Their vaccination data wasn't submitted. There is no way to know who was vaccinated and who wasn't.
https://www.hollywoodreporter.com/news/whooping-cough-outbreak-hits-la-private-school-harvard-westlake-1190769
Plus, just because the unvaccinated didn't get sick doesn't prove a thing. Not every student was in the same class, and the outbreak was spread across two campuses. Plus you have to take into account who the students were around outside of school.
Unless and until all that information is compiled and released, you're just masturbating over conjecture and rumor.
What did the bible say about bearing false witness?