Shanghai has reported 12 new Covid-19 related deaths, up from 11 the previous day, as frustrations among residents of China's most populous city continue to boil over amid a harsh lockdown.

The city of 25 million people, battling China's biggest coronavirus outbreak so far, recorded 20,634 new local asymptomatic infections yesterday, up from 15,698 a day earlier. Total new symptomatic cases reached 2,736, up from 1,931 on April 21, official data showed.

The patients who died had an average age of 88, all had underlying health conditions and none had been vaccinated, the Shanghai government said.

China has yet to introduce its own mRNA vaccines, and has chosen not to import those developed overseas.

Though frustrations continued to bubble over in Shanghai's sealed off residential compounds, local officials maintain there will be no relaxation until new cases outside of quarantine areas have all been cleared.

"The more critical the period becomes, the more we need to grit our teeth and focus our strength," Shanghai Mayor Gong Zheng was quoted as saying on Shanghai's official government WeChat channel.

The number of cases outside quarantine areas stood at 218 yesterday, down from 250 the previous day.

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In a study published by China's Disease Prevention and Control Centre, medical experts in the northeastern city of Jilin, the location of another recent outbreak, said China's vaccines have been effective so far, though new emerging Covid-19 variants remained unpredictable.

They said "the data is strong enough to indicate the public significance of the strategy of full and booster vaccination, particularly for the elder population."

Liang Wannian, head of a Covid-19 expert advisory body with the National Health Commission, told state television that China's current "dynamic" zero-Covid policies had given the country "time to prepare", allowing it to strengthen vaccination levels.

Shanghai's full-city lockdown began at the start of April, though many residents have been confined to their homes for much longer, which has added to exhausted frustrations.

A city official acknowledged that the disruptions were putting Shanghai's environmental health under pressure, with less than half of its sanitation workers currently active, affecting garbage collection rates.

Even after shutting down for more than 30 days, some compounds are still reporting new cases, casting doubt on the efficacy of China's approach.

On social media, netizens battled against censors overnight to share a six-minute video entitled 'The Voice of April' a montage of voices recorded over the course of the Shanghai outbreak.

Panning across Shanghai's silent skyscrapers, the video consists of residents complaining about the lack of food and medicine, as well as the heavy-handed tactics of city authorities.

All direct references to the film were removed from the Weibo microblogging service by morning, though some comments criticising the censorship survived.

Covid-19 was the third leading cause of death in the US in 2021

A new government study in the United States said that Covid-19 was the third leading cause of death in 2021 with death rates rising for most age groups.

Covid-19 was the underlying or contributing cause of 460,513 deaths (111.4 per 100,000 deaths) in the United States in 2021, compared to 93.2 per 100,000 deaths in 2020, a near 20% jump, the study by the U.S. Centers for Disease Control and Prevention showed.

Researchers found that Covid-19 deaths were highest among those aged 85 and over, and lowest in children.

The researchers analysed death certificate data and found that 2021 saw the highest overall death rate since 2003, with heart disease and cancer being the first and the second leading cause of death respectively.

Meanwhile South Africa is seeing a spike in coronavirus cases after a relative lull in new infections data from the National Institute for Communicable Diseases has shown.

A total of 4,631 infections and one Covid-19 death were detected in 24 hours, a jump from an average daily rate of around 1,300 infections recorded last week.

Health Minister Joe Phaahla described the rise in infections was "worrying", adding that the situation was being monitored.

"We hope that even if there is rise, it will not be disruptive," he said.

More than half of the new cases reported were found in the province of Gauteng, where Johannesburg is situated.

Italy reports 70,520 coronavirus cases today, 143 deaths

Italy reported 70,520 Covid-19 related cases today, against 73,212 yesterday, the health ministry said, while the daily number of deaths fell to143 from 202.

Italy has registered 162,609 deaths linked to Covid-19 since its outbreak emerged in February 2020, the second-highest toll in Europe after Britain and the eighth highest in the world.

The country has reported 16.1 million cases to date.

Patients in hospital with the virus - not including those in intensive care - stood at 9,914 today, down from 10,076 a day earlier.

There were 43 new admissions to intensive care units, decreasing from 46 yesterday. The total number of intensive care patients stood at 409, edging down from a previous 411.