Pandemic-induced drop is biggest in over 75 years; annual population growth has dropped to lowest level in US history

As 4,470 die of coronavirus, authorities set January 26 as date to expand existing measure that previously only targeted UK; other countries also tighten restrictions

15% increase is largest single-year percentage leap since 1918, when tens of thousands of US soldiers died in World War I and hundreds of thousands died in flu pandemic

Rochelle Walensky is head of infectious diseases at Massachusetts General Hospital; US president-elect to nominate California attorney general Xavier Becerra as secretary of health

US president says director of Centers for Disease Control and Prevention is 'confused' for projecting spring 2021 as time when coronavirus will be available for all