Coronavirus infections were surging across the globe on Wednesday, forcing several countries to put the brakes on reopening or impose new restrictions on their weary populations.

The number of COVID-19 cases worldwide topped 13.4 million and more than 581,000 deaths have been reported since the virus emerged late last year in China.

With the situation predicted to worsen in the United States, Walmart, the world's largest retailer, said it would require customers to wear masks at all its stores to help stop the virus spreading.

Venezuela, four days after announcing a loosening of restrictions, became the latest country to reimpose localized lockdown measures, including a "radical quarantine" in the capital Caracas; while Bolivia's La Paz department said it would undergo a four-day total quarantine.

Latin America topped 150,000 deaths Wednesday, becoming the world's second hardest-hit region after Europe, where a total of 203,793 people have died.

Brazil accounted for roughly half of Latin America's deaths, with more than 1,200 new fatalities recorded Wednesday bringing the total toll since the outbreak began there to 75,366.

In Ireland, Prime Minister Micheal Martin delayed the end of the lockdown because of a surge in new cases, with restrictions to remain in place until August 10 and the government also mandating the wearing of masks in shops.

The United States meanwhile set a new record Wednesday with more than 67,000 cases registered in the previous 24 hours. 

The country has the world's highest death toll at more than 137,000 fatalities, and officials are scrambling to roll back reopenings that were meant to revive economies.

- 'Let's stop this nonsense' -

The latest research models show the number of US deaths projected to rise to over 150,000 by next month. 

"We've got to almost reset this and say, 'Okay, let's stop this nonsense," Anthony Fauci, the top US infectious disease expert, told The Atlantic.

In the US state of Oklahoma, the Republican governor, Kevin Stitt, who has often declined to wear a mask, said he had tested positive for COVID-19.

The use of masks to slow the spread of the virus has become a political flashpoint in the US, where Trump had resisted wearing one until recently and at times mocked the trend.

Stitt's state recorded a single-day record of 1,075 new cases, while its neighbor to the south, Texas, reported 10,791 new cases and 110 new fatalities -- both "new highs."

Cases and death tolls continue to mount across the United States, particularly in the south and west, with Florida and California also hard hit.

Walmart meanwhile said it will require shoppers at its more than 5,300 stores to wear masks starting on July 20, joining a growing group of US businesses in mandating the protection.

"We know this is a simple step everyone can take for their safety and the safety of others in our facilities," Walmart's US chief operating officer Dacona Smith said.

- Vaccine candidate trials -

Amid the grim forecasts, American biotech firm Moderna said it would start the final stage of human trials for its vaccine candidate on July 27, after promising results from earlier testing.

Moderna is considered a leader in the global race to find a vaccine, and while its study should run until October 2022, preliminary results should be available long before then.

In the Asia-Pacific region, which had been somewhat successful in fighting the pandemic, there was fresh evidence of the deadly threat still posed by the virus.

Hong Kong's bars, gyms, and beauty salons closed again Wednesday and a ban on gatherings of more than four people came into force as the city battled a fresh outbreak.

There was alarm in Japan too, where Tokyo's governor warned that the capital was on its highest virus alert level after a spike in infections.

That came after the Indian state of Bihar, with a population of around 125 million, announced a 15-day virus lockdown starting Thursday.

- 'Please stop' -

Authorities in Australia, meanwhile, pleaded Wednesday with the public to heed social distancing guidelines, with roughly five million people in Melbourne in lockdown since last week in a bid to contain a new outbreak.

"A particular concern for us is the ongoing parties and gatherings," said Rick Nugent, acting assistant commissioner of Victoria state. "Please stop."

Face masks will also become compulsory in England's shops from next week, while in South Africa, where the number of cases topped 300,000, a nationwide curfew was reimposed.

On Thursday Spain will honour its 28,400 victims at a state ceremony to be attended by top EU and World Health Organization figures. The country is already seeing a surge in cases barely three weeks after coming out of lockdown.

Venezuela tightens anti-virus measures

Venezuelan President Nicolas Maduro has announced a tightening of coronavirus containment measures in the capital Caracas and neighboring Miranda state to try to halt the spread of the deadly disease.

The country was one of the least affected in Latin America in the early stages of the pandemic but has seen an alarming rise in cases and deaths in recent weeks.

It took 70 days for Venezuela to record its first 1,000 COVID-19 cases -- but just three days to go from 7,000 to 8,000 cases.

This week Venezuela surpassed 10,000 officially confirmed infections, although the opposition and organizations such as Human Rights Watch believe the true numbers are much greater.

"Due to the increase in COVID-19 cases, because of the illegal entry of people into the country... I've taken the decision to apply a radical quarantine in Caracas and Miranda state," Maduro said Wednesday on Twitter.

US cases skyrocket

The number of new coronavirus cases and fatalities continued to mount across the United States on Wednesday, with Texas and Oklahoma recording new highs.

Johns Hopkins University, which tracks the spread of the disease, said late Wednesday that 67,632 new cases of the disease had been reported across the country in the previous 24 hours, a new national record.

The Texas Department of State Health Services reported 10,791 new cases and 110 new fatalities, saying in a tweet that both numbers "are new highs" for the state.

Oklahoma -- where the governor, Kevin Stitt, announced Wednesday he had tested positive for the virus -- recorded 1,075 new cases, a single-day record.

And Alabama also hit a grim milestone, recording 47 deaths, the highest in one day.

The disease has also been spreading rapidly in other states, notably Florida, which has recorded nearly 302,000 cases of coronavirus since the pandemic began.

California has also seen a surge in recent weeks, prompting officials to reimpose lockdowns.

The state reported its second highest single-day increase in coronavirus cases and deaths on Wednesday, with 11,125 new cases and 140 additional deaths.

"We are in an alarming and dangerous phase in this pandemic here in L.A. County," said Barbara Ferrer, the Los Angeles County Department of Public Health director, as she announced 44 additional deaths from the virus on Wednesday and 2,758 new cases.

"These alarming trends reflect behaviors from three weeks ago," she added, saying that the county was seeing the highest rates of hospitalizations since the beginning of the pandemic.

She said there were currently 2,193 people hospitalized in the county due to the virus.

"Younger people are being hospitalized at a faster rate than ever before," Ferrer said.