Sandra do Rosaria is dressed in full protective gear -- gown, gloves, visor and mask -- as she talks to patients in a care home in Loures, a northern suburb of Portugal's capital Lisbon.

But she is not here in a medical capacity and is not visiting a relative either -- she is one of a team of municipal employees and volunteers helping residents to cast their ballot for Sunday's presidential election.

"We have to keep to the health guidelines, but also respect ballot secrecy. And that's not easy with some elderly people," do Rosario says as she explains the formalities to residents behind a floral curtain of a makeshift voting booth.

Even as Portugal battles an explosion in the number of Covid-19 infections, authorities are determined that thousands of voters around the country who are self-isolating or too weak or vulnerable to leave home should still be able to vote.

They will be allowed to fill out their ballots in their care facility, which will then be collected and taken to the polling stations.

"We need to combat the pandemic, but we mustn't suspend democracy," said Loures' communist mayor, Bernardino Soares, describing the logistics of the unprecedented operation as "very complicated".

He said it was "organised at the very last minute" and voters were allowed until last Sunday to sign up.

In all, some 13,000 people in Portugal who are forbidden from leaving their house or care home have applied to vote in this way.

And in Loures, a town of 200,000 people, some 245 voters who are self-isolating and about 20 more care home residents will participate in the scheme.

"I think it's good. You can still vote without going out, so it's the only way," said one resident called Ana.

Another, 85-year-old Ermelinda Mato says she too believes it is worth the trouble after watching her ballot being sealed in a blue envelope and placed in a box.

Restrictions and curfews have been in place in the hardest-hit regions in Portugal for the past two months.

But faced with a new upsurge in the pandemic, the government last week decided to impose a second general lockdown.

Portugal now has the highest number of infections in proportion to its population in the world after Gibraltar, according to an AFP tally.

On Wednesday, the number of daily infections jumped by nearly 50 percent to 14,647 and the number of daily deaths rose to 219, both new records over a 24-hour period, official data showed.

Despite the health emergency in place since November, Sunday's presidential election could not be postponed under national law.

Last Sunday, the authorities allowed voters to vote in advance. And of the close to 250,000 people who signed up, turnout was around 80 percent.

But long queues at the polling stations, particularly in Lisbon, might put off many voters and most observers are expecting a record number of abstentions or no-shows.

"If the abstention rate reaches 75 percent, and that's possible, it will be down to the pandemic," Antonio Costa Pinto, a political scientist at Lisbon University told AFP.

Most opinion polls suggest the current conservative President Marcelo Rebelo de Sousa will be re-elected in the first round, while the socialists have fielded no candidate at all.

And medical professionals are concerned that, in health terms, the election itself represents a "large risk" in possibly spreading the virus.

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