Here are some significant developments:
- More than 4 million people in the United States received a coronavirus vaccine on Saturday — the nation’s highest one-day total since the shots began rolling out in December — amid a rising caseload and increase in hospitalizations.
- While no connection has been established between AstraZeneca’s vaccine and rare but potentially deadly blood clots, new treatment guidelines have been adopted in Europe.
- New Zealand said Tuesday it was launching a quarantine-free travel bubble with Australia later this month. Travelers would still be subject to restrictions, but the new program could help reunite families separated by the pandemic.
- China is offering its citizens an array of incentives, including free food, to ramp up a flagging vaccine drive that aims to inoculate 40 percent of its enormous population by June.
- Montana Gov. Greg Gianforte (R) has tested positive for the coronavirus and will quarantine for 10 days, his office said Monday. His wife, Susan Gianforte, has exhibited no symptoms and is awaiting her test results, the office said.
- Mass inoculation may shield the unvaccinated, in addition to the immunized, a new study by Israeli researchers suggests.