An Aug. 7 wedding and reception in Maine's Millinocket region has been connected to 176 coronavirus cases, according to the state.

Seven coronavirus-related deaths have been linked to the wedding, according to Maine's Center for Disease Control and Prevention. None of those seven people attended the wedding, Maine's CDC said.

ABC News' Rachel Katz contributed to this report.

At the height of COVID-19 pandemic, 1.6 billion students were out of school in 192 countries.

Today, 872 million students -- or half the world's student population in 51 countries -- are still unable to head back to their classrooms, UNICEF executive director Henrietta Fore said Tuesday.

At least 24 million children are projected to drop out of school due to COVID-19, Fore said at a joint press conference with the World Health Organization and United Nations Educational, Scientific and Cultural Organization.

"The sheer number of children whose education was completely disrupted for months on end is nothing short of a global education emergency," Fore said.

WHO emergencies chief Dr. Mike Ryan added, "we have to reduce transmission at community level in order to lower the risk to those older and vulnerable people and to maintain an environment in which our children can continue to attend school."

Ryan said the only way to do that is the adults separate themselves enough to drive transmission downwards.

"What is more important -- our children back at school? Or the nightclubs and the bars open?" Ryan said. "These are the trade-offs."

ABC News' Christine Theodorou contributed to this report.

Francis Collins, director of the National Institutes of Health, told ABC News, "I would expect that if we have a vaccine that's approved by December, by the spring, most Americans will have a chance to access it."

"Certainly by the middle of 2021, we ought to be in a pretty good place," he said.

But Collins stressed, "I'm saying all this with the assumption that one of these vaccines is going to work. We don't know that yet, and until we get to that point, science is not predictable."

Collins said a friend asked him if her daughter should reschedule her May 2021 wedding.

"I didn't quite know what to say," Collins said. "I kind of said, 'Well, you might not reschedule it yet, but you might think about having some flexibility there in case we're still at the tail end of a time where people really shouldn't be gathering in large numbers."

ABC News' Bob Woodruff and Victor Odonez contributed to this report.

The organization that represents the publicly funded hospitals of England warned Tuesday that COVID-19 testing shortages across the country are jeopardizing efforts to restore medical services and prepare for a potential surge in cases over the winter.

The National Health Service (NHS) in England is facing an increase in staff absences due to employees and their family members being unable to access a COVID-19 test. Without a test for either them or their loved ones, NHS staff are having to self-isolate after possible exposure to the virus, taking them away from the front line of the pandemic where they are desperately needed, according to a press release from NHS Providers.

NHS Providers CEO Chris Hopson said that hospital leaders in the British cities of Bristol, London and Leeds all raised concerns over the weekend about the lack of testing. He said hospitals "are working in the dark -- they don’t know why these shortages are occurring, how long they are likely to last, how geographically widespread they are likely to be and what priority will be given to healthcare workers and their families in accessing scarce tests."

"They need to know all this information so that they can plan accordingly," he said in a statement Tuesday. "We need to prioritize tests for healthcare workers and their families and patients coming in for treatment, many of whom have already waited longer than normal."

U.K. Home Secretary Priti Patel told BBC that delays in testing for the public are "unacceptable."