British Columbia has identified another 10 cases of the U.K. and South African coronavirus variants in recent days, bringing the provincial total to 28 infections.

The latest numbers were released Friday by provincial health officer Dr. Bonnie Henry, who expressed concerns that the COVID-19 variants could cause a spike in cases.

"These variants have lead to increased transmission in some areas of the world – we see that in the U.K. and places like Portugal and Ireland – so it is very concerning for us," she said during a modelling presentation.

Henry stressed the importance of being able to "manage and prevent repeated importations of these types of variants." She also extended the province's ban on social gatherings and events once again.

British Columbia has now identified 19 cases of the U.K. variant known as B.1.1.7 and nine cases of the South African variant known as B.1.351. That's up from a combined total of 14 cases of the two variants on Monday.

Five of the U.K. variant cases were acquired locally, but Henry said they were all close contacts of recent travellers who are believed to have caught the disease overseas.

Eight of the South African variant cases were also acquired locally, but only three involved close contacts of a traveller. Health officials have not been able to determine the source of the other five.

"This is more concerning to us," Henry said. "We are stepping up our surveillance and targeted surveillance to better understand where we are."

To weed out variant cases, B.C. has conducted genome sequencing on roughly 4,500 coronavirus cases since the start of December.

Health teams have been doing random sampling in areas where COVID-19 infections are increasing, as well as targeted testing of specific demographics and testing of every confirmed case involving a traveller who arrived in B.C. from an international destination.

Beyond fears that the mutations could spread more easily, the provincial health officer noted there are concerns "some vaccines may not work as well" against the B.1.351 variant.

Last week, health officials in Ontario shared new modelling that suggests the U.K. variant will likely be the dominant strain in the province by March – a troubling forecast that could force the government to reassess its approach to containing the spread.

"The new variants give us less room to relax and less room for error," Dr. Adalsteinn Brown, co-chair of the province's COVID-19 science table, said at the time.

The modelling still indicated Ontario's downward trend in cases could continue if it maintains its public health measures.