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Late But Great? Johnson & Johnson’s Vaccine Might Have A Few Key Advantages Over Front-runners

By Marcus Tan, Edited by Sami Morse and Maura McDonagh

Johnson & Johnson, in partnership with Harvard Medical School’s Beth Israel Deaconess Medical Center, began vaccine development in early January 2020. It is the fourth vaccine to enter Phase 3 clinical trials in the United States, the other three being developed by Astra-Zeneca, Moderna, and Pfizer. In addition to funding by Johnson & Johnson, the vaccine’s development has also received $456 million in support from the Biomedical Advanced Research and Development Authority (BARDA), which is part of the U.S. Department of Health and Human Services.

The vaccine is a viral vector vaccine meaning it uses a genetically modulated variant of the common cold virus to carry a SARS-CoV-2 gene to human cells, provoke an immune response against the corresponding SARS-CoV-2 protein, and prime the immune system to fight off later potential infection with the coronavirus.

Combined Phase 1 and 2 trials began in July and were completed by September. The trials were randomized, double-blind, placebo-controlled, involving 402 healthy adults aged 18-55 years and 394 healthy elderly adults aged more than 65 years. The trial results were mostly positive and effective, as researchers found that the levels of SARS-CoV-2 specific antibodies induced by Johnson & Johnson’s vaccine were close to the recorded levels of individuals who had recovered from infection. Furthermore, antibodies specific for SARS-CoV-2, which help the immune system identify and clear the virus, were comparable between younger and older adults, among those vaccinated. Adverse effects were local and mild, the most common being pain around the injection site along with fatigue, headaches, and muscle aches, side effects consistent for most vaccines, including the flu shot.

Dr. Anthony Fauci stated in late September that “the [Johnson & Johnson] candidate has showed promise in early-stage testing and may be especially useful in controlling the pandemic, if shown to be protective after a single dose.”


Phase 3 trials began in early-September involving about 60,000 participants in the United States, Argentina, Brazil, Chile, Columbia, Mexico, Peru, and South Africa. The size makes it the largest Phase 3 trial of the four vaccine candidates in the United States. However, it has not proceeded without disruption. Trials were paused for 11 days, beginning on October 12, after a participant reported a serious medical event. After evaluation, Johnson & Johnson said in a statement that, although “no clear cause has been identified,….[Johnson & Johnson] has found no evidence that the vaccine candidate caused the event.” As of October 23, the trials have restarted and Johnson & Johnson stated there would likely be little to no delay in the development timeline, with results being expected by early 2021.

While the vaccine has entered Phase 3 trials months after the leading vaccines by Moderna and Pfizer, it has the potential to lead us out of this pandemic, even as a late-comer. Its main advantage over Moderna and Pfizer is that it would require only one shot to be effective, compared to two shots at different times. This would ease the production requirements. It would also make it simpler to vaccinate millions of people, making rapid, mass vaccination more achievable, and increase compliance. Furthermore, while it has to be frozen during transport, the vaccine can be stored in a liquid form in refrigerators whereas the Moderna and Pfizer vaccines must be kept frozen or at very low temperatures until shortly before being administered. This makes the Johnson & Johnson vaccine better-suited to serve more isolated, rural populations in developing countries and medical deserts where infrastructure challenges make it difficult for large numbers of doses to be safely transported in ultra-cold storage. Reflecting these potential advantages, Johnson & Johnson signed a $1 billion contract with the US government to supply 100 million doses, if approved.


Results from ongoing research and the current understanding of COVID-19 are constantly evolving. This post contains information that was last updated on November 7, 2020.

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