The microscopic organisms living in our intestines may influence the severity of Covid-19 and the body’s immune response to it, and could account for lingering symptoms, researchers reported.

Los Angeles health officials told first responders to stop bringing adult patients who cannot be resuscitated to hospitals, citing a shortage of beds and staff as the latest Covid-19 surge threatened to overwhelm healthcare systems in America’s second-largest city.

More than two-thirds of the 15 million coronavirus vaccines shipped within the United States have gone unused, U.S. health officials said on Jan. 4, as the governors of New York and Florida vowed to penalize hospitals that fail to dispense shots quickly.

After collecting billions of dollars in U.S. coronavirus aid, many of the nation’s wealthiest nonprofit hospitals are tapping into disaster relief funds that critics say they do not need.

Millions of Covid-19 vaccines were sitting unused in U.S. hospitals and elsewhere a week into the massive inoculation campaign, putting the government’s target for 20 million vaccinations during December in doubt.

Global coronavirus infections surpassed the 75 million mark on Dec. 19, according to a Reuters tally, as several nations around the world begin vaccinating against the virus.

The number of coronavirus deaths in the United States crossed 300,000 on Dec. 14, according to a Reuters tally, as the hardest hit nation rolled out its first vaccine inoculations on the same day.

The first shipments of Covid-19 vaccine left on trucks and planes early on Dec. 13, kicking off a historic effort to stop a surging pandemic that is claiming more than 2,400 lives a day in the United States.

Five key genes are linked with the most severe form of Covid-19, scientists said, in research that also pointed to several existing drugs that could be repurposed to treat people who risk getting critically ill with the pandemic disease.

A 90-year-old grandmother became the world’s first person to receive a fully tested Covid-19 shot on Dec. 8, as Britain began mass-vaccinating its people in a global drive that poses one of the biggest logistical challenges in peacetime history.