While serious adverse event are not uncommon in clinical trials, they raise concerns, especially when the vaccine development timelines are compressed, leaving less time to sufficiently analyse safety and efficacy of the drug or vaccine
Johnson & Johnson on October 13 said it has paused phase-3 trials of its coronavirus vaccine following an unexplained illness to a participant.
The company said the participant’s illness is being reviewed and evaluated by the an independent Data Safety Monitoring Board (DSMB) as well as internal clinical and safety physicians.
"We’re also learning more about this participant’s illness, and it’s important to have all the facts before we share additional information," the company said in a statement.
Frequently Asked Questions
A vaccine works by mimicking a natural infection. A vaccine not only induces immune response to protect people from any future COVID-19 infection, but also helps quickly build herd immunity to put an end to the pandemic. Herd immunity occurs when a sufficient percentage of a population becomes immune to a disease, making the spread of disease from person to person unlikely. The good news is that SARS-CoV-2 virus has been fairly stable, which increases the viability of a vaccine.
There are broadly four types of vaccine — one, a vaccine based on the whole virus (this could be either inactivated, or an attenuated [weakened] virus vaccine); two, a non-replicating viral vector vaccine that uses a benign virus as vector that carries the antigen of SARS-CoV; three, nucleic-acid vaccines that have genetic material like DNA and RNA of antigens like spike protein given to a person, helping human cells decode genetic material and produce the vaccine; and four, protein subunit vaccine wherein the recombinant proteins of SARS-COV-2 along with an adjuvant (booster) is given as a vaccine.
Vaccine development is a long, complex process. Unlike drugs that are given to people with a diseased, vaccines are given to healthy people and also vulnerable sections such as children, pregnant women and the elderly. So rigorous tests are compulsory. History says that the fastest time it took to develop a vaccine is five years, but it usually takes double or sometimes triple that time.
“Adverse events — illnesses, accidents, etc — even those that are serious, are an expected part of any clinical study, especially large studies,” the company said in the statement.
The company said they follow clinical guidlines to ensure that studies may be paused if an unexpected serious adverse event (SAE) that might be related to a vaccine or study drug is reported, so there can be a careful review of all of the medical information before deciding whether to restart the study.
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Johnson & Johnson's Covid-19 experimental vaccine is based on adenovirus vector Ad26. The company has used the same viral platform to develop vaccines for Ebola and other viruses such as Zika, RSV and HIV.
Second trial to be paused
This is second such pause of COVID-19 vaccine clinical trial.
Following a review by the UK drug regulator MHRA and an independent safety review committee, the trial resumed in all other countries except the US. In India, Serum Institute of India (SII), which has partnered with AstraZeneca, is conducting phase 2/3 clinical trials.
Incidentally, AstraZeneca vaccine too is based on adenovirus that causes common colds in chimpanzees.
Concerns of rushing vaccine
While SAEs are not uncommon in clinical trials, and the number of SAEs can reasonably be expected to increase in trials involving large numbers of participants, they raise concerns, especially when the vaccine development timelines are compressed, which may not provide enough time to sufficiently analyse safety and efficacy of the drug or vaccine.
Here is an explainer on SAE and how they are reported.
Johnson & Johnson began phase-3 trial in September with a plan to enroll 60,000 volunteers across three continents to study the safety and efficacy of a single vaccine dose versus placebo in preventing COVID-19. If proven to be safe and effective, the first batch of the vaccine should be available for emergency use in early 2021. It took just three months for the company to move from phase 1/2 to a late-stage trial.
Johnson & Johnson has partnered with Biological E to manufacture the vaccine for distribution in India and other countries.What sets it apart is that it is a one-dose vaccine compared to two for other vaccine candidates and doesn’t need to be frozen for distribution, which will make transportation easy and save costs.