The novel coronavirus pandemic has now killed more than 650,000 people worldwide.
Over 16.3 million people across the globe have been diagnosed with COVID-19, the disease caused by the new respiratory virus, according to data compiled by the Center for Systems Science and Engineering at Johns Hopkins University. The actual numbers are believed to be much higher due to testing shortages, many unreported cases and suspicions that some governments are hiding or downplaying the scope of their nations' outbreaks.
The United States has become the worst-affected country, with more than 4.2 million diagnosed cases and at least 147,791 deaths.
Here is how the news developed on Monday. All times Eastern.
7:40 p.m.: Pfizer chooses lead vaccine candidate for Phase 2/3 global trial
Pfizer and German partner BioNTech are ready to start a combined Phase 2/3 global trial of one of their coronavirus vaccine candidates, the companies announced Monday.
The vaccine, one of four candidates in development, had undergone safety testing in Phase 1. The combined Phase 2/3 trial will enroll up to 30,000 participants between the ages of 18 and 85 at about 120 clinical sites around the world, including in 39 states in the U.S. One of the first sites will be at the University of Rochester in New York state.
Participants will be screened and dosed in the next few days.
Pfizer is seeking regulatory review for its coronavirus vaccine candidate as early as October 2020 and aims to manufacture up to 100 million doses by the end of 2020 and up to 1.3 billion doses by the end of 2021.
Last week, the U.S. government announced a $1.95 billion deal to gain access to at least 100 million doses of a Pfizer vaccine if it proves to be safe and effective.
On Monday, Moderna Therapeutics announced it would become the first U.S. company to enter Phase 3 of a clinical trial for a potential coronavirus vaccine.
6:15 p.m.: Police bust 700-person house party at New Jersey Airbnb
A weekend party at an Airbnb in Ocean County, New Jersey, allegedly drew upwards of 700 people, in violation of the state's executive order on gatherings during the pandemic, police said.
The Jackson Police Department responded to a residence at around 8:30 p.m. on Sunday following the report of a suspicious incident, officials said. According to police, the homeowner rented the house on Airbnb for a "large party."
After discovering over 700 people with more than 100 cars parked in the area, officers started to clear the party and shut down roads into the neighborhood to prevent more people from arriving, officials said. Jackson police officers were able to clear the neighborhood of party attendees and cars by 1 a.m. with the assistance of the several neighboring police departments and New Jersey State Police, officials said.
Both the homeowner and the renters were issued summonses for violating the executive order limiting indoor gatherings to 100 people due to coronavirus concerns, police said.
Airbnb said it has deactivated the listing as the company investigates the incident, and it has removed the two alleged party organizers from the platform.
"We strongly condemn the reported behavior, which represents both a clear violation of Airbnb’s community policies and a particularly serious abuse during this public health crisis," Airbnb said in a statement.
4:20 p.m.: Kentucky to close bars for 2 weeks
As coronavirus cases escalate in Kentucky, Gov. Andy Beshear said bars must close for two weeks, effective Tuesday.
At a news conference Monday, Beshear showed photos of crowded bars from this weekend, where patrons didn't have masks or follow social distancing guidelines.
Indoor restaurant capacity will be limited to 25%, Beshear added.
Beshear also said he is recommending that public and private schools postpone in-person classes until at least the third week of August.
"By waiting ... we believe it gives us a chance to get this thing under better control," the governor said.
Kentucky has over 27,000 COVID-19 cases.
Beshear said he wants to do everything he can to keep Kentucky's current situation from getting worse.
3:30 p.m.: St. Louis announces curfew for bars, new rules for health providers
As coronavirus cases rise in St. Louis County, Missouri, officials are implementing tighter restrictions, as well as new rules for health providers and those waiting for test results.
Beginning Friday, bars must close at 10 p.m. and gatherings will be reduced to under 50 people, officials announced Monday.
Anyone waiting for COVID-19 testing results is asked to self-quarantine, even if asymptomatic, county officials said.
Health providers must report results in a timely manner, the officials said, and the county is asking the director of human services to help find safe places for teachers to quarantine.
3 p.m.: Herman Cain remains in hospital, being treated with oxygen for lungs
Former Republican presidential candidate Herman Cain remains hospitalized and is "being treated with oxygen for his lungs," a spokesperson said Monday, nearly one month after it was announced that Cain was hospitalized with the coronavirus.
"The doctors say his other organs and systems are strong," a spokesperson added.
Cain's hospitalization was announced on July 2.
Cain, a Black Voices for Trump co-chair, attended President Donald Trump's June 20 rally in Tulsa. Cain posted a photo of a group at the rally without masks or social distancing.
2:20 p.m.: 100 federal inmates have died of COVID-19
One-hundred federal inmates have died of COVID-19, according to statistics from the Federal Bureau of Prisons.
FCI Butner in North Carolina has been the hardest hit, with 16 deaths in the facility.
Overall in federal prisons just under 10,000 inmates and 1,000 staff have tested positive for COVID-19, officials said.
1:40 p.m.: Miami Beach mayor writes scathing letter to governor blasting state contact tracing program
Miami Beach Mayor Dan Gelber on Monday wrote a scathing letter to Florida Gov. Ron DeSantis, blasting the state's contact tracing program.
Gelber's letter called the state's contact tracing program in Miami-Dade County "unprepared to meet the challenges of this pandemic" and urged DeSantis "to take immediate action to expand its capacity and improve its competencies."
Gelber said when Miami-Dade County reopened its economy in May, Florida's "contact tracing program fully failed to cabin subsequent disease surges," leading to "unconstrained growth of the virus," according to the letter obtained by ABC News.
Florida is now the state with the second-highest number of cases. California has the highest and New York has the third highest.
"If we don’t have a capable and fully resourced program in place, I don’t see how we can even contemplate opening schools or other aspects of our economy. In fact, if we continue at this level of infection, I don’t know how we don’t return to sheltering in place," Gelber wrote.
He added, "it is evident that they [DOH staff] are understandably wary of providing candid self-assessments of the shortcoming of their contact tracing efforts and staffing to local leaders to whom they don’t report."
12:18 p.m.: Critical care chief at Baltimore hospital dies from COVID-19
Dr. Joseph Costa, the chief of critical care at Baltimore's Mercy Medical Center, died from COVID-19 on Saturday, his family said, according to The Baltimore Sun.
"He dedicated his life and career to caring for the sickest patients," Mercy Medical Center said in a statement. "And when the global pandemic came down upon us, Joe selflessly continued his work on the front lines—deeply committed to serving our patients and our City during this time of great need."
Dr. Costa "was beloved by his patients and their family members—known for his warm and comforting bedside manner as well as his direct and informative communication style," the statement added. "When he counseled our patients and families, he did so with great compassion and empathy. For all the nurses and staff who worked closely with Joe on the Intensive Care Unit, he was like an older brother that all admired and revered."
11:45 a.m.: Gym owners charged for allegedly keeping business open despite court order
Two men who own a Bellmawr, New Jersey, gym were arrested Monday morning after allegedly keeping the gym open despite a judge issuing a contempt order against them on Friday, according to the Camden County Prosecutor's Office.
In between Friday and Monday, "a number of individuals" were seen using Atilis Gym, prosecutors said.
"Police said both owners refused to leave the gym when asked, leading to the charges," prosecutors said.
The men were each charged with obstruction, violation of a disaster control act and fourth-degree contempt, prosecutors said. They were released early Monday.
11:10 a.m.: Florida's daily cases below 9,000 for 1st time in at least 2 weeks
Hard-hit Florida reported 8,892 new coronavirus cases Monday morning -- the first time its daily case count was below 9,000 in at least two weeks, according to data from the state's Department of Health.
Throughout Florida, just 18.82% of ICU beds remained available Monday morning, according to the state's Agency for Healthcare Administration.
Monroe County and Okeechobee County had no ICU beds available, the agency said.
ICU availability will fluctuate throughout the day as hospitals and medical centers provide updates.
10:20 a.m.: Cases have roughly doubled worldwide in last 6 weeks
Coronavirus cases have roughly doubled worldwide in the last six weeks, World Health Organization (WHO) Director-General Dr. Tedros Adhanom Ghebreyesus said Monday.
This is the sixth time a global health emergency has been declared and COVID-19 "is easily the most severe," Tedros said.
In the countries following hand washing, social distancing and mask guidance, cases are going down, Tedros said. In the countries not following those rules, cases are rising, he said.
Tedros said Cambodia, New Zealand, Rwanda, Thailand and Vietnam prevented large-scale outbreaks, while Canada, China, Germany and South Korea brought large outbreaks under control.
9:37 a.m.: Miami Marlins' home opener canceled due to COVID-19 breakout
The Miami Marlins' home opener -- set for Monday night against the Baltimore Orioles -- has been canceled due to a COVID-19 breakout, ESPN reported.
At least 14 people, including players and coaches, have tested positive in recent days, sources told ESPN.
The Marlins remain in Philadelphia where they played the Philadelphia Phillies Sunday night. The Phillies were set to host the New York Yankees Monday night but the game has since been postponed.
The MLB said it is conducting more testing.
"The members of the Marlins’ traveling party are self-quarantining in place while awaiting the outcome of those results," the MLB said.
8:20 a.m.: No live family tributes on Sept. 11 anniversary
This year on Sept. 11, the ceremony marking the anniversary of the terror attacks will not include the annual in-person recitation of names by victims' relatives.
The National September 11 Memorial and Museum informed the families in a letter that, because of the pandemic, the reading of names during the commemoration would be recorded.
Families are still welcome on the plaza in lower Manhattan for an event with social distancing and masks.
The ceremony will still mark six moments of silence for when the planes struck the World Trade Center, when the towers fell, when the Pentagon was attacked and when UA93 crashed in a Pennsylvania field.
What to know about coronavirus:
3:51 a.m.: Italy cracks down on mask use
Several businesses in Naples have been fined 1,000 euros after they were deemed responsible "during a commercial transaction" for customers and clients who did not wear a mask in their establishment.
Besides fines, the government can also force businesses to close for a period between five to 30 days if they are found to be not in compliance. France will also introduce fines of 135 euros for people who do not wear a mask in public spaces indoors.
12:56 a.m.: NFL players who attend 'high-risk' events and contract coronavirus face team discipline, lack of pay
NFL players who contract the coronavirus through "high-risk" activity away from team facilities can face team discipline and might be at risk of not being paid, according to the league's new protocol.
A memo sent by the NFLPA to agents this weekend, a copy of which was obtained by ESPN, outlines several rules governing player contracts, opt-out provisions and the contractual consequences of a canceled season.
The memo says that the final language of Friday's agreement between the league and the players will appear in a side letter that is still being negotiated and that the information distributed this weekend represents "a summary of major aspects of the COVID amendments." The basics have been dealt with, and the final section of the memo is devoted to the fact that players will be held responsible for the way they circulate in public while the coronavirus remains present.
Players were told weeks ago on a conference call with NFLPA leadership that they could face discipline, including fines, for conduct detrimental to the team if they are found to have contracted COVID-19 through reckless activity away from the facility. This weekend's memo reinforces that and says that such activity could allow a team to challenge the status of a COVID-19 diagnosis as a football injury.
If such a challenge were to succeed, presumably the team could place the player on the non-football injury list, a move that would allow the team the option of not paying him.
The memo also states: "Clubs/NFL can challenge designation as a football related injury if it can prove that the player contracted COVID-19 through engaging in high risk conduct below. (This issue remains open.)"
"Players are going to have to be careful outside the building," Los Angeles Rams tackle Andrew Whitworth said last week on a conference call after disclosing that he and his entire family got the virus after one of them went to lunch with a friend. "All it takes is one exposure, and it can spread like wildfire."
ABC News' Luke Barr, Clark Bentson, Dee Carden, Ben Gittleson, Will Gretsky, Bill Hutchinson, Joshua Hoyos, Aaron Katersky, Victor Oquendo, Christine Theodorou, Teri Whitcraft, Scott Withers and Erin Zimmerman contributed to this report.