J&J Single-Dose Covid-19 Vaccine Gains Backing From FDA Advisory Panel

The panel, a group of 22 medical specialists in such fields as internal medicine, pediatrics, vaccines and epidemiology, regularly advises the FDA about experimental vaccines. It voted to recommend shots from Pfizer Inc. PFE -0.98% and partner BioNTech BNTX -2.94% SE and Moderna Inc. MRNA 4.33% before the agency authorized those two-dose vaccines in December.

The vaccine’s effectiveness and safety results were “way over the bar,” said panel member Eric Rubin, who is editor in chief of the New England Journal of Medicine. “The demand is so large that this vaccine clearly has a place.”

Arnold Monto, the panel’s acting chairman and a professor of public health and epidemiology at the University Michigan, said people should welcome getting J&J’s shot if it is authorized. “In this environment, whatever you can get, get,” he said.

During the all-day public meeting, representatives from the FDA and J&J discussed the safety and effectiveness of the company’s vaccine in a 44,000-plus subject study, as well as how effective the J&J vaccine is in preventing new cases caused by variants.

The give-and-take of questions and answers can be valuable in bolstering public confidence in the shot, according to FDA officials.

The vaccine was 66% effective at protecting people from moderate to severe Covid-19, an FDA review found, and even more effective at preventing severe disease alone.

“If authorized, Janssen’s vaccine candidate would play a pivotal role in the global effort to fight Covid-19,” Johan Van Hoof, global head of vaccines research at J&J’s Janssen pharmaceutical unit, said during the panel’s meeting. “A single-dose regimen offers the ability to vaccinate a population faster.”

A rollout of the J&J vaccine could add enough shots in the U.S. by the end of March to boost the total number of people vaccinated by 20%. Health authorities are pushing to inoculate enough people as quickly as possible so that business, schools and other establishments can fully reopen.

J&J has said it would deliver about 20 million doses for U.S. use by the end of March.

The FDA often convenes public meetings of outside experts to scrutinize experimental drugs, devices and vaccines up for agency approval, in part to boost public acceptance of the products should they be cleared for wide use.

J&J’s vaccine appeared to be safe in its pivotal study, the FDA found, aside from being effective.

“The known and potential benefits of Ad26 outweigh the known and potential risks,” Macaya Douoguih, head of clinical development and medical affairs at J&J’s Janssen unit, said during Friday’s meeting, using a code name for J&J’s vaccine.

FDA medical officer Yosefa Hefter said there are still unknowns about the vaccine, including duration of immune protection and the safety and effectiveness in use with children.

Vaccines’ Effectiveness

Number of doses

Overall efficacy

Efficacy against

severe disease

Efficacy in people

65 and older

Efficacy in U.S.

An FDA analysis for the committee meeting also said rare cases of deep vein clots and of blockages in lung arteries were slightly more common in vaccine recipients than in placebo patients, and that the FDA considers these to be “of clinical interest.”

The vaccine was effective “across demographic subgroups,” the FDA said. The demographic subgroups in the large study of J&J’s shot included racial and ethnic groups such as Black, Latino and Asian people, and age groups such as those 60 years and older.

Researchers also assessed efficacy in people who had underlying medical conditions including obesity and high blood pressure before entering the clinical trial. Sometimes vaccines don’t work as well in older people because of weakened immune systems. The J&J vaccine appeared to be less effective in people 60 and older who had certain medical conditions like diabetes and high blood pressure.

The Pfizer-BioNTech and Moderna vaccines also worked effectively across various demographic subgroups.

The J&J vaccine was less effective in South Africa than in the U.S. J&J is among the companies working on new shots targeting a more-transmissible Covid-19 variant that has thrived in South Africa and against which several current vaccines don’t appear to work as well.

J&J’s shot, however, was very effective against severe and critical cases in South Africa. The vaccine was 73.1% effective in preventing such cases occurring at least 14 days after vaccination, and 81.7% effective in preventing such cases at least 28 days after vaccination.

How Viral Vector Vaccines Work

Johnson & Johnson’s vaccine relies on a different mechanism for conferring immunity than traditional vaccines.

Traditional Vaccines

1. In classic vaccines, such as those against measles and polio, the patient is inoculated with weakened or inactivated versions of the virus. This triggers the immune system to produce specialized antibodies that are adapted to recognize the virus.

2. After vaccination, the antibodies remain in the body. If the patient later becomes infected with the actual virus, the antibodies can identify and help neutralize it.

Weakened virus vaccine

Actual viral infection

antibodies

Johnson & Johnson’s Vaccine

Scientists have isolated the genes in coronavirus responsible for producing these spike proteins. The genes are spliced into weakened, harmless versions of other viruses.

Instead of using the whole virus to generate an immune response, these vaccines use only coronavirus’s outer spike proteins, which are what antibodies use to recognize the virus.

Weakened virus with

spike protein genes

Spike

proteins

When injected into a patient, the genetically engineered viruses enter healthy cells where they produce coronavirus spike proteins.

The spike proteins produced by the cells prompt the immune system to mount a defense, just as with traditional vaccines.

Spike protein

Vaccine-generated antibody response

1. In classic vaccines, such as those against measles and polio, the patient is inoculated with weakened or inactivated versions of the virus. This triggers the immune system to produce specialized antibodies that are adapted to recognize the virus.

2. After vaccination, the antibodies remain in the body. If the patient later becomes infected with the actual virus, the antibodies can identify and help neutralize it.

Weakened virus vaccine

Actual viral infection

antibodies

Johnson & Johnson’s Vaccine

Scientists have isolated the genes in coronavirus responsible for producing these spike proteins. The genes are spliced into weakened, harmless versions of other viruses.

Instead of using the whole virus to generate an immune response, these vaccines use only coronavirus’s outer spike proteins, which are what antibodies use to recognize the virus.

Weakened virus with

spike protein genes

Spike

proteins

When injected into a patient, the genetically engineered viruses enter healthy cells where they produce coronavirus spike proteins.

The spike proteins produced by the cells prompt the immune system to mount a defense, just as with traditional vaccines.

Spike protein

Vaccine-generated antibody response

1. In classic vaccines, such as those against measles and polio, the patient is inoculated with weakened or inactivated versions of the virus. This triggers the immune system to produce specialized antibodies that are adapted to recognize the virus.

2. After vaccination, the antibodies remain in the body. If the patient later becomes infected with the actual virus, the antibodies can identify and help neutralize it.

Weakened virus vaccine

Actual viral infection

antibodies

Johnson & Johnson’s Vaccine

Scientists have isolated the genes in coronavirus responsible for producing these spike proteins. The genes are spliced into weakened, harmless versions of other viruses.

Instead of using the whole virus to generate an immune response, these vaccines use only coronavirus’s outer spike proteins, which are what antibodies use to recognize the virus.

Weakened virus with

spike protein genes

Spike

proteins

When injected into a patient, the genetically engineered viruses enter healthy cells where they produce coronavirus spike proteins.

The spike proteins produced by the cells prompt the immune system to mount a defense, just as with traditional vaccines.

Spike protein

Vaccine-generated antibody response

1. In classic vaccines, such as those against measles and polio, the patient is inoculated with weakened or inactivated versions of the virus. This triggers the immune system to produce specialized antibodies that are adapted to recognize the virus.

Weakened virus vaccine

antibodies

Actual viral infection

2. After vaccination, the antibodies remain in the body. If the patient later becomes infected with the actual virus, the antibodies can identify and help neutralize it.

Johnson & Johnson’s Vaccine

Instead of using the whole virus to generate an immune response, these vaccines use only coronavirus’s outer spike proteins, which are what antibodies use to recognize the virus.

Spike proteins

Scientists have isolated the genes in coronavirus responsible for producing these

spike proteins. The genes are spliced into weakened, harmless versions of other viruses.

Weakened virus with

spike protein genes

When injected into a patient, the genetically engineered viruses enter healthy cells where they produce coronavirus spike proteins.

Spike protein

The spike proteins produced by the cells prompt the immune system to mount a defense, just as with traditional vaccines.

Vaccine-generated antibody response

J&J, citing preliminary evidence in an analysis released by the FDA, said the vaccine was 65.5% effective in preventing asymptomatic infections in a subset of study subjects.

Health authorities have been watching whether Covid-19 shots can stop people without symptoms from transmitting the virus. The virus has largely been spread by people who were infected but didn’t realize it because they had no symptoms.

Write to Thomas M. Burton at [email protected] and Peter Loftus at [email protected]