SAN JOSE, Calif. — U.S. Health Secretary Xavier Becerra defended federal COVID isolation guidelines Monday that California earlier this month announced it was deviating from to shorten the amount of time people who test positive should stay home — a change that so far hasn’t led to a new spike in cases. California officials earlier this month shortened the recommended isolation period following a positive COVID-19 test from five days to one — 24 hours without fever. But the Centers for Disease Control and Prevention continues to recommend that people who test positive for COVID-19 isolate for …