Health authorities have registered a surge in new COVID-19 infections in Portugal, the United Kingdom and parts of the Americas.
Coronavirus cases in Portugal jumped by 2362 in the past 24 hours, the biggest increase since mid-February, official data showed on Wednesday, as authorities scrambled to stop the spread of the more contagious Delta variant.
Portugal, with a population of 10 million, faced its toughest battle against the coronavirus in January but a recent surge in cases brought daily numbers to levels last seen in February, when the country was under a strict lockdown.
Daily coronavirus deaths, in single digits, remain well below February levels, however.
The first cases of the Delta variant were registered in Portugal in April and now it accounts for more than half of cases in the country, which has the European Union's second highest seven-day rolling average of cases per capita.
In total, Portugal, which has fully vaccinated around 31 per cent of its population, has recorded 879,557 cases and 17,096 deaths since the pandemic began.
Most new cases are in Lisbon.
Authorities are speeding up vaccinations and have imposed new restrictions in a few municipalities, including in the Lisbon area.
The UK recorded a further 26,068 cases of COVID-19 on Wednesday, the highest daily figure since January 29 and sending the seven day-tally up 70 per cent on the week before, official data showed.
Despite the surge in new infections, the UK's daily fatality figures have remained in low double digits.
Fourteen deaths were reported on Wednesday, down from 23 the day before.
That compares with the more than 1000 fatalities that were repeatedly reported per day at the height of the UK's worst wave in the pandemic, in January this year.
Scientists have said the trend suggests the rapid vaccine roll-out has weakened the link between infections and deaths.
The seven-day tally for people being admitted to hospital was up 6 per cent to a daily figure of 263.
The data showed that 84.9 per cent of adults have had a first vaccine while 62.4 per cent have had both.
Cases of the virus are declining in North America but in most of Latin America and the Caribbean the end to the coronavirus pandemic "remains a distant future," the Pan American Health Organisation (PAHO) director Carissa Etienne said on Wednesday.
While infections in the United States, Canada and Mexico are falling, in Latin America and the Caribbean just one in ten people have been fully vaccinated against COVID-19, "an unacceptable situation," she said in a briefing.
Etienne warned that the hurricane season in the Caribbean is arriving at a time when outbreaks are worsening and she urged countries to outfit hospitals and expand shelters to reduce the potential for transmission.
The World Health Organisation has reiterated its longstanding recommendation that everyone wear masks to lessen the spread of the coronavirus.