The plan would be subject to a US Food and Drug Administration evaluation of the safety and effectiveness of a third dose and a review by the Advisory Committee on Immunization Practices, a CDC advisory panel, officials said.
Kristen Nordlund, the CDC spokeswoman, said there may have been confusion over what Pfizer, which has begun submitting an application to the FDA for its booster shots, recommends for the timing of its boosters and the plan federal officials ultimately approve.
“Last week, the administration recommended boosters at eight months,” she reiterated. “All of that is contingent upon regulatory decisions by FDA and recommendations by ACIP.”
“Six months, eight months, it’s all going to depend on a thorough review of the evidence by FDA as well as ACIP,” she said. Pfizer can “put in their application whatever they think the timing should be,” but whether that timing is approved by federal officials has “yet to be seen.”
An FDA spokeswoman declined to comment.
FDA, CDC, and other top federal officials are concerned about the effectiveness of vaccines against severe disease declining in the coming months.
“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. For that reason, we conclude that a booster shot will be needed to maximize vaccine-induced protection and prolong its durability,” the officials said in a statement last week.
Officials said they also anticipated that booster shots would be needed for people who received the Johnson & Johnson vaccine, but they were waiting for more data. (Johnson & Johnson said this week it had found its booster produced a rapid and strong increase in antibodies.)
“Our plan is to protect the American people, to stay ahead of this virus,” CDC Director Dr. Rochelle Walensky said at a media briefing last week.
Asked about the Wall Street Journal report, White House spokesman Jen Psaki said at a briefing Wednesday that “the CDC just put out the guidance … And if they update that guidance, it would certainly come directly from them.”
Dr. Paul Sax, clinical director of the Division of Infectious Diseases, at Brigham and Womens Hospital, said, “Once the decision is made to give a booster, then the difference between six and eight months isn’t sufficient to warrant making a big deal over this change.”
More important, he said, is making sure the boosters get to “the highest risk and/or vulnerable people – the immunocompromised, very elderly, multiple medical problems, healthcare and other frontline workers.”
“It does appear from the data that there has been some diminution in vaccine effectiveness over time, mostly related to prevention of infection, and to a lesser extent, prevention of symptomatic disease,” he said in an e-mail. But he noted that “prevention of hospitalization and death is still very strong at this point.”
He said that those who get a booster not only will have their health protected but will be less likely to get a breakthrough infection and spread the virus, which “potentially helps those they live and work with. In that sense, it’s a win-win from both the personal and public health perspective.”
Dr. David Hamer, a physician at Boston Medical Center and a Boston University epidemiologist, said, “The limited evidence we have right now suggests that vaccine effectiveness is starting to wane after six months. … Somewhere in the 6- to 9-month range is probably ideal for boosting and with Delta sooner may be better.”
Material from Globe wire services was used in this report.
Martin Finucane can be reached at [email protected].