The Food and Drug Administration approved extra shots of Pfizer formula late Wednesday for wide range of Americans, including those over 65, people at high risk for severe illness, health care workers, and anyone else who is in danger of getting infected while on the job.

This was just the beginning. The final U.S. policy regarding who is eligible for an extra shot is set by the Centers for Disease Control and Prevention. The CDC advisers will vote on Thursday to decide how many of the approximately 26 million Americans who received their last Pfizer shot at minimum six months ago should continue to receive that third dose.

The nation’s new vaccination strategy would be a significant step forward with the widespread distribution of boosters. Over strong objections by the World Health Organization, Israel and Britain are already rolling out a third dose of boosters.

According to Dr. Rochelle Walensky, Director of CDC, the priority is still to vaccinate the unvaccinated.

She admitted that data on boosters was not perfect. “But they collectively form a picture,” she said. “And they are what they are in this moment to decide about the next stage of this pandemic.”

Regardless of what the CDC decides about vaccines, millions more Americans will still be confused — including those who were given Moderna or Johnson & Johnson shots during the early stages of the vaccine rollout. The government has not yet considered boosters for these brands and doesn’t have any data on safety or effectiveness to mix-and match and give these people a Pfizer shot.

Although the COVID-19 vaccines in the U.S. offer excellent protection against serious illness, hospitalization, and death, immunity to milder infections appears to be declining months after initial vaccination.

An ambitious Biden administration plan to provide boosters to the general public was rejected by FDA. Instead, FDA is embracing a more focused approach. Dr. Janet Woodcock, acting FDA Commissioner, warned that booster decisions may change as more real-world data is available.

Woodcock stated that as we discover more about the safety and efficacy of COVID-19 vaccinations, including the use a booster dose, Woodcock will continue to evaluate rapidly changing science and keep people informed.