Analysis of Traveler Data Suggests Iran's COVID-19 Trajectory Far Higher Than Officially Reported

As outbreaks of coronavirus disease 2019 (COVID-19) have spread across the globe, countries including China, Italy, Spain, and the United States have emerged as closely watched hotspots.

However, another country, Iran, has received significantly less attention despite that fact that it’s believed to be one of the hardest-hit countries. Officially, the country didn’t have any cases of COVID-19 until mid-February, when it reported its first 43 cases. As of March 26, the country had reported more than 29,000 cases.

However, a new report based on an analysis of exported cases and air travel patterns suggests the country’s early reports grossly underestimated the scope of the problem in the country. If true, the findings would likely mean the current number of cases is also far higher than what is being reported.

Investigators from the University of Toronto wanted to gain a better understanding of the COVID-19 problem in Iran, and also to quantify the impacts of an Iranian outbreak on the country’s neighbors.

The team decided to analyze air transport numbers, including direct and total travel from Iran to other countries. They zeroed in on reported cases in which patients in other countries (Canada, the United Arab Emirates, and Lebanon) had had their infections traced back to Iran. Those data were compiled with other metrics, such as travel rates to those countries and others, and the strength of a particular country’s capacity to detect and respond to an outbreak. From there, the team attempted to estimate the number of cases that would likely need to be present in Iran in order to result in the 3 internationally exported cases.

Their conclusion: Iran likely had around 18,300 cases at the time of the study’s publication in mid-March. Those figures suggest a much higher trajectory than had been officially reported by Iranian public health officials. The results were published in the Annals of Internal Medicine.

The findings also have implications for countries with close ties to Iran. The study reports that 212,000 people flew out of Iranian airports in February 2019. Nearly half of those travelers flew to one of 3 cities: Istanbul, Turkey; Najaf, Iraq; and Dubai, United Arab Emirates. Among the top 10 cities, 4 are located in countries that have a score of less than 0.6 on the Infectious Disease Vulnerability Index (IDVI), which rates countries on a scale of 0 to 1.0

Corresponding author Ashleigh R. Tuite, MD, PhD, of the University of Toronto, wrote that the low IDVI scores suggest elevated vulnerability to infectious disease outbreaks in those countries, as well as a limited ability to detect cases. She and colleagues said it’s highly likely countries like Iraq and Syria have cases from Iran, but had not yet identified them at the time of the study.

“Given the low rankings for Lebanon and Canada for outbound air travel, it is unlikely that cases would be identified in these countries and not in Iraq, Syria, or Azerbaijan (countries with higher travel volumes but low IDVI scores),” Tuite and colleagues write.

Indeed, since the publication of the article, Iraq, Azerbaijan, and Syria have reported cases of COVID-19, though the numbers are small; in Syria, just 5 cases have been officially reported.

Tuite and colleagues say the data make a strong case for significant resources to be sent to these countries.

“Supporting capacity for public health initiatives in the region is urgently needed,” they conclude.