Shanghai authorities put up barriers on Monday around a city centre area where hundreds of people protested over the weekend against heavy COVID-19 measures, one of several demonstrations that have flared across the country.

From the streets of Shanghai and Beijing to university campuses, protesters made a show of civil disobedience unprecedented since leader Xi Jinping assumed power a decade ago to oversee the quashing of dissent and establishment of an extensive high-tech social surveillance system.

"We hope to end the lockdown," said 28-year-old Shi at a candlelight vigil in Beijing late on Sunday. "We want to live a normal life. We should all bravely express our feelings."

There was no sign of new protests on Monday in Beijing or Shanghai. The Public Security Bureau did not immediately respond to a request for comments.

The backlash against COVID restrictions is a setback for China's efforts to eradicate the virus, which is infecting record numbers of people and raising concern about the economic toll of lockdowns on the world's second-largest economy.

The protests roiled global markets on Monday, sending oil prices lower and the dollar higher, with Chinese stocks and the yuan falling sharply.

Three years after the virus emerged in the central city of Wuhan, China remains the only major country not treating COVID as endemic, imposing arduous restrictions on the daily lives of hundreds of millions across the country.

China's zero-COVID policy has kept its death toll low compared with many other countries and officials say it must be maintained to save lives, especially among the elderly given their low vaccination rates.

China has not approved any Western-made COVID shots and a Hong Kong study late last year found that its CoronaVac shot made by Sinovac did not produce adequate levels of antibodies to fight the Omicron variant.

Experts say China must ramp up its vaccinations before it can contemplate reopening and many analysts say that is unlikely before March or April.