Teenage Covid-19 patients in southern China bent over test papers and scribbled answers alone in hospital rooms, taking the life-changing "gaokao" college entrance exams despite being in virus-induced isolation.

Guangdong, a populous province bordering Hong Kong, has reported dozens of Covid-19 cases in recent days, prompting authorities to impose travel curbs and mass testing just ahead of the infamous exams, an annual moment of peak anxiety for students and parents.

The gaokao -- which began on Monday and ends Wednesday -- is typically the most stressful point of a Chinese student's life, with results determining admission into universities and shaping career prospects.

The local government has dispatched hundreds of taxis and buses to ferry students from neighbourhoods affected by the outbreak to exam venues, with state broadcaster CCTV showing footage of drivers in hazmat suits spraying down their cars.

Students were split into different rooms based on their level of Covid-19 risk, with contacts of confirmed cases taking the tests in smaller groups.

But infected students with mild symptoms had to take the tough exams solo in brightly lit isolation rooms in the hospital or special locations.

CCTV footage showed one student sitting at a lone desk and scratching his head as he read the exam paper, a bottle of hand sanitizer on the desk and officials monitoring him on a TV screen.

Other state footage showed masked examiners in protective clothing removing completed exam papers from infected students and hanging them up on a clothes-drying rack to be sprayed down with disinfectant.

Provincial officials inspected testing sites in Guangzhou late last week and urged examiners to make sure "students feel comfortable, parents are at ease and society is reassured," the local government said.

Last year's gaokao exams were delayed as schools hesitated to resume mass activities due to the coronavirus, which first emerged in the country in late 2019.

Life in China has since returned almost to normal, with authorities responding to sporadic outbreaks with aggressive testing and localised quarantines.

Guangzhou authorities shut down cinemas and karaoke bars across the city on Tuesday, and have locked down neighbourhoods and ordered travellers leaving the city to show proof of a negative Covid-19 test.

China reported eight locally transmitted Covid-19 cases on Wednesday, all of which were detected in Guangdong province.