But two senior administration officials told POLITICO that the Biden administration is preparing for a potentially lengthy disruption in use of the J&J vaccine, particularly for certain groups — such as women ages 18-48, who make up all of the known clotting cases. The CDC is waiting for its independent vaccine advisory panel to make a determination on Wednesday about whether and how to restrict eligibility for the J&J shot, said the officials, who spoke on the condition of anonymity to offer a more thorough discussion of the issue.
The administration’s preparations for a potentially lengthy stoppage highlight the level of concern among senior government scientists — especially after reports of similar rare but serious reports of blood clots among recipients of AstraZeneca’s Covid-19 shot, which uses the same technology as the J&J vaccine. The situation also presents a major political challenge for the Biden administration as it tries to balance the best scientific advice with concerns that the pause could dent public confidence in vaccines or lead to further infections or deaths.
“The FDA is the gold standard for ensuring the safety and the effectiveness of the vaccines,” White House Covid-19 response coordinator Jeff Zients said at the Tuesday press conference. “And today’s action, I think, is clear evidence that they’re taking every step necessary to ensure the American people have clear and transparent information about the safety and effectiveness of these vaccines.”
Zients batted down concerns that the stoppage could significantly delay the nation’s vaccination push, arguing that the Johnson & Johnson vaccine has accounted for less than 5 percent of U.S. vaccinations to date.
He and other administration officials said there should be enough doses of vaccines from Pfizer and Moderna to vaccinate most U.S. adults by late May.
Conversations about whether to pause use of the J&J vaccine began early last week after the FDA and CDC had collected reports of individuals who received the shot experiencing severe blood clots, according to the two senior officials inside the CDC who have direct knowledge of the matter. Agency director Rochelle Walensky met with Fauci, and the FDA’s top vaccine regulator, Peter Marks, over the course of several days to analyze the data on the reported blood clots.
The White House learned of the matter on Monday night, Zients said Tuesday.
The concern, the two senior CDC officials said, is that there may be additional cases of the blood clots — a type known as cerebral venous sinus thrombosis — and that the agencies needed more time to track down those cases and analyze the data more completely. Federal officials also emphasized that they need time to educate medical personnel about the best way to treat this type of clot, which is different from the standard approach to clotting.
The CDC officials said that administration scientists determined the data they did have was enough to justify a temporary pause in the use of the vaccine, particularly because the Pfizer and Moderna shots would still be available. Both companies have made production improvements in recent months that have increased the pace of their vaccine deliveries to the U.S. government.
In the meantime, the CDC and the FDA are continuing to study the data and collect additional information about the scope of the problem and whether the blood clots are impacting a wider population than originally understood, the two CDC officials said.
Marks told reporters Tuesday that it is likely the government will receive more reports of blood clots in people who have gotten the J&J vaccine, as doctors and patients learn more about the symptoms.
Rachel Roubein, Sarah Owermohle and David Lim contributed to this report.