A Russian diplomatic source tells the site that the reason is because the amount of air traffic from Iran to Iraq, Syria and Lebanon has plummeted because of the pandemic - and the weapons transfers to Hezbollah and other terror groups were often done by air.
Moreover, Iran's allies do not want Iran's Quds Force members on their lands for fear of more spreading of the disease.
The number of cases of Covid-19 is being severely underreported in Iran, Syria and apparently Iraq as well, as there are credible reports that Iran is sending many of its forces to hospitals in those countries (as well as Lebanon) for treatment.