The year dawned in a blaze of hope that new, effective Covid-19 vaccines -- free and available to all -- would deliver the country from the worst public health emergency in 100 years, in which 350,000 Americans had already died. The promise of a new President, Joe Biden, to shut down the virus rang in the nation's ears after his predecessor had lied about Covid-19's severity, botched the government response and prized his political goals over its health.