North Korea has confirmed 15 more deaths and hundreds of thousands of additional patients with fevers as it mobilises more than a million health and other workers to try to suppress the country’s first Covid-19 outbreak, state media reported on Sunday.

After maintaining a widely disputed claim to be coronavirus-free for more than two years, North Korea announced on Thursday that it had found its first Covid-19 patients since the pandemic began.

It has said a fever has spread across the country “explosively” since late April but has not disclosed exactly how many Covid-19 cases it has found. Some experts say North Korea lacks the diagnostic kits needed to test a large number of suspected Covid-19 patients.

The additional deaths reported on Sunday took the country’s reported fever-related fatalities to 42. The official Korean Central News Agency also reported that another 296,180 people with fevers had been tallied, taking the reported total to 820,620.

The outbreak has triggered concern about a humanitarian crisis in North Korea because most of the country’s 26 million people are believed to be unvaccinated against the coronavirus and its public health care system has been in shambles for decades.

Some experts say North Korea might suffer huge fatalities if it does not immediately receive outside shipments of vaccines, medicines and other medical supplies.

“Without Covid-19 test kits, North Korea is resorting to body temperature checks to guess at infections. But with such a very inferior and inaccurate method of examination, it’s impossible to find asymptomatic virus carriers and control viral surges,” said analyst Cheong Seong-Chang at South Korea’s Sejong Institute.

“As North Korea’s (suspected) Covid-19 infections are explosively increasing, its death toll is expected to continue to rise,” Mr Cheong added.

Since Thursday, North Korea has imposed a nationwide lockdown to fight the virus. That could further strain the country’s fragile economy, which has suffered in recent years due to sharply reduced external trade caused by pandemic-related border shutdowns, punishing UN economic sanctions over its nuclear program and its own mismanagement, observers say.

South Korea and China have offered to send vaccines, medical supplies and other aid shipments to North Korea, but Pyongyang has not publicly responded to the overtures.

North Korea previously rebuffed millions of doses of vaccines offered by the UN-backed COVAX distribution program amid speculation that it worried about possible side effects of vaccines or international monitoring requirements attached to those shots.