The Data and Safety Monitoring Panel, an independent group of experts that oversees clinical trials in the US to ensure the safety of participants, recommends suspending a clinical trial if there is an "adverse event," said Isaac Bogoch, infectious disease specialist and professor at the University of Toronto. The hiatus will last until all of the information is gathered and doesn't necessarily mean there's a problem with the vaccine or treatment, he said.
"The DSMB will say we need to take a break," said Bogoch, who is also a member of the group overseeing other clinical drug trials. “They'll say, 'We need more data and want to see if that person was in the vaccine group or in a placebo group.' They'll say, 'Let's see what the real disease is, and using all the data we have to determine whether this was a real side effect of the vaccine, and if so, whether it is safe to proceed with this study. "
According to Dr. Paul Offit, director of the Vaccine Education Center at the Children's Hospital in Philadelphia, has a constant pause, especially in large clinical trials in older adults.
Offit, a former member of the CDC Advisory Committee on Immunization Practices, said "adults get sick" and sometimes "they get sick" in the same amount of time when they receive a vaccine or treatment.
"The Johnson & Johnson vaccine is supposed to prevent Covid-19. It's not supposed to prevent everything else that happens in life," he said. "They are always going to sort out those temporal associations. Strokes, heart attacks, neurological problems. Always. You are always careful and make sure this is not a problem and then move on again."
Bogoch repeated these remarks, adding, "Before Covid-19, no one cared if a clinical trial for an antibiotic or a heart drug was interrupted."
"We have never been in a scenario where 7 billion people are really watching and watching every single progress under the microscope," he said. "You know, it's fascinating and good. It creates a community with more health literacy. There is only good that can come out of it."
He added that a pause is not synonymous with a regulatory hold, sometimes referred to as a "clinical hold". A clinical lockdown is imposed by a health agency such as the Food and Drug Administration, he said.
"It's a little more serious when you get to a regulatory standstill," he said. "At that moment the FDA steps in and says we are concerned about a certain event and we are going to stop this study because we don't think it's safe to proceed with the data we have at this point To be available. ""
The FDA has yet to suspend a late-stage clinical trial of AstraZeneca, a leader in the Covid-19 vaccine race, in the US. This means the company will not be able to give US participants second doses of its vaccine dose with two doses.
The company announced on Sept. 8 that its study had been suspended because of an unexplained disease in a patient in the UK. The patient is believed to have developed an inflammation of the spinal cord known as transverse myelitis. The trial has since resumed in the UK and other countries, but is still on hold in the US.
It is not known what reactions the participants in the experiments of J&J and Eli Lilly had.
Offit said companies sometimes claim they are protecting the patient's confidentiality, but he disapproved of the behavior. "Until you can identify the person, they can give you a whole lot of information about the person, but they don't," he said.
Dr. Mathai Mammen, global director of research and development at J & J in Janssen, told investors in a conference call Tuesday that the company still had "very little information" about the reason for the delay, even if the patient had the vaccine or received the placebo. "It will take at least a few days to gather the right information," he added.
Dr. Ezekiel Emanuel, a former health advisor in the Obama administration, said it would "raise serious questions" if the participant were given the vaccine.
"An adverse event is serious, especially when you are considering a vaccine that you are about to roll out to tens, hundreds of millions, maybe billions," he said on CNBC's Squawk Box on Tuesday. "That is the ultimate concern."
Eli Lilly and the National Institutes of Health also did not disclose what the "safety concern" was, but Eli Lilly said it supported "the decision of the independent DSMB to carefully ensure the safety of patients in this study."
"Security is of the utmost importance to Lilly. We understand that the independent ACTIV-3 Monitoring Board for Data Security (DSMB) has recommended that the registration be suspended as a precaution," spokeswoman Molly McCully told CNBC.