All teachers in the US state of California will have to be vaccinated against Covid-19 or submit to weekly virus tests, the governor has announced, as authorities grapple with rapidly increasing infection rates.

The number of people testing positive for the disease has surged across the United States in recent weeks, with the highly infectious Delta variant blamed for the bulk of new cases.

That has worried parents and educators as the most populous state in the country prepares to send its largely unvaccinated children back into classrooms for the new school year.

"To give parents confidence that their children are safe as schools return to full, in-person learning, we are urging all school staff to get vaccinated," Governo Gavin Newsom said.

"Vaccinations are how we will end this pandemic. As a father, I look forward to the start of the school year and seeing all California kids back in the classroom."

As it was for many children around the world, last school year in California was badly interrupted, with classes moved online, and many children without adequate internet connections missing out on huge chunks of their education.

Along with the rest of the country, the state managed to tame the worst of its coronavirus outbreak earlier this year and life is largely back to normal.

But the return to in-person learning for this academic year has been put at risk by growing infections; more than 10,000 new cases are being recorded every day in the state - a ten-fold increase over two months.

Doctors say these infections are chiefly among the unvaccinated.

Vaccinations are free and widely available in the United States.

The order - the first such state-wide mandate in the country - applies to public and private schools, and puts the onus on administrators to ensure either that staff are fully vaccinated, or that they undergo Covid-19 tests at least once a week.

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Around two-thirds of Californians over the age of 12 have been fully vaccinated, according to the state's health department.

Children under that age are not eligible for the shots.

Finland tightens restrictions as infections hit new daily record

Limits on public gatherings will be tightened in the Finnish capital Helsinki as the country's infection rate hit a new daily high, health chiefs have said.

The total of 1,024 new cases beat a peak hit in March this year, driven by the highly contagious Delta variant, according to the Finnish Institute for Health and Welfare. Hospital admissions also increased.

Prime Minister Sanna Marin announced plans a week ago to make Finns show proof of vaccination before visiting restaurants and other leisure services, as well as to start vaccinating 12- to 16-year-olds.

While Finland remains among the countries least affected by the pandemic, infections began to rise in June and accelerated further in July when soccer fans returned home from Euro 2020 matches abroad.

To date, the nation of 5.5 million people has recorded 109,983 cases and 995 deaths. There are currently 83 people in hospital with Covid-19.

More than 82% of Finns have now received at least one vaccine dose and more than 48% are fully vaccinated against the coronavirus, according to data from the European Centre for Disease Prevention and Control.

Israel requires tests for children aged three and up

Israel is to require Covid-19 tests from next week for children as young as three to enter schools, swimming pools, hotels or gyms as infections surge despite extensive adult vaccinations.

The country already required children aged 12 and over to show a Green Pass reintroduced late last month showing a person's vaccination and testing status and whether they had recovered from the disease.

Prime Minister Naftali Bennett said that, from next Wednesday, Israel would fund unlimited tests for children aged three to 11.

He also said that Israel was also considering lowering the age limit for its campaign of booster vaccinations, currently offered only to those aged 60 and over.

Meanwhile, Israel has announced mandatory quarantine for travellers, vaccinated or not, arriving from most countries of the world beginning on Monday.

A country of nine million inhabitants, Israel was one of the first to launch a nationwide vaccination campaign in December, thanks to an agreement with the pharmaceutical giant Pfizer.

It saw infection rates plummet, which allowed Israel to resume an almost normal routine, with schools, bars and concert venues open.

However, the more contagious Delta variant of the virus has driven a rise in cases to levels not seen since February.

The health ministry reported 5,946 new cases today. In total, it has counted 921,083 cases and 6,593 deaths since the pandemic started early last year.

Japan health adviser wants stricter virus measures

Japan's top health adviser Shigeru Omi has said he will request stricter emergency measures for about two weeks to tackle a spike in coronavirus cases in Tokyo and other areas.

Japan's capital reported 4,989 new daily infections today.

Mr Omi called on the government to expand testing to deal with the surge in cases and said the pandemic "needs to be treated as a natural disaster".

Russia reports record-high 808 Covid-19 deaths

Russia has reported a record-high 808 coronavirus-related deaths in the last 24 hours and 21,932 new cases, including 2,294 in Moscow.

Russia's daily reported cases have gradually dipped from a peak last month that authorities blamed on the infectious Delta variant and a slow vaccination rate.