ROME — Pope Francis apologized to the faithful Wednesday for not being able to greet them and shake their hands as Italy posted a record spike in coronavirus infections that is threatening to once again spiral out of control.

Instead of wading into the crowd to embrace the sick and kiss babies during his weekly general audience Wednesday, Francis walked in through a back door directly onto the stage to begin his catechism lesson.

At 83 and with part of a lung removed when he was in his 20s due to illness, the pope would be at high-risk for COVID-19 complications. And yet he has been reluctant to wear a face mask and appeared without one again Wednesday, even though many of his entourage and all of the Swiss Guards were using them.

He told the crowd Wednesday: “I would like to come down as usual and get close to you to greet you, but with new prescriptions, we would better keep our distances.”

Francis often seems out of breath and speaks in a whisper because of his lung condition, suggesting that wearing a mask might be particularly uncomfortable for him.

This week, four Swiss Guards tested positive for COVID-19 and were in isolation. All told there have been 19 cases in the Vatican, and the tiny city state amended its mask mandate last week to conform to that of Italy to require them indoors and out.

Italy is seeing a sharp resurgence in COVID-19 cases, with the Lazio region around the Vatican among the worst-hit in this new wave of the pandemic, with more people in the hospital than any other region.

On Wednesday, the country as a whole recorded its single biggest single-day jump in infections since the start of the outbreak, adding another 7,332 cases.

Public health officials are warning that hospitals are starting to fill up and Italy’s contact-tracing system is starting to crumble under the weight of the new infections.

“No health system is able to do contact tracing for more than a few thousand infections,” said virologist Andrea Crisanti, who as a regional adviser was credited with helping to keep Veneto’s infections down during the peak of Italy’s outbreak with aggressive testing and tracing.

Speaking to RAI TG24 on Wednesday, Crisanti said the spike threatened to create a “vicious circle” of too many infections to trace, allowing the virus to spread uncontrolled. He suggested that a Christmastime lockdown would help stop the chain of transmission and give enough breathing room to “reset” the contact tracing system.