Coronavirus Watch: Vaccinations speed up, but is another surge of infections coming?

More than 3 million coronavirus vaccine doses were reported administered across the nation on back-to-back days for the first time as the pace of vaccinations continues to increase.

Almost one-quarter of the entire U.S. population – and almost one-third of adults – has received at least one dose, according to data from the Centers for Disease Control and Prevention. But Dr. Rochelle Walensky, CDC director, warned Monday that data on new cases and hospitalizations indicates numbers are again rising in the Northeast and Upper Midwest. A nationwide surge could be coming if Americans do not continue wearing masks, socially distancing and adhering to other restrictions, she said.

"The apparent leveling off of cases and hospital admissions, after the consistent decline in early January through the end of February, I consider to be very concerning," she said.

It's Monday, and this is the Coronavirus Watch from the USA TODAY Network. Here's more news you need to know:

• AstraZeneca said Monday that advanced trial data from a U.S. study on its vaccine shows it is 79% effective at preventing symptomatic COVID-19 and 100% effective in stopping severe disease and hospitalization. AstraZeneca says it plans on seeking FDA emergency authorization for use in the U.S.
• New York state will expand COVID-19 vaccine eligibility to everyone age 50 and up starting Tuesday, Gov. Andrew Cuomo said. President Joe Biden has directed states to make all U.S. adults eligible for vaccinations by May.
• Miami Beach's entertainment district will remain in a state of emergency with an 8 p.m. curfew until Tuesday evening. Miami Beach Interim City Manager Raul Aguila said an influx of spring breakers has overwhelmed the city, raising COVID-19 concerns.
• Kristy Kreme is providing a sweet incentive to encourage vaccinations – free doughnuts through the end of 2021. Starting Monday, consumers who show a valid COVID-19 vaccination card at locations nationwide will get a free Original Glazed doughnut. The freebie is valid at all 369 Krispy Kreme shops in 41 states.

Today's numbers: The U.S. has reported more than 2.9 million COVID-19 cases and 542,000 deaths, according to data from Johns Hopkins University. Worldwide, there have been more than 123 million cases and more than 2.7 million deaths. More than 24% of people in the U.S. have received at least one vaccine shot, and 13.3% of people have received both doses, according to the CDC.

See the numbers in your area here, check out where cases are rising here, and see how many vaccines your state has received here.

– John Bacon, USA TODAY rewrite chief, @realjohnbacon