COVID-19 live updates: 'Extremely unlikely' virus came from Chinese lab, WHO says

Some classes at the University of North Carolina have the option to go virtual for nearly two weeks after school officials received hundreds of complaints following Saturday night's crowd that rushed Franklin Street.

"As you are no doubt aware, last night hundreds of Carolina fans -- many, presumably students -- flooded Franklin Street to celebrate our men’s basketball victory over Duke," UNC-Chapel Hill officials said in a statement Sunday.

UNC-Chapel Hill students have agreed to adhere to COVID-19 rules like state gathering restrictions, mask-wearing and physical distancing, according to university officials.

"Those standards do not include exceptions for winning basketball games," the officials said.

The timing of the crowd fell the weekend before students returned for in-person learning for spring semester. While in-person instruction will continue Monday, faculty are allowed to teach virtually and return to in-person learning on Feb. 17, according to the university. Students who attend in-person classes are required to be tested twice a week.

ABC News' Will Gretzky contributed to this report.

The South African government halted its rollout of a COVID-19 vaccine developed by England's University of Oxford and British-Swedish pharmaceutical giant AstraZeneca, following trial results that found the shot provided "minimal protection" against mild-to-moderate sickness from a new, more contagious variant of the novel coronavirus spreading in South Africa.

The trial did not assess whether the Oxford/AstraZeneca vaccine protects against severe illness and death caused by the new variant, known as B1351.

An AstraZeneca spokesperson said the company believes its vaccine will protect against severe disease caused by B1351.

"This was a small study with predominantly young (average 31 years) healthy adults, where severe disease is not predominant. No severe disease or hospitalization was observed in the vaccine or control participants," the spokesperson said in a statement Monday. "We are working closely with the South African Ministry of Health on how best to support the evaluation of COVID-19 Vaccine AstraZeneca against severe disease of the B.1.351 variant, and how to bring this vaccine to the South African people."

ABC News' Zoe Magee contributed to this report.