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Portugal's official daily number of new COVID-19 cases on Monday dropped below 1,000 for the first time since early October, amid a national lockdown and just weeks after it was the worst-hit country in the world by size of population.

The lockdown that began Jan. 15 has brought "a very steep drop" in new cases, André Peralta Santos of the General Health Directorate told a televised meeting of health experts and .

The 14-day incidence rate of new cases per 100,000 people has fallen to 322. At the end of January, it was 1,628.

The country's so-called "R" number, showing how many people each person with COVID-19 infects, is around 0.67—the lowest in Portugal since the pandemic began and currently the lowest in Europe, according to Baltazar Nunes of state laboratory INSA.

Testing for COVID-19 has been erratic, though, and total tests have fallen from more than 70,000 a day at the end of last month to around half that over the past week.

The current lockdown period expires on March 1, but it is widely expected to be extended.

Portugal on Monday reported fewer than 600 new COVID-19 cases. At the end of January, it was reporting more than 16,000 a day, with experts blaming the surge on a four-day relaxation of restrictions over Christmas and the appearance of a virus variant first identified in southeast England.

Hospital admissions have dropped from almost 7,000 a day at the start of the month to fewer than half that number. The country's intensive care units had more than 900 patients in early February and now are looking after 627.

Experts warned, however, that variants remain a threat and that loosening restrictions too quickly could trigger another surge.

Authorities say the variant first found in England accounts for around 48% of Portugal's COVID-19 cases.

On Sunday, authorities reported seven cases of a variant first identified in Manaus, Brazil, which is highly contagious and may be able to infect people who previously have had COVID-19.

More than 150,000 Brazilians live in Portugal, and the two countries have close cultural and economic ties.

But the seven cases are limited to two, interlinked families and stem from just one arrival in Portugal.

"That's good news," João Paulo Gomes, an INSA researcher, told the meeting.