Iran's Health Ministry has told people at risk of severe Covid-19 to wear masks in crowded indoor spaces after a rise in cases driven by an Omicron sub-variant on September 30.

The share of samples testing positive for Covid-19 has passed the ministry's high alert threshold and reached 17.4%, according to surveillance data published on September 28.

A week earlier the paper reported that positivity had risen for five weeks running to 17%, double the 8.9% recorded in the same week a year earlier.

The advice comes as a US naval blockade of Iranian ports squeezes household budgets. Inflation was close to 85% in the month to August 22, according to central bank data, and families have been cutting back on medicine along with meat and dairy.

Supply itself has held up better with customs data showing medicine imports nearly tripled to $960mn between March 21 and August 11 with Washington saying the blockade does not target medicines or essential goods.

Ghobad Moradi, head of the ministry's communicable diseases management centre, said the common symptoms are sore throat, cough, fever, fatigue and muscle pain, with digestive symptoms in some patients.

Most cases are mild to moderate, he said, but the illness can be more severe in older people and in those with underlying conditions or weak immune systems.

The ministry named people over 80, people over 60 with underlying conditions, the immunocompromised, the severely obese and pregnant women as the groups most at risk of severe disease.

Moradi also called for better ventilation at home and at work, regular hand washing and an end to greeting with handshakes and kisses, and recommended influenza vaccination for older and at-risk people where vaccine is available.

The latest surveillance round found that 8.1% of outpatients had flu-like symptoms and 10.5% of hospital inpatients had severe acute respiratory illness.

The circulating strain belongs to the XFG Omicron sublineage, while influenza B is spreading mainly among children.

Iran was among the countries hit hardest in the early years of the pandemic. In October 2020, during a third wave, hospitals were ordered to stop admitting non-emergency patients.

Moradi gave similar mask advice during an earlier rise in cases in May 2025, local media reported at the time.