Johnson & Johnson's Covid-19 single-shot vaccine was shown to be 66% effective in preventing moderate and severe disease in a global Phase 3 trial, but 85% effective against severe disease, the company announced Friday.
The vaccine was 72% effective against moderate and severe disease in the US, the company said.
It's a striking difference from vaccines from Pfizer/BioNTech and Moderna, and it may give pause to people uncertain about which vaccine to get or when they can get one. The vaccines already on the market in the US are about 95% effective overall against symptomatic Covid-19, with perhaps even higher efficacy against severe cases.
But experts say the Johnson & Johnson vaccine will still be useful against the pandemic in the United States and around the world.
Dr. Anthony Fauci said on Friday the Johnson & Johnson vaccine and others will help alleviate stress on the US health care system.
"If we can alleviate that, that is really important -- not only with this candidate, but the others that have already gotten the EUA," Fauci, director of the National Institute of Allergy and Infectious Diseases, said during a call with reporters on Friday morning.
"If you can prevent severe disease in a high percentage of individuals, that will alleviate so much of the stress and human suffering and death."
The vaccine's efficacy against moderate and severe disease ranged from one country to another: 72% in the US, 66% in Latin America and 57% in South Africa. This was measured starting one month after the shot.
In South Africa, 95% of cases in the trial were due to a variant known as B.1.351, which is known to be more contagious and carries mutations that may make the virus less susceptible to the antibody immune response -- including antibodies prompted by vaccination.
With that variant, "we have a lower protection against milder forms of Covid than we did in the United States, where there were more typical circulating variants," Dr. Mathai Mammen, the company's global head of research and development, told CNN Chief Medical Correspondent, Dr. Sanjay Gupta.
However, even those who got moderate cases of Covid-19 in the trial tended to develop a milder course and fewer symptoms, he added.
But for Mammen, the key result was how effective the vaccine was at preventing severe disease -- regardless of variant or age group.
"Across all geographies, across all variants, we see 85% protection" against severe disease, he said. That trend increased over time, with no severe cases in the vaccinated group after day 49, according to the company.
From one month after the shot, all hospitalizations and deaths occurred in the placebo group.
The results are based on an analysis of more than 44,000 participants in eight countries, with 468 total cases of Covid-19 split between those receiving the vaccine or placebo. The results have not been published in a peer-reviewed journal, but the company said it plans to do so "in the coming weeks."
Johnson & Johnson is expected to apply to the US Food and Drug Administration next week for emergency use authorization, which Mammen said could come by late February.
It will be the third company to seek EUA from the FDA for a coronavirus vaccine. Vaccines made by Moderna and by Pfizer/BioNTech were authorized in December and are now being given to millions of Americans.
'Pretty good' for single-dose, affordable vaccine
Dr. Paul Offit, a vaccine expert at the University of Pennsylvania and a member of the FDA's Vaccines and Related Biological Products Advisory Committee, said that under normal circumstances, there might not be much of a market for a vaccine that is significantly less effective than two others already on the market. But he added that these are not normal times, with a pandemic raging and shortage of vaccines.
Pfizer and Moderna both use genetic technology called messenger RNA, or mRNA technology. Johnson & Johnson uses a weakened common cold virus, known as adenovirus, to carry genetic instructions into the body to prompt an immune response.
"In a better world, we would have abundant quantities of this messenger RNA vaccine, Pfizer and Moderna, and that would be damning for a vaccine that's clearly less effective. But that said, we have limited quantities of mRNA vaccine," Offit said.
Offit has been vaccinated, but said if he had not, he would first search out a Pfizer or Moderna vaccine, and then if he couldn't find one in reasonable period of time, he would take a Johnson & Johnson vaccine if it was available.Offit said getting one brand of vaccine and later on getting a different vaccine should not pose safety issues.
"I would make an effort to get an mRNA vaccine first," Offit said. "Not being able to get it, and knowing I might not be able to get Pfizer or Moderna for many months, and knowing this virus is still ranging across the country, I would take J&J in the secure knowledge that I could get Pfizer or Moderna later."
The Johnson & Johnson vaccine has advantages, Fauci said.
"A vaccine that's inexpensive, that's a single dose, and that has no cold chain requirements -- that's pretty good," Fauci told CNN.
Mammen said the vaccine was well-tolerated, with a "vanilla, even boring, safety data set" that included no cases of a severe allergic response known as anaphylaxis. About one in 11 had a fever, but only 0.2% were considered "Grade 3."
Fauci said the results would look even better if Janssen did not have to compete against the 94% and 95% efficacy seen in trials of the Pfizer and Moderna vaccines — even though the latter are calculated from overall symptomatic disease, while Johnson & Johnson's figures reference only moderate and severe cases.
"You know what the problem is? If this were out there and we didn't have the Moderna 94-95% .... We would have said wow, a 72% effective vaccine that's even more effective against severe disease is really terrific," he said in a telephone interview.
"But now we're always judging it against 94 to 95%. Having said that, this is a vaccine that could have use particularly in developing countries to keep people out of the hospital. It has a very good efficacy against severe disease," Fauci added.
Johnson & Johnson's Mammen pushed back against comparing its vaccine with those from Moderna and Pfizer.
"It's really hard to compare numbers head-to-head right now without running a study with two vaccines," he said.
Mammen said there were key differences between the trials; for example, Johnson & Johnson's vaccine was tested later, when cases were surging even higher in many parts of the world and new variants of coronavirus were already circulating. One in particular, called B.351, was dominant in South Africa when the vaccine was tested there. This variant has mutations that might be expected to weaken the vaccine's effects somewhat.
But it still protected people, Mammen said.
"I'm looking at that South African variant, and I'm seeing that we're able to completely protect against concerning levels of illness, where one might go to a hospital," he said.
Plus, people do not have to worry about coming back for a second dose.
"We really wanted it to be a single dose. So we optimized our antigen so that we get enough immunogenicity after one dose, as opposed to two," he said.
And, unlike the Pfizer and Moderna vaccines, it does not have to be stored in freezers. It can be stored for three months at refrigerator temperatures of 36 degrees to 46 degrees Fahrenheit.
Janssen is already testing a two-dose regimen of the vaccine and that could increase the efficacy, Fauci said.
"Let's see what that shows. It could possibly bring it up to 90%," he said. "Heck if you got 72 with a single dose, you would think you would do pretty good with a boost."
100 million dose US contract
The US federal government has contracted to buy 100 million doses of the vaccine, expected to be delivered by June.
Johnson & Johnson has said it's on track to produce a billion doses worldwide.
And the company has been manufacturing doses for months in anticipation that it would get emergency authorization from the FDA. The company hopes to begin shipping its product the day after it gets that authorization.
"We've been manufacturing at risk for a long time -- for more than nine months," Mammen said. "My expectation ... is, towards the end of February, we should have an emergency use authorization."
A fourth vaccine is also jostling to join the mix in the US market. Maryland-based Novavax released preliminary data Thursday showing its candidate vaccine had an efficacy of 89% in UK trials. And AstraZeneca is working to finish up Phase 3 clinical trials of its vaccine, as well.
The Johnson & Johnson vaccine is made differently from the Pfizer and Moderna vaccines, which use raw genetic material called messenger RNA. Johnson & Johnson's uses a common cold virus called adenovirus 26, which has been weakened so that it does not replicate in the body. It's engineered to carry genetic material from the spike protein of the virus -- that's the part the virus uses to grab onto the cells it targets.
The vaccine prompts the muscle cells in the arm to produce these pieces of spike protein. The immune system recognizes them as foreign and builds a defense, so when a real virus tries to infect cells, the body is ready to fight it off.