Trends in acute flaccid paralysis and vaccine-associated paralytic polio among children in Iran: epidemiological profile and performance of the surveillance system (2014-2023).

BACKGROUND

Iran has been recognised as a polio-free country since 2006; however, it remains vulnerable to new cases of polio. Moreover, the risk of transmission is high due to neighbouring endemic countries, illegal refugees, and immigrants.

OBJECTIVES

This study aims to update the epidemiological profile of acute flaccid paralysis (AFP) and vaccine-associated paralytic polio (VAPP) among children <15 in Iran from 2014 to 2023, and to assess the performance of the national AFP surveillance system.

METHODS

This study was conducted as a retrospective descriptive analysis of AFP surveillance data among children <15 from 2014 to 2023. The source of data was the National Notifiable Disease Surveillance System in Iran. Surveillance performance indicators were assessed according to World Health Organisation (WHO) standards.

RESULTS

The AFP cases were 8,368 during the study period. The rate of non-polio AFP increased from 4.19 per 100,000 in 2014 to 5.49 in 2023, and Stool adequacy remained above 80% throughout the study period. Nineteen suspected VAPP cases were identified, all of which were investigated according to WHO criteria and confirmed as non-polio causes. All the performance indicators of the National Notifiable Disease Surveillance System were within acceptable ranges with WHO targets. No cases of wild poliovirus have been reported in Iran since 2000.

CONCLUSION

Iran's AFP surveillance system is robust and sensitive, playing a vital role in maintaining the country's polio-free status. Given Iran's shared border with endemic countries and the risk of introduction of wild or vaccine-derived polioviruses, continuous and enhanced surveillance is essential.