J&J’s single-shot Covid-19 vaccine: the journey to approval
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J&J’s single-shot Covid-19 vaccine: the journey to approval

By Kezia Parkins 15 Mar 2021 (Last Updated April 15th, 2021 16:41)

J&J’s single-shot Covid-19 vaccine has received emergency authorisation in both the US and EU. What has been the vaccine candidate’s journey from early development to approval?

J&J’s single-shot Covid-19 vaccine: the journey to approval
J&J’s single-shot Covid-19 vaccine has received emergency authorisation in both the US and EU. Clinical Trials Arena looks at the vaccine’s journey to approval. Image credit: Shutterstock

Last week, hot on the heels of an FDA emergency use authorisation (EUA), Johnson & Johnson (J&J) subsidiary Janssen’s Covid-19 vaccine became the fourth Covid-19 vaccine to be recommended for use in adults in the EU following vaccines produced by Pfizer/BioNTech, Moderna and AstraZeneca/Oxford. Like the AstraZeneca/Oxford vaccine, the product is adenovirus-based and relies on Janssen’s proprietary AdVac platform.

The J&J vaccine is the first one-and-done approved jab, designed to be effective after a single dose. The other approved vaccines require two doses spaced over a number of weeks for optimal immunisation.

Clinical Trials Arena tracks the journey to approval for the world’s first single-shot Covid-19 vaccine, from its origins at the outset of the pandemic to its landmark approvals in early 2021.

January 2020: sequencing the novel coronavirus

In January 2020, just as the pandemic started to take hold, J&J obtained the novel coronavirus’s sequence information from China and validated it.

From there, the company worked closely with Dr Dan Barouch and his team at the Center for Virology and Vaccine Research at the Beth Israel Deaconess Medical Center, an affiliate of Harvard Medical School, to design a large number of potential candidates for the vaccine. The company had previously collaborated with Barouch on preclinical work for its Zika and HIV vaccine candidates.

“Due to our extensive previous experience with vaccine technology – we used the same technology to create our European Commission-approved Ebola vaccine – scientists already had a good sense of the best doses to use for the investigational Covid-19 candidate,” said J&J global head of Janssen research & development Dr Mathai Mammen.

March 2020: funding J&J’s early research

In March 2020 J&J announced a “landmark partnership” with the Biomedical Advanced Research and Development Authority (BARDA), a component of the Office of the Assistant Secretary for Preparedness and Response in the US Department of Health and Human Services, to commit equally to more than $1 billion to co-fund research, development and clinical testing for a potential Covid-19 vaccine.

This announcement also came with the news that, after experimenting with various candidates, a clear leader had emerged, with two back-ups.

September 2020: the ENSEMBLE trial begins

After signing a “historic pledge to uphold the integrity of the scientific process in developing an investigational Covid-19 vaccine” on 23 September, Johnson & Johnson announced the launch of its large-scale, pivotal, multi-country Phase III trial (ENSEMBLE) for its lead candidate, JNJ-78436735, being developed by Janssen Pharmaceutical Companies.

The initiation of the ENSEMBLE trial followed positive interim results from the Company’s Phase I/IIa clinical study, which demonstrated that the candidate’s safety profile and immunogenicity after a single vaccination were supportive of further development.

October 2020: ENSEMBLE resumes after safety-related pause

In October, Johnson & Johnson announced that it was preparing to resume recruitment in the pivotal Phase III ENSEMBLE trial of its investigational Janssen Covid-19 vaccine in the US after a temporary pause.

The halt in progress was down to a “serious medical event” in one of the trial participants.

No clear cause for the adverse event was identified. The company said there were many possible factors that could have caused the event and that based on the information gathered to date and the input of independent experts, no evidence had been found indicating that the vaccine candidate was behind it.

December 2020: ENSEMBLE fully enrolled

By 17 December 2020, the ENSEMBLE trial was fully enrolled with approximately 45,000 participants.

The company also confirmed that a separate Phase III clinical trial to explore a two-dose regimen of Janssen’s vaccine candidate (ENSEMBLE 2) is ongoing.

January 2021: key results from ENSEMBLE trial

On 29 January 2021, J&J announced that the single-shot Janssen Covid-19 vaccine candidate met primary endpoints in the interim analysis of its Phase III ENSEMBLE trial.

The shot’s overall observed efficacy was 66% protection against moderate Covid-19 disease and 85% protection against severe disease.

Notably, it was found that efficacies differed at different trial locations: 72% efficacy in the US, 66% in Latin America, and 57% in South Africa – in the case of South Africa, the reduced efficacy is thought to have been caused by a new SARS-CoV-2 variant, B.1.351.

J&J’s Phase III trial results came hot on the heels of those of Novavax’s new vaccine.

GlobalData analysts concluded that J&J’s single-shot Covid-19 vaccine would be best used to control outbreak, with its single-dose administration suited to immunising large groups as quickly as possible. Novavax’s vaccine, meanwhile, showed more potent protection with efficacy of 89.3% after two doses.

February 2021: US emergency authorisation

On 24 February 2021, FDA scientists endorsed J&J’s single-shot Covid-19 vaccine, encouraged by new data providing further evidence of its efficacy at preventing hospitalisations from the disease.

On 27 February the FDA issued an emergency use authorisation (EUA) for J&J’s one-and-done vaccine, allowing the Janssen COVID-19 Vaccine to be distributed in the US for use in individuals 18 years of age and older.

“The authorisation of this vaccine expands the availability of vaccines, the best medical prevention method for Covid-19, to help us in the fight against this pandemic, which has claimed over half a million lives in the United States,” said acting FDA commissioner Janet Woodcock. “The FDA, through our open and transparent scientific review process, has now authorised three Covid-19 vaccines with the urgency called for during this pandemic, using the agency’s rigorous standards for safety, effectiveness and manufacturing quality needed to support emergency use authorisation.”

March 2021: EU emergency authorisation

On 11 March, the European Medicines Agency (EMA) recommended conditional marketing authorisation for Janssen’s Covid-19 vaccine in the EU.

The recommendation came after a thorough evaluation by the EMA’s Committee for Medicinal Products for Human Use of clinical trial data submitted by J&J in December. The committee concluded that the data for the vaccine was robust and met the criteria for efficacy, safety and quality.

Shortly afterwards, the European Commission (EC), the EU’s executive body, confirmed the approval. The bloc has struggled to kickstart the rollout of vaccines across the continent and has been embroiled in disputes with various companies and countries over vaccine export issues in recent weeks, so another approved vaccine for distribution will come as some relief to European health authorities.