Labour is calling for a return to hybrid parliamentary proceedings as England re-enters coronavirus lockdown.
It comes after several unions representing Parliament's staff wrote to Leader of the House Jacob Rees-Mogg asking him to allow MPs to vote online.
They say a return to the hybrid model would "reduce the very real risk of a widespread outbreak in Westminster".
Mr Rees Mogg said it was important that MPs were present to properly scrutinise the government.
Shadow Leader of the House Valerie Vaz said some MPs are "excluded from voting" when they are complying with coronavirus rules. "That is not only bad for their constituents but bad for democracy," she said.
Referring to the online voting system used in the previous lockdown, Ms Vaz said: "There is one simple way of dealing with this and I ask the Leader of the House to think very seriously in this very grave time that we go back to remote voting."
Mr Rees Mogg said measures were already in place to allow MPs who cannot attend Parliament to vote by proxy. He said the measures "had the consensus across the House."
Some MP have been granted a proxy - when another MP votes on their behalf - because they are clinically vulnerable to the virus.
Mr Rees Mogg said he was hoping to expand proxy voting to all members, regardless of whether they can attend Parliament.
But he added that it was "important that members are here" because they have to ensure that coronavirus legislation is properly debated, that constituency issues can be raised, and Brexit legislation is introduced by the end of the transition period on 31 December.
He said that the full range of parliamentary activities had not been possible under the earlier fully-hybrid proceedings.
Earlier on Monday, a group of trade unions wrote to Mr Rees Mogg expressing concern for parliamentary staff.
The letter, sent by Ken Gall, the president of the Trade Union Side, adds: "The current arrangements, which require greater physical attendance by MPs, their staff and parliamentary employees, have already caused concerns - including among some MPs - about potential risks.
"Figures also show that the number of staff with Covid sickness absence are rising and staff - having seen the government taking prompt action in response to rising cases nationally - will expect Parliament to respond similarly."
According to Parliament's website, the Trade Union Side exists in the House of Commons to provide effective industrial relations.
Garry Graham, deputy general secretary of Prospect, which represents some of Parliament's professional staff, said: "Requiring MPs to travel to Westminster just so they can vote in person is ludicrous.
"Not only is it encouraging unnecessary travel across the country, it means more staff are required to commute into the Parliamentary estate every working day."
He added: "Thanks to the hard work and expertise of our members hybrid proceedings worked well during the last lockdown and there is no reason they can't again."
Mr Graham warned that failing to return to the hybrid model "risks infections getting so high that Parliament has to shut altogether. It's time for Jacob Rees-Mogg to put the safety of parliamentary staff first and return to hybrid operations, including remote voting, while it is still an option."
The general secretary of the PCS union, which also represents some parliamentary staff, echoed the sentiment.
Mark Serwotka said a failure to bring back the hybrid model would "show the government has scant regard for the health and safety of parliamentary staff who keep our democracy running."