Southwest CEO Gary Kelly has tested positive for COVID-19 after testifying at a Senate hearing Wednesday alongside other airline executives, a Southwest spokesperson said.

He was not masked during the hearing.

Kelly, who is fully vaccinated and boosted, has mild symptoms, the spokesperson said.

ABC News reached out to the airlines whose executives were next to Kelly at the hearing.

United Airlines CEO Scott Kirby and Delta operations chief John Laughter tested negative Friday.

American Airlines CEO Doug Parker plans to test Friday afternoon, according to the airline. Sara Nelson, international president of the Association of Flight Attendants-CWA, said she will test Friday and in the coming days.

Senate Commerce Committee Chair Maria Cantwell told ABC News that committee members will "follow the protocols" for testing.

-ABC News' Mina Kaji, Allison Pecorin and Sam Sweeney

More than 4,700 COVID-19 patients are in Ohio hospitals, the highest number of all of 2021 -- and hospitalization numbers are quickly approaching an all-time high, Gov. Mike DeWine's office said.

DeWine said he's calling up 1,050 National Guard members to help overwhelmed hospitals beginning on Monday.

The potential timeline for when children under 5 may have an authorized vaccine is now being pushed back.

Data for a two-shot vaccine was initially expected by the end of the year, but now Pfizer/BioNTech say they hope to have data with a third shot in the first half of 2022.

Pfizer/BioNTech said they "will amend the clinical study evaluating the safety, tolerability, and immunogenicity of the Pfizer-BioNTech COVID-19 Vaccine in children 6 months to under 5 years of age. The study will now include evaluating a third dose of 3 µg at least two months after the second dose of the two-dose series to provide high levels of protection in this young age group."

An early look into the study data suggested that the two doses at a smaller volume was not as effective for kids ages 2 to 5 as it was for the 16 to 25 population, so scientists are going to add a third dose and see if the vaccine is as effective. There were no safety issues reported in the early data analysis.

Pfizer/BioNTech added in a statement, “The decision to evaluate a third dose of 3 µg for children 6 months to under 5 years of age reflects the companies’ commitment to carefully select the right dose to maximize the risk-benefit profile. If the three-dose study is successful, Pfizer and BioNTech expect to submit data to regulators to support an Emergency Use Authorization (EUA) for children 6 months to under 5 years of age in the first half of 2022.”

-ABC News' Eric M. Strauss

Americans in their 30s are accounting for the highest case rate of any age group, according to federal data.

The U.S. is now reporting nearly 120,000 new cases each day. The daily case average has surged by nearly 86.3% since late October, according to federal data.

Thirty-three states, as well as Washington, D.C., and New York City, have seen at least a 10% jump in daily cases over the last two weeks.

New Hampshire currently holds the nation's highest case rate, followed by Rhode Island, Maine, Wisconsin, Connecticut and Massachusetts, according to federal data.

-ABC News' Arielle Mitropoulos

A journalist traveling alongside U.S. Secretary of State Antony Blinken on his visit to Southeast Asia has tested positive for COVID-19 in Malaysia, according to U.S. Department of State spokesperson Ned Price.

Meanwhile, Blinken and his senior staff all tested negative for COVID-19 upon arrival in Kuala Lumpur on Tuesday night. The member of the traveling press pool who tested positive had last tested negative in Indonesia's capital, their previous stop, on Tuesday.

"The individual who tested positive will remain in isolation," Price said in a statement Wednesday, "and we will continue to adhere to and go beyond CDC guidance, including with our rigorous testing protocol, for the remaining traveling party."

Blinken has canceled a scheduled trip to Thailand "out of an abundance of caution" and will return home to the United States, according to Price.

"The Secretary expressed his deep regret to the Foreign Minister that he would not be able to visit Bangkok this week," Price said. "He explained that, in order to mitigate the risk of the spread of COVID-19 and to prioritize the health and safety of the U.S. traveling party and those they would otherwise come into contact with, the Secretary would be returning to Washington, D.C. out of an abundance of caution."

"The Secretary extended an invitation for the Foreign Minister to visit Washington, D.C. at the earliest opportunity and noted that he looked forward to traveling to Thailand as soon as possible," Price added. "They affirmed that they would use the upcoming engagements to further deepen the U.S.-Thai alliance."

The U.S. Embassy in Malaysia confirmed that the infected individual "was not involved and has not participated in any of Secretary Blinken's program in Kuala Lumpur."

"The sole member of the traveling party who tested positive is observing all requirements of the Ministry of Health," the embassy said in a statement Wednesday. "We confirm all other members of the party tested negative for COVID-19 upon arrival in Malaysia."

Blinken was in Indonesia on Tuesday, and the U.S. Embassy in Jakarta confirmed that no members of the traveling party tested positive for COVID-19.

All members of the U.S. delegation are required to be vaccinated against COVID-19 and undergo regular testing on trips.

-ABC News' Conor Finnegan