On a visit to a school in central England, Mr Johnson thanked students for enduring months at home because of the outbreak, which he said had helped the country get the disease under control.
"The risk to your health is not from Covid because after all, statistically speaking, your chances of suffering from that disease are very, very low," he said.
"The greatest risk you face now is of continuing to be out of school."
The new guidance advises secondary school students aged between 11 and 18 along with staff to wear face coverings in corridors and communal areas, in places with local coronavirus restrictions.
Some 41,500 people have died in the coronavirus outbreak in Britain - the worst death toll in Europe - and the government response to the pandemic has been criticised.
France records virus spike
French health authorities on Wednesday reported more than 5,000 new coronavirus cases for the previous 24 hours, hitting their highest figure since May days before children return to school nationwide.
The daily figure has topped 4,000 several times in recent days, ahead of the 1 September return to school for millions of students.
The French public must act in "a spirit of responsibility" to limit the surge in new cases, Prime Minister Jean Castex said on France Inter radio on Wednesday morning.
"The state has its share of responsiblity... but everyone has to feel like it's their job to fight the pandemic," Mr Castex added.
On Monday, German health authorities labelled the Ile-de-France region including capital Paris and the Provence-Alpes-Cote d'Azur region around Mediterranean port city Marseille "risk zones" for the virus.
Davos summit suspended
The World Economic Forum said on Wednesday it would postpone its 2021 Davos summit for several months to reduce any risks to participants from the coronavirus pandemic.
Next year's gathering of the world's political, economic and business elite may not even take place against its traditional idyllic snowy backdrop of the Swiss Alpine village of Davos, the organisation hinted.
Rather than January as usual, the event will take place "early next summer," WEF spokesman Adrian Monck said in a statement.
"The decision was not taken easily, since the need for global leaders to come together to design a common recovery path and shape the 'Great Reset' in the post-COVID-19 era is so urgent," he said.
"However, the advice from experts is that we cannot do so safely in January."
Berlin protest banned
The city of Berlin on Wednesday has banned a planned weekend protest against coronavirus rules, drawing outrage from the far-right AfD party and spurring calls for "resistance".
City authorities cited health concerns as the reason for their decision not to allow Saturday's demo, saying they feared participants would not adhere to hygiene precautions like keeping the required 1.5 metres apart.
Organisers of the demo, who said some 20,000 people were planning to attend, said the decision was politically motivated and vowed to have the ban overturned by a court.
A previous "anti-corona" demonstration on 1 August in the German capital attracted thousands of people, a mixture of the hard left and right, anti-vaccination campaigners, conspiracy theorists and self-described "free thinkers".
Police broke up the protest early after demonstrators failed to comply with coronavirus prevention rules such as wearing face masks and keeping a safe distance.
"This is not a decision against freedom of assembly, but for protection against infection," Berlin's state interior minister Andreas Geisel said.
Supporters of the demonstration flooded the organisers' Facebook page with calls for "resistance" and pledges to turn up in Berlin on Saturday anyway.
Germany's top-selling Bild daily condemned the ban, saying it would make "martyrs" of the demonstrators who oppose the government's coronavirus restrictions and the measures put in place to curb the spread of Covid-19.
Germany has fared better than many of its European neighbours during the pandemic but infection rates have risen this month to levels not seen since April.
The Robert Koch disease control institute on Wednesday reported a total of 236,429 COVID-19 infections since the start of the pandemic, up 1,576 on the previous day, with a total of 9,280 deaths.
People in Australia must stay at least 1.5 metres away from others. Check your state’s restrictions on gathering limits.
If you are experiencing cold or flu symptoms, stay home and arrange a test by calling your doctor or contact the Coronavirus Health Information Hotline on 1800 020 080.
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