Coronavirus updates: Trump says 'not much' he'd change about COVID response

In a bid to speed up the race to find a vaccine for the novel coronavirus, the U.K. government announced Tuesday morning that it will be launching some controversial vaccine studies known as challenge trials.

In a world first for COVID-19, young healthy volunteers will be vaccinated, then intentionally exposed to the potentially deadly virus in order to test vaccines in a controlled environment. Although some medical experts view them as ethically questionable, the benefit of challenge trials is that they can be completed in a much shorter timeframe than typical late-stage studies.

The experiment will take place in a quarantine ward of a hospital in north London. After inhaling a diluted dose of the virus, the trial participants will be closely monitored, thus enabling scientists and doctors to better understand the disease and how a vaccine can fight it.

"Human challenge studies can increase our understanding of COVID-19 in unique ways and accelerate development of the many potential new COVID-19 treatments and vaccines," said Dr. Chris Chiu of Imperial College London's Department of Infectious Disease, a lead researcher on the human challenge study.

ABC News' Zoe Magee contributed to this report.

The Italian region that was once the epicenter of the coronavirus pandemic will soon impose a nightly curfew, following a sharp rise in infections.

A curfew from 11 p.m. to 5 a.m. local time is expected to begin in Italy's northern Lombardy region on Thursday night and last until at least Nov. 13. All residents must stay home during this period, unless for reasons of health, work or necessity. Non-food shops and retail centers will also be shut on weekends.

Lombardy's regional government received authorization on Monday from Italian Health Minister Robert Speranza to implement more restrictive measures.

The move comes after Italy reported 10,010 new cases of COVID-19 last Friday, the country's highest daily tally since the start of its outbreak, shattering a previous record of 8,804 set last Thursday. Lombardy had the greatest number of cases of any other region that day, at 2,419.

Overall, Italy has confirmed at least 423,578 cases with 36,616 deaths since the start of the pandemic, according to the latest data from the country's civil protection agency.

ABC News' Phoebe Natanson contributed to this report.

Colombian cyclist Fernando Gaviria has been withdrawn from the Giro d’Italia after testing positive for COVID-19, his team said in a statement Tuesday.

It's the second time Gaviria has tested positive for the disease, after contracting it in March.

All other riders and staff members on Gaviria’s UAE Team Emirates had negative test results but will be tested again Tuesday.

"Gaviria was immediately isolated following the test result and is feeling well and is completely asymptomatic," the team said in the statement.

Gaviria, who has won five stages at the Giro d'Italia during his career, is not the first to withdraw from the annual road cycling stage race due to COVID-19. Dutch rider Steven Kruijswijk, Britain's Simon Yates and Australia's Michael Matthews were all forced to pull out last week after testing positive.

The Giro d'Italia, the second Grand Tour of 2020 after the Tour de France took pace between August and September, kicked off on Oct. 3 after initially being postponed due to the coronavirus pandemic. The race concludes on Oct. 25.

A COVID-19 outbreak at a privately-owned nursing home in northwestern Kansas has killed at least 10 residents, officials said.

All 62 residents at the Andbe Home in Norton, a four-hour drive from Wichita, have tested positive for COVID-19. Ten have since died, one remains hospitalized and the other 51 are being cared for at the nursing home, according to a press release from the Norton County Health Department.

Some staff members have also tested positive for COVID-19 and the remaining staff are being tested. The Norton County Health Department said it has been working with the Andbe Home, Norton County Hospital and the Kansas Department of Health and Environment regarding the outbreak.

"Steps are being taken to prevent any further outbreak including quarantining residents in their room and not allowing outside visitors into the facility," the agency said in Monday's press release. "Family members of the residents have been notified."

Northwestern Kansas has been hit hard by the coronavirus pandemic in recent weeks, and Norton County had the greatest number of new cases per 100,000 residents of any county in the United States for the two weeks ending Sunday, according to data collected by Johns Hopkins University.

Cases in Norton County, which is home to some 5,400 residents, increased from 46 two weeks ago to 340 as of Monday, according to data from the Kansas Department of Health and Environment.