While vaccination drives have brought down infections in numerous – mostly wealthy – countries, the rise of the delta variant, which first emerged in India, has stoked fears of new waves of a virus that has already killed nearly 4 million people.

Bangladesh announced that it would impose a new national lockdown from Monday due the variant, with offices shut for a week and only medical-related transport allowed.

Sydney's normally bustling harborside center was nearly deserted after people were ordered to stay home except for essential trips.

New Zealand, citing "multiple outbreaks" in Australia, announced a three-day suspension of its quarantine-free travel arrangement with its larger neighbor.

COVID-19 Response Minister Chris Hipkins said the suspension would give officials time to consider measures "to make the bubble safer, such as pre-departure testing for all flights" between the two countries.

Sydney's new restrictions apply to some 5 million people, along with hundreds of thousands of others living in nearby towns.

Many are reeling from the shock of the sudden outbreak, in a city that had returned to relative normality after months with very few cases.

"We've been struggling to get back from the lockdowns of last year," said Chris Kriketos, 32, who works at a bakery in central Sydney.

"Today just feels like another kick while you're slowly getting up."

Globally, the pandemic is still slowing down, with the World Health Organization (WHO) reporting the lowest number of new cases worldwide since February and decreasing deaths attributed to COVID-19.

But concerns over the delta variant have prompted new restrictions in countries that had previously managed to bring the virus under control.

"There is currently a lot of concern about the delta variant," WHO chief Tedros Adhanom Ghebreyesus told a Friday press conference.

"Delta is the most transmissible of the variants identified so far, has been identified in at least 85 countries and is spreading rapidly among unvaccinated populations."

Russia's Euro 2020 host St. Petersburg on Saturday reported the country's highest daily COVID-19 death toll for a city since the start of the pandemic.

Official figures said the city, which has already hosted six Euro 2020 matches and is due to host a quarter-final next Friday, recorded 107 virus deaths over the last 24 hours.

Russia has seen an explosion of new cases since mid-June, driven by the delta variant, which has now spread to Europe.

Spain nonetheless brought an end to mandatory outdoor mask-wearing on Saturday, a year after the rule was first introduced during Europe's devastating first wave of the virus.

The decision came despite the announcement of a major coronavirus cluster in Madrid, traced to a student trip to the holiday island Mallorca, with more than 2,000 people ordered to self-isolate.

The Netherlands also ended its rules on outdoor mask-wearing, while easing restrictions on indoor dining and reopening nightclubs to people who have tested negative.

And Switzerland scrapped most of its remaining coronavirus restrictions on Saturday after Health Minister Alain Berset said this week that the country's use of Pfizer-BioNTech and Moderna vaccines gave adequate protection against the delta variant.

But delta is so contagious that experts say more than 80% of a population would need to be jabbed in order to contain it – a challenging target even for nations with significant vaccination programs.

While several studies have shown that vaccines are slightly less effective against delta, they are still highly effective – but only after the second dose.

Israel, which has one of the world's most successful vaccination campaigns, has seen infections linked to the variant surge since dropping a requirement to wear masks in enclosed public places 10 days ago.

After four days of more than 100 new cases a day, the health ministry reversed the decision.

The head of Israel's pandemic response task force, Nachman Ash, said the rising caseload was not yet matched by a parallel rise in hospitalizations or deaths.

Infections are also surging at an alarming rate in at least 12 countries in Africa, with the delta variant fueling unprecedented hospitalizations, the Africa Centers for Disease Control and Prevention has warned.

According to the WHO, only 1% of Africans are fully vaccinated – the lowest ratio globally.

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