Protests against mandated COVID-19 vaccines pop up across US

A real-world study of South African health care workers found that the single-shot Johnson & Johnson vaccine was highly effective against the delta and beta variants, according to the South African Medical Research Council, which presented the results Friday.

The vaccine was between 91% and 96% effective against death, according the study, which included more than 477,000 health care workers. J&J showed stronger protection against the delta variant, now dominant in the United States and South Africa, than it showed against the beta variant.

"The data reported today by South African investigators show that a single shot can protect against death due to COVID-19 in the most challenging epidemiologic setting: A massive delta surge in Africa," said Dr. Dan Barouch, director of the Center for Virology and Vaccine Research at Beth Israel Deaconess Medical Center, who helped invent the J&J shot but was not directly involved in the South Africa study.

While the results have not yet been published in a peer-reviewed journal, they may serve as a reassuring data point as the delta variant sweeps the U.S.

Glenda Gray, president and CEO of the South African Medical Research Council, who led the study, said at the Friday press conference that the J&J vaccine showed good durability, an indication that there's no need for booster shots just yet.

-ABC News' Sony Salzman.

Thirteen theaters in Washington, D.C., have joined forces to require audiences to supply proof of vaccination in order to attend live performances at indoor venues.

In addition to the vaccination requirement, masks will be required inside the theaters. Medical and religious exemptions to the rule will be accepted, but those patrons will have to show proof of a recent negative COVID-19 test in order to gain entry. For children younger than 12, patrons should contact the theater directly for more information about individual policy.

More theaters are expected to join the cohort in comings weeks, according to Theatre Washington, an alliance of theater organizations and supporters.

A labor analysis by the Texas Workforce Commission found that there are 23,000 openings for registered nurses in Texas and no one to fill them, the Texas Tribune reported Thursday.

The key factor: burnout. Nurses are leaving the profession due to stress from working under COVID-19 conditions for 19 months. And with the delta variant surging across the country, particularly in places like Texas, with lower-than-average vaccination rates, there's no end in sight for the state's health care workers.

New cases, hospitalizations and deaths are all on the rise, according to state data.

All U.S.-based United employees will be required to get vaccinated for COVID-19 by September and must upload their vaccination card to the company website, the airline announced Friday. The move is the strongest vaccination requirement a U.S. airline has taken so far.

"For those employees who are already vaccinated -- and for those employees who get vaccinated and upload their records to Flying Together before September 20th -- we’ll offer an additional day of pay," Scott Kirby and Brett Hart, the CEO and president of United, wrote in a memo to employees.

Employees will have until five weeks after Sept. 20 or five weeks after the Food and Drug Administration fully authorizes a COVID-19 vaccine to upload their cards. All three vaccines in the U.S. are currently being used under emergency use authorization.

-ABC News' Mina Kaji