According to the latest school guidelines published by the California Department of Public Health, “COVID-19 is mostly spread from person-to-person in the air through virus-containing droplets in the breath of someone with COVID-19.” A person with COVID-19 is considered contagious two days before their symptoms start until at least ten days later, fever is gone 24 hours, and symptoms have improved.
If a person with COVID-19 has no symptoms, they are considered contagious 2 days before their positive test until 10 days after the positive test.
If a person who was initially asymptomatic develops symptoms after testing positive, the contagious period should be considered as two days before the test date and is extended to ten days after the onset of symptoms.