maintained by depriving circulating viruses of a susceptible human host.
Routine immunization in health facilities is the fundamental strategy to protect children against these vaccine-preventable diseases. In most low- and middle-income countries (LMICs), including Kenya, it has been difficult to maintain high immunization coverage due to perennial interruptions in routine immunization services for a variety of causes, such as the actions of health workers. industrial health.
These disruptions in the provision of health services, including immunization, along with sub-national inequalities in coverage caused by highly mobile nomadic and refugee populations, vaccinations of vaccines and the rise of the ongoing Covid-19 pandemic , lead to growing groups of unimmunized and under-immunized children at risk of contracting polio. and measles, which are known to be highly infectious.
Mass vaccination campaigns also known as supplemental immunization activities (EIS) are carried out periodically to close the immunity gaps. HIAs are carried out by vaccinating all children in the target age group, regardless of their vaccination status.
Immunization activities are carried out simultaneously in areas designated as high risk outbreaks as shown by surveillance data. The vaccinations given during these activities are supplemental and the child must still receive scheduled vaccinations during routine immunization clinics.
There is no harm in re-vaccinating a fully vaccinated child, as the additional vaccination acts as a booster. The usual target age group is those under the age of five, who are the age group at highest risk for most vaccine-preventable diseases. A well-run campaign ensures that all unvaccinated, under-immunized, and fully immunized children receive protection at the same time, and this is the best wall of defense against circulating viruses.
Kenya has been free of wild poliovirus (WPV) since 2014. However, the success of wild poliovirus elimination has been limited by the detection of circulating vaccine-derived poliovirus (cVDPV) at polio surveillance sites in the United States. last years.
Mutations in the virus strains contained in oral poliovirus vaccines are responsible for the development of cVDPV. These mutant strains have the potential to spread among poorly immunized populations and can even cause paralysis.
Outbreaks of cVDPV can be stopped by 2-3 rounds of polio HIA with the goal of achieving at least 90% coverage in the target population at risk.
In February 2021, six cases of type 2 cVDPV were detected in Garissa and Mombasa. This required the ongoing polio HIA to be conducted in two rounds spaced four weeks apart. The first round was in May 2021 and occurred in late June.
Measles and rubella are the other vaccine-preventable diseases in which high immunization coverage rates of over 90 percent are needed to ensure adequate protection of the population against outbreaks.
Two doses of the combined measles and rubella (MR) vaccine given at 9 and 18 months are needed to achieve at least 95 percent protection. Only 85 percent of children vaccinated with a dose of the MR vaccine gain immunity against measles.
Over time, a cohort of unvaccinated children accumulates, causing measles outbreaks. Routine immunization services were interrupted in the first months of the Covid-19 pandemic, many parents delaying or skipping MRI vaccination for fear of contracting or exposing their children to Covid-19.
The last MR-SIA was conducted in 2016. It was highly successful and achieved 95 percent coverage of the target population.
A successful campaign ensures that all children achieve protection against measles and meet the long-term goal of guiding Kenya towards elimination of measles and rubella.
Dr. Christine Karanja-Chege, Professor, Department of Pediatrics, University of Kenyatta; Collins Tabu, Director, Immunization Programs, Ministry of Health.