A third vaccine has been added to the arsenal against the COVID-19 pandemic, as the FDA approved the Johnson and Johnson (J&J) COVID-19 vaccine at the end of February. The Emergency Use Authorization (EUA) approval was based off two months of safety and efficacy data from their Phase 3 ENSEMBLE study, with full approval pending additional safety data.
The ENSEMBLE study was a double-blinded, placebo-controlled study of about 40,000 participants on three continents. Half of the participants received the single-dose vaccine, and half received a placebo. The US enrolled 44% of the trial’s participants, who were diverse and representative of the country’s population. Additionally, 41% participants in the study had comorbidities associated with an increased risk for progression to severe COVID-19.
The vaccine was found to be 66.9% effective at preventing moderate to severe/critical COVID-19 14 days after the single-dose vaccine, and 66.1% effective 28 days afterward. In the US, the vaccine was 85.9% effective against severe forms of COVID-19, and was proven to have a strong protective effect against hospitalizations and death. There were no hospitalizations or deaths starting 28 days after vaccination across all U.S., Brazilian, and South African sites that received the vaccination. Additionally, the vaccine was 81.7% effective against severe forms of COVID-19 in South Africa—suggesting that the vaccine may protect patients against the highly transmissible B.1.351 variant.
The J&J vaccine, as with the vaccines developed by Pfizer and Moderna, was not tested in children under the age of 18 or pregnant women and is currently not approved for these populations. Trials are planned for these populations.
There has been much discussion about the relative differences among the vaccines. The most notable differences involve the technology and the dosing. The Pfizer and Moderna vaccines are based off of mRNA technology, whereas the J&J vaccine is based off of the Janssen ADVAC technology platform. The technology, which was successfully utilized in the vaccine for Ebola, uses a modified form of an adenovirus (the common cold) to introduce the genetic information cells need to produce the spike protein. The vaccine is administered via one dose, as opposed to the Pfizer and Moderna vaccines, which require two doses.
While there has been discussion comparing the different vaccines based on their relative efficacies, there are a number of factors that do not allow for direct comparison or make one vaccine superior to the others. Efficacy data can differ because the trials were held at different times during the course of the pandemic, where the impact of the disease on different populations varied greatly. Laboratory conditions are nearly impossible to replicate during a pandemic, and clinical interventions improved greatly over the course of 2020 as clinicians and health officials learned more about how the virus behaves.
The powerful protective effect secured after a single dose, coupled with the economy of production, minimal storage requirements, and a higher perceived sense of safety from an adenovirus-based technology makes this vaccine an incredible addition to the suite of vaccines currently available and an optimal choice for certain parts of the world.
The success of a vaccine cannot be achieved through clinical innovation alone. It also requires thoughtful commercialization, beginning with and understanding the patient voice from the beginning of their COVID-19 vaccine journey. Awareness campaigns must accompany the clinical endeavors to ensure that all populations feel confident and safe taking them. Sponsors and their stakeholders must engage with populations early to gain buy-in (especially from those who have been historically underserved) to ensure maximum adoption for this vaccine and future campaigns.