Choi can also remember dealing with a nationwide measles outbreak in 2006, armed only with a thermometer; and a 2009 flu pandemic in which even "more people died than during SARS" -- a situation made worse by an acute shortage of medicine.

In previous epidemics, Choi explains, there was never an incentive for local officials to travel house to house to accurately count cases -- they had no masks or gloves and they figured statistics would be massaged by the regime to suit its needs.

He assumes little has changed since he left and that history, if not exactly repeating itself, is at least rhyming.

What's North Korea hiding?

As with past outbreaks of disease in North Korea, one of the biggest concerns surrounding the country's Covid outbreak is that Pyongyang's penchant for secrecy makes it hard to accurately gauge its severity.

International NGOs and most foreign embassies have long vacated the country and tightly sealed borders mean access is impossible, making the accounts of defectors like Choi all the more important.

The incredibly low official death toll the country has reported inevitably raises suspicions that Pyongyang is trying to hide a bigger problem.

"I have some questions," South Korea's Unification Minister Kwon Young-se said pointedly last week, noting the story being peddled by the North's state-run media contrasted sharply to the experience of the rest of the world.

New Covid variants, cholera?

The biggest fear initially was that an outbreak in an unvaccinated, malnourished population with primitive health care would be catastrophic.

Tomas Ojea Quintana, UN Special Rapporteur for human rights in North Korea, said knowing the scale of the outbreak is impossible at the moment -- though he had heard unconfirmed reports of deaths among the elderly and malnourished children.

"At least in my position, I am not able to contrast this fear that we had at the beginning of 2020 about the catastrophic consequences of Covid in (North Korea) and its current situation."

There are also fears that new, possibly more virulent, variants could emerge from unchecked transmission through North Korea's population of about 25 million.

Dr. Kee B. Park, an American neurosurgeon who until the pandemic started had been visiting North Korea twice a year to work alongside North Korean counterparts, training them and performing surgeries, said the country seemed unwilling to share information and this was "not good for them (and) it's not good for the rest of the world."

"We have to share information on any kind of new changes in the characteristics of the virus, for instance, mutations, right," he said.

"We need to be aware of the fact that high replication can lead to new variants. The only way to detect that is to share information with each other."

In June, North Korea said it was experiencing an outbreak of an unidentified intestinal disease in South Hwanghae Province, about 75 miles (120 kilometers) south of the capital Pyongyang.

At the very least, the announcement demonstrated the country's vulnerability to disease outbreaks and its lack of medicines.

Park believes North Korea is probably dealing with an outbreak of typhoid fever or cholera.

"Somewhere like North Korea, you can expect high rates of infectious diseases. In fact, for children under 5 years of age, diarrheal diseases are the number one killer."

A ray of hope?

One ray of hope for Park was the country's ability to vaccinate its population quickly -- demonstrated during its nationwide inoculation program for the 2006 measles outbreak.

"The first cycle, they were averaging a million jabs a day, then at the second cycle, later on in 2007, they were averaging over 3 million injections a day," Park said.

"If all conditions are right, based on those numbers, they can vaccinate the entire population at least for the first jab in eight days."

But any optimism is tempered by the reticence of a country sometimes referred to as "the hermit nation" to accept outside help.

"They're socialized for scarcity," Park said. "They struggled to supply hospitals with some of the things we take for granted," he recalled of his time working in the country, saying surgeons would reuse equipment such as scalpels until they were blunt and unusable.

Offers of aid from the United Nations, United States, South Korea and others have all been ignored.

Some aid, however, has made its way into the country from China. Customs data shows from January to April, North Korea imported more than 10 million masks, 1,000 ventilators and more than 2,000 kilograms of unspecified vaccines.

Global vaccine alliance Gavi said last month it understood North Korea had accepted Covid vaccines from China and had started administering doses.

A Gavi spokesperson told CNN that North Korea had "still not submitted a formal request to COVAX for vaccine support but we remain ready to help should they do so."

The isolation of Covid sufferers in the country was highlighted by the recent attempts of a defectors' activist group to send medicine across the demilitarized zone -- the de facto border between North and South Korea.

The Fighters to Free North Korea said it had sent large balloons carrying medical supplies such as Tylenol and Vitamin C across the border in June as well as some carrying anti-regime leaflets in late April.

These balloon flights are against South Korean law and have been discouraged. Unification Minister Kwon told reporters he understands "such organizations' sentiments, but I think they should refrain."

Starvation and a second 'Arduous March'

Meanwhile, disease -- whether it's Covid or anything else -- may not be the biggest problem facing North Koreans.

One defector, 44, who is living in South Korea, said she had been contacted by her family in the North soon after the outbreak was reported. Conversely, when it came to Covid, they were most concerned about her -- a reflection of Pyongyang's considerable propaganda prowess.

"They said [North Korean television had] reported that many people in South Korea were dying from Covid so they were worried about me," she said. "They weren't very concerned about the virus."

What her family were extremely worried about, however, was the lack of food.

"They told me that the food situation was worse than during the Arduous March in the 1990s ... I'm very worried knowing how difficult things were (back then)."

The Arduous March refers to a period of devastating famine when North Korea's economy took a hammer blow from the collapse of the Soviet Union, which ended the flow of aid into the country.

Hundreds of thousands of people, or as many as 10% of the country's population, are estimated to have starved to death. Some estimates put the death toll even higher.

The defector did not ask her family whether anyone is dying from starvation as she never talks about anything political during these rare contacts with her family. The possibility that authorities might be listening in is too great. She asked CNN not to be identified in case her family faced retribution.

But Quintana, the UN Special Rapporteur, said the danger was very real and that he was urging the Kim regime and others involved in North Korea "to basically understand there is a serious risk about starvation in North Korea."

Whether Kim is likely to listen is another matter.

State-run television has been running coverage of the North Korean leader touring pharmacies, ordering his military to stabilize medical provisions, and even donating some of his private medical supplies last month to the fight against the as-yet unidentified intestinal outbreak.

To Choi, the doctor who fled North Korea in 2011, such images are to be expected when truth is treated like a rubber band. It's a show and nothing more, he said.

"The North Korean authorities are not struggling, North Korean citizens are the ones having a hard time ... if you survive it's great, but there's nothing we can do if you die".