by Huw GRIFFITH LOS ANGELES, United States (AFP) — All teachers in California will have to be vaccinated against Covid-19 or submit to weekly virus tests, the state’s governor announced Wednesday, as authorities grapple with exploding infection rates. The number of people testing positive for the disease has surged across the United States in recent weeks, with the highly infectious Delta variant blamed for the bulk of new cases. That has worried parents and educators […]