During a press conference Wednesday, Governor Gavin Newsome announced that the South African strain of the coronavirus had been identified in California:

Newsom said one of the cases was found in Alameda County and the other in Santa Clara County. He did not share any additional information on those who tested positive or how they may have contracted the variant, called B.1.351. Newsom said the cases of the South Africa variant had been reported “as of a few hours ago.”

Since Newsom didn’t offer many details, we don’t know if the people who have this strain had recently traveled overseas or not. That would be important to give a sense of whether or not these are isolated cases or evidence that the strain is already being spread in the community.

The concern about the South African strain is based on two things. First, like the UK strain, it seems to spread around 50% faster than the original strain. But the real concern is that unlike the UK variant the South African strain is more resistant to at least some of the existing vaccines. This Sunday the health minister for South Africa announced that a plan to rollout the AstraZeneca vaccine was being put on hold because it’s not clear how effective the vaccine is against the variant:

Early data released Sunday suggest two doses of the Oxford/AstraZeneca Covid-19 vaccine provided only “minimal protection” against mild and moderate Covid-19 from the variant first identified in South Africa.

The study, which has not been released, included about 2,000 volunteers who were an average of 31 years old; about half received the vaccine and half received a placebo, which does nothing.

Viral neutralization against the B.1.351 variant was “substantially reduced” when compared to the earlier coronavirus strain, researchers said in a news release.

There are two caveats to these results. First, this comes from a pre-print study which hasn’t been peer-reviewed yet. Second, the study only looked at people with mild or moderate cases. That’s significant because it’s possible the vaccine is still effective in more severe cases. If so, it could be effective at reducing hospitalization and death rates even if it doesn’t do a great job reducing the infection rate.

A second vaccine developed by Novavax was also found to be less effective against the South African strain. Trials showed the vaccine was 89% effective in the UK but only 60% effective in South Africa.

Neither the AstraZeneca vaccine or Novavax are being used in the U.S. The Moderna and Pfizer vaccines that are approved and being used here appear to also be somewhat less effective against the South African variant. However, a spokesman for BioNTech, the company that co-developed the vaccine with Pfizer, said it would be possible to adjust the current vaccine in a matter of weeks:

Moderna and Pfizer-BioNTech both said their vaccines were effective against new variants of the coronavirus discovered in Britain and South Africa. But they are slightly less protective against the variant in South Africa, which may be more adept at dodging antibodies in the bloodstream…

Dr. Ugur Sahin, the chief executive of BioNTech, said in an interview on Monday that his company was talking to regulators around the world about what types of clinical trials and safety reviews would be required to authorize a new version of the Pfizer-BioNTech vaccine that would be better able to head off the variant in South Africa…

BioNTech could develop a newly adjusted vaccine against the variants in about six weeks, he said.

That sounds hopeful but it probably won’t take much more than six weeks for the more contagious South African variant to become a dominant strain spreading in communities around the country. Given that it has already been identified in three states, chances are good we’ll all be facing the possibility of catching this particular strain before long.

Here’s Gov. Newsom’s announcement today about the variants present in California: