COVID-19 updates: US has 1st day since November with fewer than 100K new cases

A COVID-19 vaccine developed by England's University of Oxford and British-Swedish pharmaceutical giant AstraZeneca not only protects people from serious disease and death but also may have a substantial effect on transmission of the virus, according to a new study that has not been peer-reviewed.

In a preprint published Tuesday, which is currently under peer review at the medical journal The Lancet, University of Oxford researchers said an analysis of further data from ongoing clinical trials of the two-dose vaccine shows a 67% reduction in positive swabs among those who received a single dose.

It's the first study to document evidence that any COVID-19 vaccine can reduce transmission of the virus.

Researchers said the analysis also reveals the vaccine efficacy is higher at longer prime-boost intervals and that a single dose of the vaccine is 76% effective from 22- to up to 90-days post vaccination, according to the manuscript.

Olympics organizers unveiled on Wednesday the first of a series of "playbooks," step-by-step guides for key stakeholders to a safe and successful Games in Tokyo this summer amid the coronavirus pandemic.

"We are very confident for a number of reasons," Christophe Dubi, Olympic Games executive director of the International Olympic Committee (IOC), said during a virtual press conference. "Tokyo is the best prepared city we have ever seen."

The playbooks explain what to do before leaving home, when entering Japan, during the Games and when leaving the country. The outlined protocols include physical distancing and good hygiene measures, regular testing and temperature checks, as well as rules of conduct until departing Japan.

"Safety would be the utmost priority," Hidemasa Nakamura, Games delivery officer of the Tokyo 2020 organizing committee, told reporters. "The virus will not completely disappear, wherever you are."

"Of course, we have no telling of what the situation will be in the summer," he added.

The playbook released Wednesday, which is for members of international federations and technical officials, states that individuals must take a COVID-19 test approved by the Japanese government within 72 hours of the departure time of their flight to the country, be prepared to take another test at the airport in Japan, expect regular testing during the Games depending on the nature of their role, be ready to have their temperature checked every time they enter an Olympic venue and be prepared to take a final COVID-19 test before departing Japan. They will not need to self-quarantine upon arrival in Japan, nor will they be required to get vaccinated against COVID-19 in order to participate in the Games.

Additional playbooks for athletes, members of the press and others will be published in the coming weeks ahead of the opening of the already delayed Tokyo Olympics on July 23. Updated editions may also be released as the COVID-19 situation evolves, according to organizers.

A decision on whether to limit spectators will be made by spring. Spectators would also be expected to follow a number of rules, organizers said.

ABC News' Anthony Trotter contributed to this report.

The U.S. Centers for Disease Control and Prevention now projects that the country will have recorded up to 534,000 COVID-19 deaths by the end of February.

The CDC on Wednesday published its latest national ensemble forecast, which predicts that the country's COVID-19 death rate will likely decrease over the next four weeks, with 11,300 to 22,600 new fatalities from the disease likely reported nationwide in the week ending Feb. 27. A total of 479,000 to 514,000 COVID-19 deaths are projected to be reported nationwide by this date.

Last week’s national ensemble forecast predicted there would be a total of 479,000 to 514,000 COVID-19 deaths reported nationwide by Feb. 20.

Dr. Anthony Fauci, chief medical adviser on COVID-19 to U.S. President Joe Biden, said people should "absolutely not" host or attend any Super Bowl parties this weekend.

"Watch the Super Bowl on TV, enjoy it, have a party in your house with your family with the people who are there," Fauci told ABC News chief anchor George Stephanopoulos in an interview Wednesday on "Good Morning America."

"You don't want parties with people that you haven't had that much contact with, you just don't know if they're infected," he added. "So as difficult as that is, at least this time around, just lay low and cool it."

Fauci, who is also the director of the National Institute of Allergy and Infectious Diseases, noted that the country is still seeing a "considerable number of cases" each day and there's cause for concern over the new, more contagious variants of the novel coronavirus that were recently detected on U.S. soil.

When asked whether he thinks the Super Bowl could become a superspreader event, Fauci said he hopes not.

"I believe that they are trying to keep people separated enough in the stands wearing masks so they don't have that proximity," he added. "If you're outdoors and you're several feet apart -- 6, 7, 8, 10 feet -- you could be OK, as long as people abide by that and don't slip."