A Harvard academic has defended research suggesting a possible underreporting of coronavirus cases in Indonesia, following fierce criticism from the health minister in the world’s fourth most populous country, which insists it has no cases.

Professor Marc Lipsitch analysed air traffic out of the Chinese city at the centre of the outbreak in China and suggested in a report last week that Indonesia might have missed cases. On Tuesday the Indonesian health minister Terawan Agus Putranto called the report “insulting” and said the country had proper testing equipment.

On Thursday, health officials in Indonesia, which has a population of 272 million and is a popular destination for Chinese tourists, said they were retracing the movements of a Chinese tourist who was diagnosed with coronavirus upon his return from Bali. No-one in Bali has yet been found with symptoms.

The World Health Organization said earlier this month it was particularly concerned about high-risk nations with weaker health systems that may lack the facilities to identify cases.

Lipsitch, from the Center for Communicable Disease Dynamics at the Harvard TH Chan School of Public Health, co-authored a paper that found several locations including Indonesia, Cambodia and Thailand where the number of cases were below the levels expected. “We stand by our research,” he said. “I certainly do not intend it as an insult to any country or person. The role of public health is to spot potential problems and to point them out.”

He said three unlinked cases in neighbouring Singapore – an “expert” country at contact tracing – had increased concern similar transmission was happening under the radar elsewhere.

Quick guide What are coronavirus symptoms and should I go to a doctor? Show Hide What is Covid-19? Covid-19 is caused by a member of the coronavirus family that has never been encountered before. Like other coronaviruses, it has come from animals. The World Health Organization (WHO) has declared it a pandemic. What are the symptoms this coronavirus causes? According to the WHO, the most common symptoms of Covid-19 are fever, tiredness and a dry cough. Some patients may also have a runny nose, sore throat, nasal congestion and aches and pains or diarrhoea. Some people report losing their sense of taste and/or smell. About 80% of people who get Covid-19 experience a mild case – about as serious as a regular cold – and recover without needing any special treatment. About one in six people, the WHO says, become seriously ill. The elderly and people with underlying medical problems like high blood pressure, heart problems or diabetes, or chronic respiratory conditions, are at a greater risk of serious illness from Covid-19. In the UK, the National health Service (NHS) has identified the specific symptoms to look for as experiencing either: a high temperature - you feel hot to touch on your chest or back

a new continuous cough - this means you’ve started coughing repeatedly As this is viral pneumonia, antibiotics are of no use. The antiviral drugs we have against flu will not work, and there is currently no vaccine. Recovery depends on the strength of the immune system. Should I go to the doctor if I have a cough? Medical advice varies around the world - with many countries imposing travel bans and lockdowns to try and prevent the spread of the virus. In many place people are being told to stay at home rather than visit a doctor of hospital in person. Check with your local authorities. In the UK, NHS advice is that anyone with symptoms should stay at home for at least 7 days. If you live with other people, they should stay at home for at least 14 days, to avoid spreading the infection outside the home.

A leading hypothesis for the lack of reported cases in Indonesia is that imported cases were missed, said Lipsitch, who pointed to a Sydney Morning Herald report that the country had no test kits until 5 February in support of the theory.

“If cases have been introduced into Indonesia, then there is a good chance that more cases are circulating via transmission from those cases. If so, they may go undetected for some weeks as the individuals may not seek care or may not be suspected and tested for coronavirus, especially if there is no direct link to China.”

Putranto told reporters in Jakarta earlier this week: “They can be baffled but it’s a fact [that there are no cases]”. The former military doctor was reprimanded in January by the Indonesian Medical Association Ethics Council for pushing his own controversial “brainwash” treatment for stroke victims.

One senior former diplomat in the country, who did not want to to be named, said he did not believe official assertions that no cases had been found. “There’s a tendency to hide or gloss over serious problems in the top levels of the government,” he said. “I’m a bit concerned.”.

Dr Yanri Wijayanti Subronto, a lecturer at Gadjah Mada University in Yogyakarta, said the local health offices had surveillance teams in place and that “this is a system that works”.

But other experts expressed concern over inadequate training of public health practitioners and over public messaging.

Dr Riris Andono Ahmad, director of the Center for Tropical Medicine at Gadjah Mada University in Yogyakarta, said facilities had been set up to handle potential cases but health practitioners have not received sufficient training. “We need to be much more alert,” Ahmad said.

Currently, the policy in Yogyakarta is to ship all samples from potentially affected patients to testing facilities in Jakarta, he said.

“Public awareness of effective prevention measures is not high,” he said. “For instance, there was a lot of panic-buying of masks, but masks only work with people who are already sick. Whereas something that actually works, like washing hands more frequently – I don’t know how many people are really doing it yet.”

Officials in North Korea, another country with close ties to China that has not reported a case, are clearly extremely worried about the danger of an outbreak. Authorities in the country, which has only a rudimentary health system, have effectively put the entire country into quarantine, sealing the borders and stopping all international trains and flights.

Despite these precautions, there have been reports of cases in the north, and in the capital Pyongyang, said Jiro Ishimaru, the head of Osaka-based Asia Press, who runs a secret network of citizen journalists inside North Korea.

“There are lots of rumours flying around that some people have been infected near Dandong, just on the Chinese side of the border, and the Rason special economic zone [on the North Korean side],” Ishimaru told the Guardian. “I have heard from our contacts that some people in Rason have been put in isolation for 20-30 days to prevent an outbreak.”

The border closure has already had a dramatic impact on the economy. “Given the North’s huge dependence on China for things like food, cooking oil and gasoline, there are shortages of daily necessities. People are asking why that is happening, and that’s how they heard about the coronavirus,” Ishimaru said. “The authorities can deny that the coronavirus has reached North Korea, but inflation and shortages are a fact of life.”

Additional reporting by Krithika Varagur in Jakarta and Justin McCurry in Tokyo