(CNN)Internal discussions at the US Food and Drug Administration have centered around an early September timeline for laying out a strategy on Covid-19 vaccine booster shots, a Biden administration official told CNN.
The strategy would apply for all vaccinated people. A decision for those who are immunocompromised and face greater risk from the virus is expected sooner, the official said Thursday.
The US has not yet recommended booster shots for individuals who have been vaccinated for Covid-19. But Biden administration officials have repeatedly asserted that if a booster shot is recommended, the US will have the supply, personnel and capacity to roll it out efficiently.
The Wall Street Journal first reported on the expected September timeline.
An FDA spokewoman told CNN in a statement that the FDA, along with the US Centers for Disease Control and Prevention and the National Institutes of Health, are evaluating potential solutions to questions on the use of booster doses of Covid-19 vaccines.
"The agencies are engaged in a science-based, rigorous process to consider whether or when a booster might be necessary," FDA spokesperson Abby Capobianco said in a statement
Capobianco said "in the near future" the FDA will share information on potential options for immunocompromised people, who face a greater risk from the virus than healthy people.
The decision to move forward on a plan for boosters comes as the country continues to deal with the contagious Delta variant of Covid-19, which has sent cases and hospitalizations surging primarily among unvaccinated individuals.
The Biden administration has struggled to reach its goals in getting the eligible American population vaccinated against Covid-19. And in recent weeks, the President has pivoted his White House's approach to getting more people vaccinated, offering cash incentives, instituting a vaccine requirement for federal workers and encouraging other states and cities to follow in New York City's footsteps with a vaccine requirement for certain businesses or venues.
The daily pace of Covid-19 vaccinations, meanwhile, is the highest it's been in nearly seven weeks, according to data from the US Centers for Disease Control and Prevention. As of Thursday, 49.9% of the eligible US population is fully vaccinated.
The World Health Organization on Wednesday called for a moratorium on booster shots until at least the end of September, to enable at least 10% of each country's population to be vaccinated. But despite the organization's global call, Germany, France, Israel, and the UK have all indicated that they will be forging ahead with plans to begin administering Covid-19 booster shots starting in, or before, September.
While he did not speak on timing of a booster shot recommendation, US Surgeon General Dr. Vivek Murthy suggested on Wednesday that the country is capable of contributing to the global vaccination effort while still providing vaccines to Americans -- even potential booster doses.
"I recognize why the WHO has raised this concern, they are concerned about the whole world and frankly, we are too, because we will not get through this pandemic unless we make sure that countries around the world have enough vaccine to make sure that cases come down and stay down," Murthy told MSNBC. "If there's uncontrolled spread of the virus in another country that means variants can arise, those can end up here in the United States, we don't want that."
"But I don't think we need to necessarily choose between vaccinating the rest of the world, and providing the vaccinations, including potentially boosters if they're required, that our country needs," Murthy said.
Dr. Anthony Fauci, the head of the National Institutes for Allergies and Infectious Diseases, said on Tuesday that people with compromised immune systems may need additional protection after receiving a Covid-19 vaccine, and there is an effort to make vaccine boosters available to that population "very soon."
Vaccine advisers to the CDC have met to discuss whether immunocompromised people may need additional protection from a vaccine booster, but have not yet presented a formal recommendation or voted on guidance.
"We are trying very hard to get the regulatory mechanism in place very soon to get those individuals a boost that might bring up their immunity to the level where it should be, if possible," Fauci added.
Moderna's Covid-19 vaccine showed 93% efficacy against symptomatic disease through six months, and the company expects to complete its application for full approval from the FDA this month, the company said Thursday. And in July, the makers of another mRNA vaccine authorized in the US, Pfizer/BioNTech, released efficacy data showing an overall six-month efficacy of 91% -- with possible waning toward the end of that time. Like the Moderna data, the Pfizer follow-up data was collected prior to the Delta-related surge.
Moderna believes the Delta variant will lead to more breakthrough infections and that boosters may be needed before winter, according to slides published ahead of the company's earnings call on Thursday.
Pfizer said in an investor call last week that it intends to submit a booster for emergency use authorization consideration as early as August.
This story has been updated with additional information.
