STAT recently spoke to Erica Pan, California’s state epidemiologist, about what public health officials are doing to monitor for human H5N1 infections. The conversation, which took place before California announced its human cases, has been lightly edited for clarity and length.

Both patients were dairy workers whose illnesses were mild. Investigators are continuing to evaluate the contacts of a Missouri patient who had no exposure to animals.

Hospital workers reported respiratory symptoms after encountering a Missouri patient with H5N1 who had not been exposed to farm animals. Officials say bird flu transmission is unlikely.