Pfizer/BioNTech have submitted early booster shot data to the Food and Drug Administration.

Phase 1 data found that people given a third shot eight to nine months after their primary doses had a boosted immune response and higher neutralizing antibody levels against the delta variant.

Pfizer/BioNTech plan to continue to study booster shots and submit additional data to the FDA.

It's not clear when or if the FDA and Centers for Disease Control and Prevention might recommend booster doses for all. Only severely immunocompromised people are currently eligible.

-ABC News' Sony Salzman

All health workers in New York state, public and private, must get vaccinated by Sept. 27, Gov. Andrew Cuomo announced Monday.

This includes staff at hospitals and long-term care facilities, including nursing homes, adult care and other congregate care settings.

Seventy-five percent of the state's hospital workers and 68% of nursing home workers are already vaccinated.

-ABC News' Aaron Katersky

As COVID-19 cases surge pediatricians are experiencing a first: sick children facing both respiratory syncytial virus, or RSV, and COVID-19.

"We've not seen this before -- we have two very highly contagious respiratory viruses circulating at the same time, particularly throughout the South around Texas and neighboring states," Dr. Jim Versalovic, pathologist-in-chief at Texas Children's Hospital, told ABC News Live on Monday.

Infants, young children and older adults are most at-risk for RSV, a respiratory virus that's usually more prevalent in the fall and winter. RSV kills 100 to 500 children under 5 each year, according to the Centers for Disease Control and Prevention.

"It's not surprising now to see children being impacted with both viruses, particularly infants and young children who are most susceptible to respiratory syncytial virus," Versalovic said.

He said in "recent weeks we've had 30% or more of our pediatric ICU beds [filled] with RSV infections," including some children also with COVID-19, which "could "mean more severe respiratory illness."

"We do know how to treat these children with RSV and with COVID. And so, for now we're managing that, but it is certainly a new challenge for us," Versalovic said.

The positivity rate has climbed to 25% at Children's Hospital New Orleans, Dr. Mark Kline, the hospital's physician-in-chief, told ABC News on Sunday.

The hospital had 12 pediatric patients on Sunday. Half of them were under 2 years old, Kline said.

Five of the 12 patients in the hospital were in the ICU: an 8-week-old, a 3-month-old, a 13-month-old, a 23-month-old and a 17-year-old, Kline said.

"As we see more children infected and ill with COVID-19, it occurs to me that our children have become the collateral damage of many adults who frame refusal of masks and vaccines as an issue of personal freedom rather than the common-sense public health measures that they are," Kline said.

"Children currently have no way out of this pandemic other than through the advocacy and personal responsibility of their parents and all adults," Kline added. "So far, we are failing them miserably."

-ABC News' Mark Abdelmalek

More than 880,000 doses of the Moderna COVID-19 vaccine donated by the United States arrived in Kenya on Monday morning.

The 880,460 doses were given to the East African nation by the U.S. government via the global vaccine-sharing scheme COVAX, according to a press release from the United Nations International Children's Emergency Fund (UNICEF), which is leading vaccine procurement and delivery efforts on behalf of COVAX. It is the first of two shipments, totaling 1.76 million donate doses.

The donation marks the first time that Kenya has received the Moderna vaccine, widening the portfolio of COVID-19 vaccines available for the country's ongoing rollout of its national immunization campaign. All Kenyans over the age of 18 are now eligible to be vaccinated against COVID-19. Kenya aims to vaccinate 10 million of its 53 million people by the end of the year.

So far, Kenya has reported more than 229,000 confirmed cases of COVID-19, including at least 4,497 deaths, according to the latest data from the Kenyan Ministry of Health.