JOHANNESBURG — South Africa is struggling to cope with a spike in COVID-19 cases that has already overwhelmed some hospitals, as people returning from widespread holiday travel along the coast spread the country’s more infectious coronavirus variant.

Of particular concern is Gauteng province, the country’s most populous, which includes the cities of Johannesburg and Pretoria. Authorities say it is already seeing a spike in new infections after people traveled to coastal areas, where the variant is dominant.

“Gauteng is going to be hit very soon and very hard,” said Professor Willem Hanekom, director of the Africa Health Research Institute. “It is anticipated Gauteng will have a steep curve of increased cases and hospitalizations.”

The Steve Biko Hospital in the Pretoria area has already reached capacity and is putting COVID-19 patients into a field hospital outside the main building.

In response to the resurgence, South Africa has reimposed restrictions to curb the spread of the virus, including banning alcohol sales, closing bars, enforcing a night curfew and limiting attendance at public gatherings including church services and funerals.

President Cyril Ramaphosa is expected to address the nation Monday night on the pandemic.