Dr. Jerome Adams, the U.S. surgeon general under former President Donald Trump, slammed the U.S. Centers for Disease Control and Prevention over its change on isolation times for infected individuals.

In a Twitter thread, Adams criticized the agency's decision to omit the recommendation for COVID-19-positive individuals to take a COVID-19 test, prior to ending isolation.

The CDC reduced the isolation period from 10 days to five for asymptotic patients.

"Regardless of what CDC says, you really should try to obtain an antigen test (I know- easier said than done) and confirm it’s negative prior to leaving isolation and quarantine. There’s not a scientist or doctor I’ve met yet who wouldn’t do this for themselves/ their family," Adams tweeted.

The former surgeon general added, "This isn’t about the best science – it’s a compromise to keep the economy open in the face of inadequate tests."

-ABC News' Arielle Mitropoulos

The NFL and NFL Players Union agreed to new guidelines for when a player who is infected with COVID-19 can return to the field, according to ESPN.

Players who test positive can isolate for five days, in accordance with the new recommendations from the U.S. Centers for Disease Control and Prevention.

The agreement includes both vaccinated and unvaccinated players and is contingent on the players being asymptomatic, or at least demonstrating that their symptoms are resolving, after the five-day period, ESPN reported.

Under the current rules, unvaccinated players are required to isolate for 10 days when they test positive. Vaccinated players can return to the field as soon as they test negative.

The U.S. Centers for Disease Control and Prevention is investigating 86 cruise ships operating or planning to operate in U.S. waters that have reported COVID-19 cases.

In order to meet the threshold for a CDC investigation, a ship must report COVID-19 cases in more than 0.10% of passengers or have a single crew member test positive in the previous seven days.

The CDC started by investigating 38 ships, and has now investigated 48 additional vessels, which remain "under observation."

None of the ships have been designated as "red," which means they haven't reached the level of COVID-19 transmission needed to overwhelm the medical resources on board.

-ABC News' Mina Kaji

The U.S. Food and Drug Administration revealed new data on the efficacy of antigen tests for detecting the omicron COVID-19 variant.

The data so far suggests the tests do detect the variant, but they may have reduced sensitivity, the agency said.

The FDA and National Institutes of Health will continue to review the antigen tests' performance on the variant.

The U.S. recorded more than 486,000 new COVID-19 cases in a day, marking the third straight day of record numbers, according to data released by the U.S. Centers for Disease Control and Prevention.

The new data comes as states are going through their huge backlogs of tests taken during the Christmas weekend.

In the last week, the U.S. has reported more than 2.2 million new cases, which averages out to about 220 Americans testing positive for COVID-19 every minute.

The CDC will not be providing new data updates until Jan. 3, due to the New Year's holiday.

-ABC News' Arielle Mitropoulos