People with appointments stand in line to receive the Covid-19 vaccine in East Los Angeles. California has announced an updated vaccine delivery plan after facing mounting criticism over a slow vaccine rollout. Mario Tama/Getty Images
California and other large states are loosening Covid-19 restrictions; however, it’s still not clear how long immunity lasts after being vaccinated and how it will hold up against new SARS-CoV-2 variants.Bing Guan/Bloomberg/Getty Images
People line up outside a free COVID-19 vaccination site on Dec. 3 in Washington, D.C. Many areas are stepping up vaccination and booster shots as more cases of the omicron variant of the coronavirus are detected in the United States. / Samuel Corum