The Biden administration will start rolling out COVID-19 vaccine boosters in September, offering most people another shot 8 months after vaccination

• Most people in the US will be offered a COVID-19 booster shot about eight months after vaccination.
• The plan aims to better protect Americans from the coronavirus amid a surge driven by the Delta variant.
• Some experts have said there isn't yet data showing that we need booster shots.

The Biden administration rolled out its plan Wednesday for giving booster shots of the COVID-19 vaccine, saying most people in the US will be offered another dose about eight months after their initial vaccination to bolster their protection.

The decision comes as the Delta variant fuels a coronavirus surge in the US, with the daily average of new cases over the past week hovering around 140,000 - the highest levels since February. Hospitalizations and deaths have also increased, especially in the South, though the vast majority are occurring among people who aren't vaccinated.

The booster-shot campaign will begin September 20 for people who received Moderna or Pfizer-BioNTech vaccines, government officials said. People who got the single-dose Johnson & Johnson vaccine will probably need boosters as well, though officials are still evaluating data on that vaccine.

The US Food and Drug Administration needs to authorize booster shots from each vaccine-maker before they can be rolled out. People will likely be eligible for boosters eight months after they received their second dose of the two-dose immunizations.

Booster shots will be free to individuals, and available at about 80,000 locations including pharmacies, Jeff Zients, the White House's COVID-19 response coordinator, said during a press conference. He said the US has enough vaccines to give everyone an extra dose.

US health officials leading agencies including the FDA, the Centers for Disease Control and Prevention, and the National Institutes of Health released a statement Wednesday saying the data is "very clear that protection against SARS-CoV-2 infection begins to decrease over time following the initial doses of vaccination."

"Based on our latest assessment, the current protection against severe disease, hospitalization, and death could diminish in the months ahead, especially among those who are at higher risk or were vaccinated during the earlier phases of the vaccination rollout," the public-health leaders said in the statement. "For that reason, we conclude that a booster shot will be needed to maximize vaccine-induced protection and prolong its durability.

Health officials said Wednesday the latest study results show waning effectiveness from the vaccines, particularly in preventing symptomatic illness. One new CDC study, for instance, found the Pfizer and Moderna vaccines lowered the risk of a coronavirus infection by 75% in nursing homes from March to May, before the Delta variant became dominant in the US. But from June to August, after the variant had spread widely, those vaccines only lowered the risk of infection by 53%.

While Moderna and Pfizer are both working on newer versions of their vaccines tailored to protect against Delta and other variant, these booster shots are expected to be similar to the shots that people are already receiving.

Both drugmakers have recently presented data showing that booster shots can increase the immune system's ability to fend off the Delta variant.

The decision comes amid an ongoing debate over whether or not booster shots are needed. Some vaccine experts have said there isn't enough data to justify giving boosters now, and the vaccines are still highly effective at preventing hospitalizations and deaths. They also contend that the goal should be to get initial vaccine doses to more people, both in the US and around the world.

On the other side, executives at vaccine-makers Pfizer and Moderna have argued it's best to be proactive. As Moderna CEO Stéphane Bancel has repeatedly put it, he'd rather have the US offer boosters two months too early than two months too late.

Health workers and vulnerable people to get boosters first

By tethering booster shots to the time of initial vaccination, the booster campaign will follow a similar sequence to the initial rollout of shots: healthcare workers, as well as the elderly and other vulnerable people first, followed by younger and healthier populations.

It's unclear how many vaccinated people will decide to get a booster; Michael Yee, a biotech analyst at Jefferies, estimated in an August 10 research note that about 30% of immunized people would get a booster.

The US has already started offering booster shots to a small group of people with weakened immune systems. Those shots are only available to people who were initially vaccinated with shots from Pfizer-BioNTech or Moderna.

About nine in 10 fully vaccinated Americans received two doses of either the Moderna or Pfizer-BioNTech vaccines, which both use a similar technology.

Nearly 14 million people in the US received the single-dose J&J vaccine. The health officials said they expect data that will help them decide on a booster-shot plan for people who received that vaccine in the next few weeks.

To date, the US has administered more than 357 million doses of COVID-19 vaccines. About 169 million people in the US are fully vaccinated, or just over half of the nation's population. Children younger than 12 still aren't eligible to get coronavirus vaccines.