US President Donald Trump closes his eyes before signing an executive order calling for more research and flexibility on vaccines, in the Oval Office of the White House in Washington, DC, on August 10, 2026. (Photo by Jim WATSON / AFP via Getty Images)

WASHINGTON, DC - AUGUST 10: White House Deputy Chief of Staff and Homeland Security Advisor Stephen Miller attends an event before U.S. President Donald Trump signs an executive order calling for childhood vaccine shots to be spaced out into separate visits during an event in the Oval Office of the White House on August 10, 2026 in Washington, DC. During his second term, Trump has urged Health and Human Services Secretary Robert F. Kennedy Jr. to investigate further research on vaccines. (Photo by Anna Moneymaker/Getty Images)

WASHINGTON, DC - AUGUST 10: U.S. President Donald Trump speaks before signing an executive order calling for childhood vaccine shots to be spaced out into separate visits during an event in the Oval Office of the White House on August 10, 2026 in Washington, DC. During his second term, Trump has urged Health and Human Services Secretary Robert F. Kennedy Jr. to investigate further research on vaccines. (Photo by Anna Moneymaker/Getty Images)

WASHINGTON, DC - AUGUST 10: U.S. President Donald Trump (R), accompanied by National Institutes of Health Director Jay Bhattacharya (L), and Jayme Leagh Franklin (2nd-L), spesks before signing an executive order calling for childhood vaccine shots to be spaced out into separate visits during an event in the Oval Office of the White House on August 10, 2026 in Washington, DC. During his second term, Trump has urged Health and Human Services Secretary Robert F. Kennedy Jr. to investigate further research on vaccines. (Photo by Anna Moneymaker/Getty Images)

WASHINGTON, DC - AUGUST 10: Health and Human Services Secretary Robert F. Kennedy Jr. joins U.S. President Donald Trump before he signs an executive order calling for childhood vaccine shots to be spaced out into separate visits during an event in the Oval Office of the White House on August 10, 2026 in Washington, DC. During his second term, Trump has urged Health and Human Services Secretary Robert F. Kennedy Jr. to investigate further research on vaccines. (Photo by Anna Moneymaker/Getty Images)

WASHINGTON, DC - AUGUST 10: Health and Human Services Secretary Robert F. Kennedy Jr. joins U.S. President Donald Trump before he signs an executive order calling for childhood vaccine shots to be spaced out into separate visits during an event in the Oval Office of the White House on August 10, 2026 in Washington, DC. During his second term, Trump has urged Health and Human Services Secretary Robert F. Kennedy Jr. to investigate further research on vaccines. (Photo by Anna Moneymaker/Getty Images)

WASHINGTON, DC - AUGUST 10: U.S. President Donald Trump speaks before signing an executive order calling for childhood vaccine shots to be spaced out into separate visits during an event in the Oval Office of the White House on August 10, 2026 in Washington, DC. During his second term, Trump has urged Health and Human Services Secretary Robert F. Kennedy Jr. to investigate further research on vaccines. (Photo by Anna Moneymaker/Getty Images)

WASHINGTON, DC - AUGUST 10: U.S. President Donald Trump speaks before signing an executive order calling for childhood vaccine shots to be spaced out into separate visits during an event in the Oval Office of the White House on August 10, 2026 in Washington, DC. During his second term, Trump has urged Health and Human Services Secretary Robert F. Kennedy Jr. to investigate further research on vaccines. (Photo by Anna Moneymaker/Getty Images)