Amidst severe polio outbreaks in Asia, Africa and the Middle East, the WHO says that a “coordinated international response” is needed. Studies show that an extra dose of the of Inactivated Polio Vaccine (IPV) may be the solution.
As the WHO has declared the spread of polio an “international public health emergency,” growing pressure has been placed on co-coordinating an international response to resolve the crisis. It is the second time in history that the WHO has ever made such a declaration, the first being during the swine flu pandemic of 2009.
The polio virus is endemic in just three countries – Pakistan, Afghanistan, and Nigeria. However, attacks on vaccination campaigns, particularly in Pakistan for religious reasons, have allowed the virus to spread across borders. Syria, which was polio-free for 14 years, was re-infected with the virus from Pakistan.
A study by the Lancet has suggested that giving children under the age of 5 an additional dose of the inactivated polio vaccine boosts their immunity to the poliovirus and should be added to vaccination programmes in polio endemic countries and those countries where the virus is likely to spread across borders.
Dr.Jacob John, the lead author of the study, has said “Adding a supplementary IPV dose to children already vaccinated with oral poliovirus vaccine (OPV) may hasten polio eradication by boosting herd immunity in endemic regions, act as a booster to prevent international spread by travellers, and minimise the risk of polio outbreaks due to imported wildtype or vaccine-derived polioviruses.
Although OPV is highly effective, easy to administer and relatively inexpensive, its ability to generate a strong intestinal immunity to infection wanes as early as a year after vaccination. Thus, vaccinated children and adults can still be infected and shed wild poliovirus, contributing to the spread of the disease. In attempt to increase protection to the virus in children whose immunity might have waned, scientists who carried out this study examined the effect of an additional dose of IPV on both systemic and intestinal immunity in children from Vellore, India (aged 1 to 4 years) who had received at least five doses of OPV as part of routine immunisation at least 6 months previously. Children were randomly assigned to receive a dose of IPV (225 children) or no vaccine (225) at enrolment.
The results showed that the additional IPV dose substantially boosted levels of protective antibodies in the blood and intestinal immunity against poliovirus compared with no vaccine.
According to Professor Grassly, senior author of the study from Imperial College London, UK, “The substantial benefit of using IPV rather than further doses of OPV to boost intestinal immunity in children within the typical age range for mass vaccination supports its use as part of the global eradication programme.”
Read more about it here: The Lancet: Extra dose of inactivated polio vaccine boosts immunity in children