students. >> when we look at other immunization requirements-- polio, rubella, hepatitis-- that we've had in schools for generations, we are going to see other districts follow l.a. unified's lead. >> i have a number! >> reporter: the nation's second largest school system will now require kids 12 and older to get vaccinated by thanksgiving, if they want to attend in-person classes. board member nick melvoin says too many school administrators are overwhelmed. what has their workload been like through covid thus far? >> well, according to this principal, about 90% of his schedule over the last month of school has been covid protocols. we're already seeing, in instances where kids are vaccinated, that we can go back to a normal school day. >> reporter: los angeles county has recorded more than 190,000 covid cases in kids 17 and under since the start of the pandemic. they now join culver city, california and hoboken, new jersey school districts, which already enacted vaccine or testing mandates for students and staffers.