Buoyed by positive results in its earlier studies, Johnson & Johnson has begun the final stage of clinical trials for its coronavirus vaccine.
Although they are a couple of months behind the other so-called Phase 3 trials in the United States, Johnson & Johnson’s trials will be the largest, with plans to enroll 60,000 participants and the experimental vaccine may have considerable advantages over some of its competitors according to experts.
It does not need to be stored in subzero temperatures, and it may require just one dose instead of two.
According to Dr. Judith Feinberg “It would be fabulous if we had something at a single dose,” said Dr. Judith Feinberg, the vice chairwoman for research in medicine at West Virginia University, who was not involved in the study.
Only a Phase 3 trial, which compares the effects of a vaccine with those of a placebo, could determine if a single dose was indeed effective, Feinberg said.
But if it worked, that could greatly speed efforts to curb the pandemic.
The trial started on Monday. At a news conference on Tuesday, Dr. Paul Stoffels, chief scientific officer of Johnson & Johnson, said the company might be able to determine by the end of the year if the vaccine is safe and effective.
He said the company will soon be posting a manuscript online with data from the earlier phases of its trials.
Johnson & Johnson’s experimental vaccine uses an adenovirus to carry a gene from the coronavirus into human cells.
The cell then produces coronavirus proteins, but not the coronavirus itself.
These proteins can potentially prime the immune system to fight off a later infection by the virus.
Adenovirus vaccines must be kept refrigerated but not frozen, unlike the two front-runner vaccines, by Moderna and Pfizer, which depend on bits of genetic material known as mRNA.
The freezing requirement could make the distribution of those vaccines difficult, especially to places without advanced medical facilities.
Moderna and Pfizer’s vaccines also require two jabs given a few weeks apart, a significant logistical hurdle.
A virologist from the Beth Israel Deaconess Medical Center Dr. Daniel Barouch said the single jab vaccine if it proves effective will be a game-changer and remove a major logistic hurdle.
Barouch led the development of the adenovirus vaccine in the early 2000s.
Johnson & Johnson acquired it and used it to make vaccines for Ebola, H.I.V., respiratory syncytial virus and Zika.
All told, 100,000 people have received the adenovirus vaccine in clinical trials for these four diseases, without any serious side effects.
Johnson & Johnson’s Ebola vaccine was licensed in Europe in June.
In contrast, the designs for the other three coronavirus vaccines in Phase 3 trials in the United States have not yet been licensed to treat any disease.
(A different kind of adenovirus is being used in AstraZeneca’s coronavirus vaccine trials, which have been paused in the United States because of safety concerns.)