A coronavirus vaccine developed by Johnson & Johnson could potentially clear U.S. regulatory hurdles over the next day, and authorization would mark the third jab in the country’s arsenal against the novel virus.
But how do the shots compare?
While previously authorized vaccines developed by Moderna and Pfizer-BioNTech operate on a newer platform with mRNA, or messenger RNA, technology, Johnson & Johnson’s candidate involves a more traditional modified adenovirus vector vaccine with a durable protein exterior encasing the DNA, lending itself to a longer shelf-life.
While Pfizer and Moderna’s vaccines each require a two-dose regimen, Johnson & Johnson’s candidate needs just a single dose, which helps to ease logistics.
Late-stage clinical trials showed Pfizer’s vaccine was 95% protective against severe COVID-19 disease, while Moderna had 94.1% efficacy and Johnson & Johnson’s candidate had a 66.9% efficacy. However "efficacy" under controlled conditions in clinical trials is not the same as "effectiveness" in imperfect real-world conditions. Results this week showed Pfizer’s vaccine was 94% effective in a study conducted in Israel involving some 1.2 million people, consistent with the high efficacy reported during clinical trials.
Further, Johnson & Johnson’s vaccine candidate is stable for up to two years at -20 degrees Celsius and at least three months at 2 to 8 degrees Celsius. Moderna’s vaccine can last at -20 degrees Celsius for six months and 2 to 8 degrees Celsius for 30 days. Meanwhile, the FDA just eased permitted shipping and two-week storage temperatures for the Pfizer vaccine to -25 degrees Celsius to -15 degrees Celsius in a significant shift from an ultra-cold temperature requirement of -80 degrees Celsius and -60 degrees Celsius for up to 6 months.
Pfizer’s vaccine was authorized for use in people 16 years and older, while Moderna’s was approved for those 18 and up, like Johnson & Johnson's candidate if the FDA finds it safe and effective. Companies are now assessing the vaccines in younger age groups.