A handful of other vaccines in the US - including shots made by Moderna Inc. and Pfizer Inc. - and others in other countries are already in final-stage testing. The board has asked for more information, he said, adding that the company is collecting information to answer its questions.
"It'll be a few days at minimum for the right set of information to be gathered and evaluated", Mammen said. The trial pause "is a good thing and a normal thing", she said.
The Johnson & Johnson phase 3 trial of its Janssen COVID-19 vaccine candidate involves an anticipated 60,000 adults in multiple countries, testing the safety and efficacy of a single dose versus a placebo.
"If a medication is studied in one group, but then it's being used by another more diverse group, can you say the effects are the same in the study group, then the group actually using the drugs?"
"Even if we had enough vaccine for everyone, it's unlikely that ... the physical distancing rules can be just dropped", Prof Andrew Pollard told the Daily Mail.
This is not the only occasion a Covid-19 vaccine trial has been paused for safety concerns.
The company doesn't know much yet, he said, since it is up to the independent monitoring board to look into it. While AstraZeneca's trials in Britain, Brazil, South Africa and India have since resumed, its US trial remains on hold.
It uses the human adenovirus ― which causes the common cold ― to deliver part of the spike protein of the SARS-CoV-2 virus into cells to stimulate antibodies.
BARDA has committed up to almost $1.5 billion toward supporting JNJ-78436735, from development through licensure-an award of more than $456.2 million in February, followed August 5 by approximately $1 billion to support a manufacturing demonstration project including the ability to deliver vaccine doses to government-designated locations nationwide.
The prospect of a Covid-19 vaccine by year's end has been a feature of political campaigns in the US and fueled hopes for the reopening of countries in Europe and elsewhere. The laboratories concerned are Moderna, Pfizer and BioNTech, CanSino Biologics, the. European Medicines Agency executive director Guido Rasi said last week that a vaccine was looking unlikely by year end.
This is not the first coronavirus vaccine trial to be placed on pause.
Final-stage testing of a vaccine made by AstraZeneca and Oxford University remains on hold in the U.S.as officials examine whether an illness in its trial poses a safety risk.