An unapproved Johnson & Johnson vaccine is highly effective at preventing severe COVID-19 cases, the company and top government scientists announced Friday, lifting hopes that more vaccines could soon be on the way.

The vaccine was found to be 66 percent effective at preventing moderate and severe cases in a randomized placebo-controlled clinical trial of 45,000 participants, and 72 percent effective among U.S. participants. The vaccine was shown to be 85 percent effective at preventing severe cases. No COVID-19 deaths occurred among people who received the vaccine, while five people who received the placebo died of COVID-19.  

“If this had occurred in the absence of a prior announcement and implementation of vaccines that are 95 and 94 effective, you would say, ‘This is an absolutely spectacular result.’ And in fact it is extraordinarily important,” said National Institutes of Health senior official Anthony Fauci.

The company is expected to file an application for an emergency use authorization from the Food and Drug Administration within days. If the FDA is satisfied with the data, the vaccine could help smooth out bottlenecks in the labored vaccine rollout across the U.S. 

Unlike two previously authorized vaccines by Pfizer-BioNTech and Moderna, which are at least 95 percent and 94 percent effective, respectively, but require two doses, the Johnson & Johnson product only requires one shot to achieve immunity and can be stored for months at refrigerator temperatures rather than the colder requirements of the other vaccines.

Fauci underscored the new vaccine’s 85 percent efficacy against severe cases even in South Africa where a different variant is prevalent. The vaccine was found to be effective but less so in South Africa. Efficacy differed across different geographies: 72 percent in the United States; 66 percent in Latin American countries and 57 percent in South Africa.

Fauci said the decline in efficacy in South Africa underscores the looming challenge of containing variants of the virus. The South African variant, which does not seem to cause more severe disease but is more transmissible, was discovered recently in the United States.

“This virus will continue to mutate,” Fauci said. “The best way to prevent further mutation of a virus is to prevent its replication, and you do that by vaccinating as many people as you can.”

Need for vaccine supply

Two million doses are ready to ship as soon as regulators greenlight the vaccine, according to a new government report. The company originally planned to ship 12 million doses by the end of February. But manufacturing problems could delay the delivery schedule, The New York Times reported earlier this month. 

In August, the Trump administration agreed to pay $1 billion for 100 million doses of the vaccine if it is approved. The company expects to produce 100 million doses by July. 

Experts hope the approval of the Johnson & Johnson vaccine could help relieve supply shortages across the country. 

A trickle of supply has stunted plans to ramp up to more locations, including massive stadiums, in recent weeks. Governors have opened up eligibility to millions more people than can be vaccinated with the current supply, in part because of statements by Trump administration leaders that state officials call misleading. Essential workers and seniors have been forced to jostle for priority.

With more transmissible variants from South Africa and the United Kingdom now within the U.S., public health officials are anxious to vaccinate the population as quickly as possible.

The one-shot regimen made the clinical trial speedier than if Johnson & Johnson had tested a two-dose vaccine, but the approach may have also made the vaccine less efficacious, according to some analysts. Johnson & Johnson announced in the fall that it had a backup plan: a second phase 3 trial to observe the effects of two doses. The results of that separate trial are not expected until later this year. 

The Pfizer-BioNTech vaccine showed 95 percent efficacy at preventing illness in a trial of 44,000 volunteers. The Moderna vaccine showed 94.1 percent efficacy in a 30,000-person trial. Data on protection against severe cases is more limited, but both vaccines indicated high efficacy there, too: Nine of the 10 severe cases in the Pfizer trial occurred in people in the placebo group, and no severe cases occurred in the vaccine arm of the Moderna trial.

The Johnson & Johnson vaccine uses double-stranded DNA to store the virus’ genetic instructions for building the spike protein, which works to fight infection. This approach differs from the Pfizer and Moderna vaccines, which store the genetic instructions to build a spike protein in single-stranded RNA.

Johnson & Johnson’s vaccine packages DNA in a gutted adenovirus, a type of virus that causes the common cold, to stop COVID-19’s spread. The harmless adenovirus carries a coronavirus gene into human cells, so it produces the COVID-19 spike protein — but not the coronavirus itself. The spike protein gears up the immune system so that it can fight off the infection by the coronavirus.

The vaccine presents the body with part of the coronavirus, but not all of it, so the vaccine won’t infect you. The vaccine can be likened to getting part of a car but not essential components like the engine, so the car won’t be able to drive.

The gutted adenovirus vaccine is more stable than the mRNA vaccines. While the mRNA vaccines must be stored at ultra-cold temperatures, the Johnson & Johnson vaccine can remain stable for three months at the temperature of a standard home refrigerator, 35 to 46 degrees Fahrenheit.  

Johnson & Johnson took this same approach and used an adenovirus when it made its Ebola vaccine and investigation vaccines for HIV. 

Experts have confidence in the safety of viral vector vaccines. But they have a drawback in that some may have a pre-existing immunity to the adenovirus that packages the coronavirus DNA.

In March, Johnson & Johnson received $604.6 million in research and development funding from the U.S. government. In November, the company received another $454 million in public funds for research and development. 

The next steps are the submission of the emergency use authorization application by the company, and a public hearing of the FDA’s independent vaccine experts.