Jesse Jackson, wife hospitalized with COVID-19

U.S. Surgeon General Vivek Murthy announced at Wednesday's White House briefing, "Having reviewed the most current data, it is now our clinical judgment that the time to lay out a plan for COVID-19 boosters is now."

Murthy said protection against mild disease has decreased, likely a combination of waning vaccine protection over time and the strength of the delta variant, and that the administration is "concerned" that protection could continue to erode.

"Even though this new data affirms that vaccine protection remains high against the worst outcomes of COVID, we are concerned that this pattern of decline we're seeing will continue in the months ahead, which could lead to reduced protection against severe disease, hospitalization and death," Murthy said.

"That is why, today, we are announcing our plan to stay ahead of this virus by being prepared to offer COVID-19 booster shots to fully vaccinated adults 18 years and older," Murthy said. "They would be eligible for their booster shot eight months after receiving their second dose of the Pfizer or Modern mRNA vaccines."

The boosters are set to begin Sept. 20, but Murthy emphasized that this is pending FDA authorization and also reiterated that does not yet apply to J&J recipients.

-ABC News' Cheyenne Haslet

New York City botched its COVID-19 response, according to an investigation conducted by Scott Stringer, the city's comptroller, who released findings from his inquiry Wednesday.

According to Stringer, key emergency response agencies, including the health department and the NYPD, were intentionally excluded from communications and decision-making "when time was of the essence."

The comptroller also described persistent confusion about the chain of command between agencies and a significantly delayed response to the pandemic.

Officials waited until late February to even begin planning for a worst-case scenario, despite knowing about the impending crisis in January. Stringer called on the mayor, as well as the future mayor, to conduct a thorough review of the city's emergency planning process.

"We cannot erase the mistakes of the past," he said. "But we can make sure we are prepared for future emergencies."

-ABC News' Aaron Katersky

A new CDC analysis found that Pfizer and Moderna vaccine efficacy dropped "significantly" among nursing home residents from March to July, as the delta variant became the predominant strain in the United States.

Researchers analyzed weekly reports from thousands of nursing home facilities in the U.S. and found that mRNA vaccines were roughly 75% effective against preventing any infection in late winter/early spring of 2021, early in the mass vaccination rollout and prior to the emergence of the delta variant. By summer of this year, effectiveness against any infection had dropped to 53%.

Crucially, this doesn't mean vaccines aren't working for nursing home residents, but the significant drop in effectiveness from March to July may support the use of booster doses for them, according to the CDC report.

A second analysis found that the mRNA vaccines are holding up well against hospitalizations for COVID-19. The research, which was conducted across 21 U.S. hospitals, found that the Pfizer and Moderna vaccines remained between 84% and 86% effective against potential hospitalizations from March to July of this year. A third analysis, conducted in New York State, found that all three authorized vaccines remained more than 90% effective at preventing hospitalization from early May to late June.

-ABC News' Sony Salzman, Eric Strauss

The U.S. is prepared to offer booster shots for all Americans beginning the week of Sept. 20, top health officials announced Wednesday. Starting eight months after a person's second dose, they are eligible for a booster.

"At that time, the individuals who were fully vaccinated earliest in the vaccination rollout, including many health care providers, nursing home residents, and other seniors, will likely be eligible," Rochelle Walensky, director of the CDC; Janet Woodcock, acting FDA commissioner; Dr. Vivek Murthy, surgeon general; Francis Collins, director of the NIH; and Anthony Fauci, director of the NIAID, said in a joint statement.

The data behind the decision is expected to be released at 11 a.m. EST during the White House COVID briefing, but public health officials said it's clear that vaccines are waning over time and "we are starting to see evidence of reduced protection against mild and moderate disease."

With regard to the Johnson & Johnson vaccine, officials stressed that more data will be released in the next few weeks. "We will keep the public informed with a timely plan for J&J booster shots," they said.

-ABC News' Cheyenne Haslett