Once named in the same breath as Taiwan and Singapore as an early example of successful virus control, Hong Kong is now in the midst of a worsening outbreak of the coronavirus, with no sign of it slowing down.

Hong Kong residents had been living with reduced pandemic-related restrictions in recent months. But in the past two weeks the region has recorded more than 500 new cases, over 400 of them local.

About 40% have an unknown source and the majority are not imported – a stark inverse in the proportions seen the last time Hong Kong experienced a sudden rise in cases.

On Monday, more than a third of the 73 new cases reported came from an unknown source. It followed a record 108 new cases – 83 local transmissions – reported by the centre for health protection on Saturday.

Brazil 67,964 deaths, 1,713,160 cases

President Jair Bolsonaro dismissed the disease as a “little flu” as it rampaged through his country and mocked measures such as wearing masks. Two health ministers have quit and Brazil’s outbreak is the second-deadliest in the world.

India 21,129 deaths, 767,296 cases

India brought in a strict nationwide lockdown in March that slowed the spread of the virus but did not bring it under control. As the country began easing controls, cases surged and it now has the third highest number. Mortality rates are low, but it is unclear if this reflects reporting problems or a relatively resilient population.

Iran 250,458 cases, 12,305 deaths

Iran had one of the first major outbreaks outside China. A lockdown slowed its spread but after that was eased in April, cases rebounded. Several senior officials have tested positive, and the government has strengthened controls, including making masks obligatory in public places.

Israel 33,947 cases, 346 deaths

Israel had an early travel ban and strict lockdowns, and in April the prime minister, Benjamin Netanyahu, declared the country an example to the world in controlling Covid-19. But cases that in May were down to just 20 a day, skyrocketed after the country started opening up. Partial controls have been brought back with warnings more could follow.

Mexico 275,003 cases, 32,796 deaths

President Andrés Manuel López Obrador joined other populists from across the political spectrum in dismissing the threat from coronavirus; when schools closed in March he shared a video of himself hugging fans and kissing a baby. The outbreak is now one of the worst on the continent.

Philippines 51,754 cases, 1,314 deaths

A strict lockdown from March to June kept the disease under control but shrank the economy for the first time in 20 years. Cases have climbed steadily since the country started coming out of lockdown, and President Rodrigo Duterte has said the country cannot afford to fully reopen because it would be overwhelmed by another spike.

Russia 706,179 cases, 10,825 deaths

Coronavirus was slow to arrive in Russia, and travel bans and a lockdown initially slowed its spread, but controls were lifted twice for political reasons – a military parade and a referendum on allowing Putin to stay in power longer. Despite having the fourth biggest outbreak in the world controls are now being eased nationwide.

Serbia 17,342 cases, 352 deaths

Cases are rising rapidly, hospitals are full and doctors exhausted. But the government has rowed back from plans to bring back lockdown controls, after two days of violent protests. Critics blame the sharp rise in cases on authorities who allowed mass gatherings in May and elections in June. Officials say it is due to a lack of sanitary discipline, especially in nightclubs.

South Africa 224,664 cases, 3,602 deaths

South Africa has by far the largest outbreak on the African continent, despite one of the strictest lockdowns in the world. Sales of alcohol and cigarettes were even banned. But it began reopening in May, apparently fuelling the recent rise in cases which have more than doubled over the last two weeks.

US 132,310 deaths, 3,055,491 cases

The US ban on travellers from overseas came too late, and though most states had lockdowns of some form in spring, they varied in length and strictness. Some places that were among the earliest to lift them are now battling fast-rising outbreaks, and the country has the highest number of confirmed cases and deaths. Opposition to lockdowns and mask-wearing remains widespread.

Source: Johns Hopkins CSSE, 9 July

Photograph: Mark R Cristino/EPA

Of Saturday’s 83 local transmissions, 48 – including taxi drivers and a food market worker – were unsourced. According to data from the Hong Kong University School of Medicine, there was also now a higher proportion of older people, who were more likely to die of the virus, among the confirmed cases.

A 94-year-old man died at Queen Elizabeth hospital at the weekend, becoming the 12th person in the territory to die of Covid-19.

The numbers are small compared with the US, Brazil, and the UK, and especially so considering its proximity to mainland China, the original source of the outbreak.

But while it was praised as an early success story, this new wave has panicked authorities.

“The situation is really severe and there are no signs this is getting under control,” the Hong Kong chief executive, Carrie Lam, said. “This outbreak involves many more clusters of different natures,” Lam said, noting that for the first time aged care homes are affected, and other clusters centred around restaurants, markets, and taxi drivers. It’s far more critical.”

The director of the communicable disease branch of the Centre for Health Protection, Dr Chuang Shuk-kwan, warned the local health system could collapse if there were not improvements soon, and a senior health executive raised the prospect of temporary hospitals.

Lam said Hong Kong’s response had always been “early detection, early isolation, and early treatment”, and so there had been much more testing across the various clusters and high-risk groups recently – about 10,000 per day compared with the usual 7,500.

Dr Leung Chi-chiu, the chair of the Hong Kong medical association’s advisory committee, said the rise in cases showed current measures were too lax. Leung told the South China Morning Post it was unlikely the rise in cases was the result of increased testing, as Lam had suggested.

In the months since the outbreak erupted, a tide of social restrictions has rolled in and out in response to outbreaks.

When the outbreak first began, the government was criticised for not closing border crossings or taking action fast enough. Hong Kong’s economy was already in crisis after a year of city-wide protests and the government did not want to shut down the economy further.

While there was never a full lockdown, many businesses such as gyms, bars and theme parks were forced to close, and the legal size of gatherings was greatly curtailed. As the case numbers dropped, the city opened up again, and there was talk of a travel bubble with Macau and Guangdong province.

Hong Kong’s pandemic border restrictions are among the strictest in the world, with almost no one except Hong Kong residents allowed to arrive by air. But in recent days there has been criticism of the government’s quarantine exemptions, including cross-border freight-delivery drivers, air crew, sea crew and foreign consular staff.

The government said the exemption arrangements were “essential to maintain the necessary operation of society and the economy and to ensure an uninterrupted supply of daily necessities”.

Now the restrictions are back. Masks are mandatory for indoor public places, public servants are working from home, dine-in services in restaurants are banned between 6pm and 5am, bars, karaoke venues and gyms have been ordered to shut again, and a dozen markets in Kowloon have been closed for deep cleaning. Schools are closed until at least August. New quarantine facilities would be opened and anyone entering from seven newly designated high-risk countries must quarantine at government-approved hotels instead of at home.

But questions are being asked if if these moves are all too late. If the numbers did not start to decline in the next two weeks there could be a lockdown, Prof Yuen Kwok-yung, a microbiology expert, told Hong Kong radio on Monday.

“We might possibly need to lockdown. Not a lockdown of the whole city, but … close to a lockdown,” Yuen said.