Iran study suggests much higher coronavirus infections, recovery rate than official numbers

A new study out of Iran suggests that up to one-third of its population may have contracted coronavirus, another in a growing line of scientific surveys that suggest COVID-19 has been far more widespread, and far less deadly, than official numbers would indicate. 

The study, conducted by researchers out of the University of Tehran and the University of Guilan, sought to "determine seropositivity of COVID-19 virus infection in population of a highly affected area [Guilan] in north of Iran."

The researchers employed a "population-based cluster random sampling design through phone call invitation" to recruit test subjects, which eventually numbered over 550. Respondents to the study, which has not yet been peer-reviewed, were tested for antibodies that the human immune system develops to fight coronavirus. 

The estimated antibody rate for the respondents ranged from 21 percent to 33 percent.

"Based on these estimates the range of infected people in this province would be between 518,000 and 777,000," the researchers wrote.

If true, that number would represent a massive increase in the number of cases in Iran, which claims to have recorded a little over 96,000. It would also suggest that the disease is significantly less fatal that current estimates. 

"The population seropositivity prevalence of COVID-19 virus infection indicated that the asymptomatic infection is much higher than the number of confirmed cases of COVID-19," the researchers concluded. 

Studies in U.S., Europe show similar, though smaller, findings

Scientists around the world have undertaken similar studies in recent weeks, as health officials and governments scramble to determine just how far the novel coronavirus has spread throughout the world. 

In California last month, researchers estimated based on the results of a serology test that as many as 81,000 residents of Santa Clara County might have contracted COVID-19, compared to the roughly 1,800 confirmed cases. In Chelsea, Massachusetts, meanwhile, tentative data suggested as much as 30 percent of the population there may have already recovered from the disease. 

In New York this past week, Gov. Andrew Cuomo said early results indicate as many as 25 percent of all New York City residents may have had the illness. Hospital screenings in New York earlier this year revealed that 15 percent of pregnant women may have contracted the disease. 

 In Japan, researchers claimed to have found "396 to 858 fold more than confirmed cases," though that number is likely influenced significantly by Japan's notably low nationwide testing rate. 

A study at a French high school last month revealed a 25 percent antibody rate. And in Florida's Miami-Dade County last month, scientists announced that true infection rates there could be 20 times higher than reported rates.