Tehran University of Medical Sciences Iranian Journal of Microbiology 2008-3289 13 4 2021 08 11 502 508 Mahsa Javadi Department of Virology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran; Department of Virology, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran Ahmad Nejati Department of Virology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran Maryam Yousefi Department of Virology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran Mahmood Mahmoodi Department of Epidemiology and Biostatistics, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran Zabihollah Shoja Department of Virology, Pasteur Institute of Iran, Tehran, Iran Shohreh Shahmahmoodi Department of Virology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran 2020 11 16 2021 07 09 Background and Objectives: Human Enterovirus 71 (EV-A71) is the causative agent for many dermal to neurological diseases especially polio-like paralysis outbreaks around the world. This study, the first of this kind in Iran, aimed to find neutralizing antibodies against EV-A71 in serum of healthy individuals in different age groups based on neutralization test (NT). Materials and Methods: In this cross-sectional study, 547 serum samples were collected from healthy individuals who were referring for routine checkup tests (aged from under 6 months to over 31 years old) to Imam-Khomeini Hospital in Tehran during January-December 2015. Serum samples were examined by NT in cell culture to detect neutralizing antibodies against EV-A71. In the next step, some of the positive samples were subjected to complete titration to determine the exact titer of anti-EV-A71 antibodies. Results: Of 547 samples, 310 (56.7%) were positive for EV-A71 neutralizing antibody. The presence of the antibody increased with age (p<0.001), and there was a significant statistical relationship between sex and the presence of antibody (p=0.009). Conclusion: Our results demonstrated an apparent but limited circulation of EV-A71 in our society. After the worldwide eradication of poliovirus, EV-A71 which can cause polio-likes syndrome, might be the new challenge for our health care system as regard more in depth research is however needed. https://ijm.tums.ac.ir/index.php/ijm/article/view/2852 https://ijm.tums.ac.ir/index.php/ijm/article/download/2852/1372