If effective, Johnson & Johnson’s one-dose vaccine could quickly help large swaths of the United States develop immunity to COVID-19. That would be a game changer.

The United States’ COVID-19 vaccine rollout has been nothing short of a disaster, but there is some hope on the horizon. That includes $8 billion in federal funding making its way to states, mass vaccination sites opening across the country, and a science-first president just one week from taking over the White House. 

Perhaps most importantly, however, the US could be weeks away from approving a third coronavirus vaccine. If approved, the Johnson & Johnson vaccine could be a game-changer that helps the US reach herd immunity faster. 

When Will We Know the Results of the Johnson & Johnson COVID Vaccine Phase 3 Trial?

Johnson & Johnson hopes to release results from the final stage of its COVID-19 vaccine trial before the end of January. If the data shows that it can strongly protect people against COVID-19, as some scientists believe it will, it could play a critical role in America’s quest to end the pandemic. 

Why Is the Johnson & Johnson Vaccine a Potential Game Changer for US COVID vaccinations?

Unlike the already-approved vaccines from Moderna and Pfizer, the Johnson & Johnson vaccine requires only one dose, not two. It also can remain stable in a refrigerator for months, whereas the others must be frozen to remain usable. That fact alone will massively simplify the logistics for local health departments, hospitals, pharmacies, and other providers as they struggle to get shots into arms. 

“You can get it and you’re done,” Dr. Marcus Plescia, the chief medical officer for the Association of State and Territorial Health Officials, told the New York Times. “Everybody is eager to have it out there. It has a lot of potential.”

If a large segment of the population can be protected by just one dose, it could make it harder for the virus to spread, helping bring the pandemic to heel. “A vaccine that is one dose would have a tremendous, tremendous public health impact,” Ruth Faden, a professor of biomedical ethics at Johns Hopkins University, told the Times.

How Effective Has the Johnson & Johnson Vaccine Been So Far in Clinical Trials?

According the results published in the New England Journal of Medicine, all participants in Johnson & Johnson’s phase 2 trials who received the vaccine developed antibodies to COVID-19, regardless of dosage. Possible side effects were also in line with the two vaccines already in use by Modern and Pfizer, including headache, muscle aches, and fatigue.

What Makes the Johnson & Johnson Vaccine Different from the Moderna and Pfizer Vaccines?

The Johnson & Johnson vaccine relies on a modified adenovirus—a type of virus that causes the common cold—to carry a gene from the coronavirus into the body’s cells, which then produce the coronavirus spike protein. This triggers the immune system itself to then fight off infection by the coronavirus. The adenovirus cannot replicate inside the cells or cause any illness. 

The Moderna and Pfizer vaccines, meanwhile, are mRNA (messenger RNA) vaccines, which essentially give the body the virus’ blueprint, causing the body’s cells to build a spike protein that triggers an immune response and builds up a defense against COVID-19. 

Why Do Scientists and Public Health Experts Feel Optimistic About This Vaccine?

Initial results of the company’s early-stage trials were promising, showing that a single dose prompted a strong antibody response. If the final data is similarly positive, the company will likely follow in Moderna and Pfizer’s footsteps and apply for an emergency use authorization with the US Food and Drug Administration.

Dr. Moncef Slaoui, who leads the Trump administration’s Operation Warp Speed vaccine effort, believes the company could receive approval for its vaccine sometime in February. 

“If submission is happening at the end of January, one could project that approval of the emergency use authorization may happen somewhere in the middle of February,” Slaoui said at a press conference on Tuesday. 

When Can the US Expect Large-Scale Availability of the Johnson & Johnson Vaccine?

While approval would be a positive step, it may take time to see the benefits of that, as the company has experienced unexpected delays in manufacturing the vaccine. In its $1 billion contract with the federal government, the company initially promised to have 12 million doses of its vaccine ready by the end of February and 100 million by the end of June. But as the New York Times reported, federal officials have been told the company is as much as two months behind and won’t catch up until the end of April. 

Given the speed with which the vaccine was developed, the delay wasn’t a surprise to some experts.

“This is really unfortunate, but also not surprising,” Dr. Angela Rasmussen, a virologist, wrote in a tweet. “It just goes to show that you can throw money at technically challenging problems but it doesn’t magically fix them, particularly when manufacturing a brand new vaccine at scale.”

Such a delay inevitably means it will take longer to vaccinate enough Americans to reach herd immunity, resulting in more deaths. 

Dr. Paul Stoffels, Johnson & Johnson’s chief scientific officer, said that assuming the FDA approves its vaccine, he hopes it will become available sometime in March. Slaoui said he expects the company to have in the “single-digit” millions of doses by the end of February before ramping up in March and April.