(CNN) Despite repeated claims they're committed to transparency, Johnson & Johnson and the US Food and Drug Administration still aren't revealing crucial details one week after the pharmaceutical giant's Covid-19 vaccine trial went on pause.
Public health experts have encouraged transparency in the Covid-19 vaccine clinical trials, considering that hundreds of millions of Americans will eventually be asked to roll up their sleeves and take a vaccine.
The Johnson & Johnson trial was put on hold October 12 due to a study participant's "unexplained illness," according to a company statement last week. Johnson & Johnson voluntarily stopped enrolling study participants while the illness is being reviewed by an independent monitoring board.
The company and the FDA declined to answer two questions from CNN: One, whether the study volunteer who became ill received the vaccine or the placebo, and two, if this is the first pause for the trial.
The answers to both questions are critical to understanding what this participant's illness might mean for the safety of a vaccine.
Dr. Paul Offit, a member of an FDA advisory committee that will review the vaccines, said Johnson & Johnson should answer these basic questions.
"The goal is to inform the public. When you don't, it causes people to imagine the worst," said Offit, a member of the FDA's Vaccines and Related Biological Products Advisory Committee.
Dr. Peter Hotez, director of the Center for Vaccine Development at Texas Children's Hospital, agreed, noting that polls show many Americans don't want to get a Covid-19 vaccine once one goes on the market.
"By shrouding this in secrecy and leaking things out in bits and pieces, it somehow conveys the message that something untoward is happening," Hotez said.
FDA Commissioner Dr. Stephen Hahn has written about the importance of transparency in the Covid-19 vaccine development process.
"We believe transparency in this process will help build public confidence & provide greater understanding of FDA's work," Hahn tweeted on September 15.
Spokespersons for his agency declined to answer CNN's questions about Johnson & Johnson's trial, saying, as it has with other trials, that federal regulations prohibit the agency from disclosing information. The agency referred CNN to Johnson & Johnson.
The pharmaceutical company has also said it's committed to transparency, including transparency about its Covid-19 vaccine trial.
"At Johnson & Johnson, we believe the transparency of clinical trial data advances science and medicine and is in the best interest of the patients and consumers who use our pharmaceutical products and the healthcare professionals who prescribe them. We support the overall principles of clinical trial data transparency with the goal of advancing medical sciences," according to a statement on the company's website.
When asked questions about the Covid-19 trial pause, a Johnson & Johnson spokesman referred CNN to statement from October 12, when it announced the pause.
In an email to CNN, the spokesman, Jake Sargent, highlighted this sentence from the statement: "We're also learning more about this participant's illness, and it's important to have all the facts before we share additional information."
It shouldn't take a week to determine whether a study participant received the vaccine or a placebo, according to vaccine specialists.
The Johnson & Johnson trial started September 23, with the intention to recruit 60,000 patients in eight countries, including the United States.
The company learned of the study volunteer's "unexplained illness" on Sunday, October 11, Dr. Mathai Mammen, global head of research and development at Janssen Pharmaceuticals, a division of Johnson & Johnson, said Tuesday on the company's third-quarter earnings call.
In the study, half of the participants receive the vaccine and half receive the placebo, which is a shot of saline that does nothing. The study is blinded, which means the company doesn't know who receives which, and neither do the participants or the doctors running the trial.
If the participant who became ill received the placebo, that means nothing for the trial. If the participant received the vaccine, however, that could raise safety questions.
Only the trial's Data Safety and Monitoring Board, a group of independent scientists, can unblind the status of the ill participant and find out if he or she received a vaccine or placebo.
"They could find that out very quickly, certainly within 24 hours," said Dr. Jesse Goodman, director of the FDA's Center for Biologics Evaluation and Research from 2003 to 2009, and the agency's chief scientist from 2009 to 2014.
When CNN asked whether the volunteer received the vaccine or the treatment, the Johnson & Johnson spokesman pointed to the company's October 12 statement, which notes that "as many trials are placebo-controlled, it is not always immediately apparent whether a participant received a study treatment or a placebo."
On October 13, on the earnings call, Mathai, the Johson & Johnson executive, said the company had shared data with the monitoring board.
"We've given our information set that we do know to the DSMB, and they've asked a number of specific questions. We don't know whether -- they haven't informed us of their -- they have the right to unblind. We are still blinded. So we don't know treatment arm, vaccine arm," he said.
Wednesday, Johnson & Johnson's chief financial officer repeated that the company didn't know what the volunteer received.
"We don't know even at this point whether that individual is in the placebo arm or the vaccinated arm," Joseph Wolk told CNN's Richard Quest.
It's unclear if Johnson & Johnson has learned since Wednesday whether the participant received the vaccine or placebo.
"It certainly is possible the DSMB is investigating and the company is still unaware of what group they're in, and it would be helpful if they would clarify that," Goodman, the former FDA official, said.
Offit said it's clear to him that the participant received the vaccine -- otherwise the trial wouldn't have been put on hold and stayed on hold for a week.
"Why would you pause a trial if the person received the placebo? It just doesn't make sense," said Offit, the director of the Vaccine Education Center at Children's Hospital of Philadephia.
"I find it hard to believe that they have hundreds of investigators in this trial that will have 60,000 participants, this huge steamship moving forward, and you stop because a participant who received the placebo got sick? That just defies logic."
Johnson & Johnson and the FDA also declined to answer whether this was the first pause for its Covid-19 vaccine trial.
The answer is important, because if two or more participants develop similar illnesses after receiving the vaccine, that's an important red flag that the vaccine could pose safety risks.
Speaking generally about vaccine trials, former FDA Commissioner Dr. Peggy Hamburg said openness is important.
"Transparency is always better, especially with basic and straightforward questions," she said.
Participants who took a similar vaccine made by another company have also become ill.
The Johnson & Johnson vaccine and the AstraZeneca vaccine both use an adenovirus as part of its Covid-19 vaccine. Adenoviruses cause the common cold and other illnesses, but the viruses are genetically modified so they won't replicate and cause disease, according to the companies.
Volunteers in the trial run by AstraZeneca and the University of Oxford developed "unexplained neurological symptoms including changed sensation and limb weakness," according to a participant information sheet from the university.
The AstraZeneca trial paused once in July and again in September because of illnesses. The September pause is still in effect in the United States.
Offit said the pharmaceutical companies should inform the public of pauses, and if the trial is allowed to proceed, explain why the illnesses were coincidental and not due to the vaccine.
"You can inform them in a manner so people don't assume that something bad happened, so they don't assume the worst and think 'this makes me really hesitant to take this vaccine,' " he said.