They’ve also identified the variants first found in the U.K. and in South Africa in the samples they’ve tested and there’s one specific issue researchers worry about the most right now. “There is concern that the current vaccine may not be effective against the South African variant,” said Kenji. “Most specifically, the Oxford astrazeneca vaccine.” That variant’s now been found in adults in both Santa Clara and Alameda counties. On Thursday, Alameda County health officials wouldn’t share any information about the infected person there, but Santa Clara health officials say the sick person in their county quarantined after an international trip so exposure to others may be low.