WEDNESDAY, March 18, 2020 (HealthDay News) -- Based on countries with identified cases of coronavirus 2019 (COVID-19) originating in Iran, the COVID-19 epidemic in Iran is likely to be of a substantial size, according to a research letter published online March 16 in the Annals of Internal Medicine.
Ashleigh R. Tuite, Ph.D., M.P.H., from the University of Toronto, and colleagues quantified the COVID-19 outbreak size in Iran based on known exported case counts and air travel links between Iran and other countries.
The researchers found that in February 2019, 212,000 persons traveled from Iranian airports to international destinations. Four of the top 10 traveler-receiving cities are in countries in an Infectious Disease Vulnerability Index score lower than 0.6, indicating elevated vulnerability to infectious disease outbreaks and limited ability to detect cases. In February 2019, United Arab Emirates, Lebanon, and Canada ranked third, 21st, and 31st, respectively, for outbound air travel volume from Iran. Assuming an outbreak duration of 1.5 months in the country, an estimated 18,300 COVID-19 cases would have had to occur in Iran in order to observe these three internationally exported cases reported at the time of writing.
"The lack of identified COVID-19 cases in countries with far closer travel ties to Iran suggests that cases in these countries are probably being missed rather than being truly absent," the authors write. "This is concerning, both for public health in Iran itself and because of the high likelihood for outward dissemination of the disease to neighboring countries."