The head of the Centers for Disease Control and Prevention (CDC) overruled the agency's advisory panel Friday by approving the distribution of the Pfizer (PFE  )-BioNTech (BNTX  ) COVID-19 vaccine booster shots to frontline workers in addition to older Americans.

CDC Director Dr. Rochelle Walensky had agreed with several recommendations from the CDC's Advisory Committee on Immunization Practices, including distributing booster shots to older Americans and adults with underlying medical conditions at least six months after their initial two dose regimen. However, Walensky disagreed with the panel's decision on boosters for workers in high-risk jobs, and sided with the Food and Drug Administration's (FDA) authorization of the booster shots earlier this week.

"As CDC Director, it is my job to recognize where our actions can have the greatest impact," Walensky said in a statement. "At CDC, we are tasked with analyzing complex, often imperfect data to make concrete recommendations that optimize health. In a pandemic, even with uncertainty, we must take actions that we anticipate will fo the greatest good."

"I believe we can best serve the nation's public health needs by providing booster doses for the elderly, those in long-term care facilities, people with underlying medical conditions, and for adults at high risk of disease from occupational and institutional exposures to COVID-19," Walensky added.

Under the ruling, about 60 million of the roughly 100 million Americans who received the Pfizer-BioNTech vaccine are now eligible for a third dose.

Here's what the CDC recommends:

  • people 65 years and older and residents in long-term care settings should receive a booster shot of Pfizer-BioNTech's COVID-19 vaccine at least 6 months after their Pfizer-BioNTech primary series,
  • people aged 50-64 years with underlying medical conditions should receive a booster shot of Pfizer-BioNTech's COVID-19 vaccine at least 6 months after their Pfizer-BioNTech primary series,
  • people aged 18-49 years with underlying medical conditions may receive a booster shot of Pfizer-BioNTech's COVID-19 vaccine at least 6 months after their Pfizer-BioNTech primary series, based on their individual benefits and risks, and
  • people aged 18-64 years who are at increased risk for COVID-19 exposure and transmission because of occupational or institutional setting may receive a booster shot of Pfizer-BioNTech's COVID-19 vaccine at least 6 months after their Pfizer-BioNTech primary series, based on their individual benefits and risks.
Walensky said that both the FDA and CDC with work "with the same sense of urgency" on recommendations for Moderna (MRNA  ) and Johnson & Johnson (JNJ  ) booster doses as soon as more data is available to the agencies.