White House officials on Sunday announced that vaccine distribution sites will receive their first doses of Johnson & Johnson's (J&J's) newly authorized Covid-19 vaccine as early as Tuesday morning, and they're urging Americans to get vaccinated as soon as they can, as the country's recent decline in new coronavirus cases has plateaued.

Our 8 biggest questions about Johnson & Johnson’s Covid-19 vaccine, answered

FDA authorizes 3rd Covid-19 vaccine for use in US

FDA on Saturday issued an emergency use authorization (EUA) for J&J's single-dose Covid-19 vaccine based on data from J&J's 45,000-person, international clinical trial. According to the trial's data, the vaccine was 66.9% effective at preventing moderate to severe Covid-19 among patients who had been vaccinated for at least two weeks. The data also showed there were no Covid-19 hospitalizations or fatalities among patients who had been vaccinated for at least 28 days.

In addition, there were no reports of severe allergic reactions, such as anaphylaxis, among those who received the vaccine as part of the trial, according to the data. Further, reported side effects in the trial appeared to be milder than those linked to the two-dose Covid-19 vaccines produced by Pfizer/BioNTech and Moderna, which FDA authorized for use in the United States last year.

Experts also have noted that J&J's vaccine has certain logistical advantages over Pfizer/BioNTech's and Moderna's vaccines. Specifically, J&J's vaccine can be stored at normal refrigeration temperatures for at least three months, and it only requires one dose.

Following FDA's EUA, the Advisory Committee on Immunization Practices, which is a panel of outside experts that advises CDC on vaccines, on Sunday voted 12-0 (with one abstention) to recommend the distribution of the J&J's vaccine to all adults in the United States. CDC Director Rochelle Walensky signed off on the committee's recommendation, allowing distributors to begin shipping the vaccine.

Later on Sunday, White House officials announced that vaccine distribution centers should begin receiving a total of 3.9 million doses of J&J's Covid-19 vaccine as early as Tuesday. Officials said distributors will ship a total of 20 million doses of the vaccine throughout March, with about 16 million of those doses being shipped during the second half of the month. According to STAT News, the first shipments of J&J's vaccine in March will account for the entirety of J&J's current vaccine inventory.

"We do not expect any additional deliveries next week and we expect deliveries to be uneven during the weeks of March," a senior Biden administration official said. The official added, "We're getting doses out the door as soon as they're available to ensure vaccines get into the arms as quickly as possible."

The federal government plans to distribute the vaccine doses it purchased from J&J in proportion to states' populations, which is the same way the government allocated Pfizer/BioNTech's and Moderna's vaccine. In total, the federal government has purchased 100 million doses of J&J's vaccine, but supplies are expected to be limited until at least April. According to the New York Times, J&J is currently trying to ramp up production of the vaccine.

Experts say Americans should feel 'confident' about J&J's vaccine—and get vaccinated as soon as possible

Officials said the United States' three authorized Covid-19 vaccines will be available in every community, though every vaccine may not be available at every vaccine site. As a result, officials said Americans likely won't be able to choose which vaccine they receive at this point in the country's vaccine rollout.

However, officials said people shouldn't wait for a particular company's vaccine to become available to get vaccinated.

"Having different types of vaccines available for use, especially ones with different dosing recommendations and storage and handling requirements, can offer more options and flexibility for the public, jurisdictions, and vaccine providers," Walensky said. "Getting vaccinated with the first vaccine available to you will help protect all of us from Covid-19."

During an interview with NBC's "Meet the Press" on Sunday, Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases and chief medical adviser for the White House's Covid-19 response, said, "All three of [America's Covid-19 vaccines] are really quite good, and people should take the one that's most available to them."

Separately, Scott Gottlieb, who served as FDA commissioner under former President Donald Trump, during an appearance on CBS' "Face the Nation" said Americans should be "confident" about taking J&J's Covid-19 vaccine.

"I think this is a good vaccine. The vaccine was very effective at preventing severe disease, 85% effective at preventing severe and critical disease," Gottlieb said. "Also, interestingly, if you look at the clinical data, it was 74% effective at preventing asymptomatic infection, which is a suggestion that it is preventing transmission as well."

Officials and public health experts say it's particularly important for Americans to get vaccinated as soon as they're able because data indicates declines in the country's rate of newly reported coronavirus infections are slowing—and the rate of new cases may be starting to tick up once again.

"The most recent seven-day average of cases, approximately 66,350, is higher than the average I shared with you" on Feb. 24, Walensky said Friday. "In fact, cases have been increasing for the past three days compared to the prior week."

Where America's coronavirus epidemic stands

While the United States in recent weeks had seen progress in its rates of newly reported coronavirus cases, hospitalizations, and deaths, the reported rates of each of those metrics have remained high—with the country reporting more daily coronavirus cases than it had in April and July—and the declines appear to be halting.

As a result, public health officials and experts have explained that America is currently at a crossroads in the epidemic, with the potential to see continued progress or for that progress to reverse if Americans stop following public health measures intended to curb the coronavirus's spread.

"Things are tenuous," Walensky said. "Now is not the time to relax restrictions" aimed at slowing transmission.

Separately, Fauci during an interview with "Face the Nation" said, "That's exactly the thing that happened during previous surges. As it peaked and started to come down, people withdrew some of the intensity of the public health measures and it kind of stabilized at a very high level. That's very dangerous."

According to data compiled by the New York Times, U.S. officials on Sunday reported about 50,925 new cases of the novel coronavirus. As of Monday morning, officials had reported about 28.6 million cases since the United States' epidemic began.

According to the Times, the United States' average daily number of newly reported coronavirus cases over the past week was 67,868—down by 26% when compared with the average from two weeks ago.

However, the Times' data showed that, as of Monday morning, the rates of newly reported coronavirus cases were "staying high" in Washington, D.C., and 10 states that have reported a daily average of at least 15 newly reported cases per 100,000 people over the past week. Those states are Colorado, Connecticut, Delaware, Georgia, Idaho, Massachusetts, New Jersey, New York, South Dakota, and Vermont.

In addition, the rate of newly reported coronavirus cases was "going up" as of Monday morning in the U.S. Virgin Islands, which has had comparatively lower case rates, the Times reports.

According to the data, rates of newly reported coronavirus cases were "staying low" or declining from previously higher rates in Guam, Puerto Rico, and the remaining U.S. states and territories.

Meanwhile, data from The Atlantic's COVID Tracking Project shows there were 47,352 Americans with Covid-19 hospitalized for treatment on Sunday, including 9,802 who were receiving care in an ICU and 3,245 who were on a ventilator.

Further, data from the Times shows that U.S. officials reported about 1,129 new deaths linked to the coronavirus on Sunday. As of Monday morning, officials had reported about 512,979 U.S. deaths linked to the virus since the country's epidemic began.

(Owens, "Vitals," Axios, 3/1; Neergaard/Perrone, Associated Press, 2/28; Groppe, USA Today, 2/28; Cohrs, STAT News, 2/28; LaFraniere, New York Times, 2/28; Newburger, CNBC, 2/28; Hayes, CBS News, 2/28; Facher, STAT News, 2/26; Quinn, CBS News, 2/28; Stolberg, New York Times, 2/26; New York Times, 3/1; "COVID Tracking Project," The Atlantic, accessed 3/1).