The department's head, Song Tao, said in a letter to the Secretary of Iran's Expediency Council, Mohsen Rezaei, that China was ready to launch scientific cooperation and share its experience with Iran in the battle against the virus.

On April 16, Zarif, the Iranian foreign minister, published a "thank-you note" in Chinese on his Twitter account.

The note stated, "I thank China for providing Iran with anti-epidemic materials, sending medical experts, and condemning the continued illegal sanctions by the United States that have seriously hindered Iran's efforts to fight the epidemic."

Threat not over

Although Iran remains one of the countries in the Middle East hardest hit by the virus, the number of new daily cases has fallen, triggering hopes that the country may be turning the tide.

On April 22, Iranian Health Minister Saeed Namaki said that in the previous 18 days, "thanks to divine blessing as well as the efforts of our colleagues ... we were able to reduce the number of new patients by 53 percent and the death toll by 30 percent daily".

Iranian government spokesman Ali Rabiee also said the infection rate and the number of deaths from COVID-19 are falling in Iran.

However, Iraj Harirchi, deputy minister of health, said a decline in the number of cases in the hardest-hit provinces, such as Qom and Gilan, does not mean that the threat is over, but that precautionary measures must continue to avert a new peak.

"Until further notice, a second, third and umpteenth peak is quite probable throughout the world, even in countries that are apparently clear (of the virus)," he said.

Harirchi added that people must get used to living with the virus and should observe health advice and social distancing regulations until a vaccine is produced.

He said the health ministry had launched the second stage of nationwide screening programs, with more than 99 percent of the population covered in the first stage.

Rabiee said, "We must live with social distancing and follow instructions until the day the health ministry announces that the virus has been defeated."