(CNN)The US public and even some health experts may have underestimated the Covid-19 vaccine made by Janssen, a division of Johnson & Johnson, new data shows. And there are indications that it could still play an important role in the future.
A study published Thursday in the medical journal JAMA Network Open found that the J&J vaccine remains durable and effective even through the spate of cases caused by the Delta variant. It was 76% effective overall in preventing Covid-19 infection and 81% effective in preventing Covid-related hospital admissions. The study also showed that it offered durable immunity for at least six months after the shots.
And a CNN analysis of information collected by the US Centers for Disease Control and Prevention showed that the J&J vaccine had the lowest breakthrough infection rate of any vaccine since the week ended December 25, the last five weeks of available data.
In January, during the Omicron surge, breakthrough infections were highest among those receiving the Pfizer/BioNTech vaccine, followed by those receiving Moderna. Those vaccinated with the Johnson & Johnson vaccine had the lowest incidence of breakthrough infections.
In the week ended January 22, there were 650 infections per 100,000 people with the J&J vaccine. Moderna had 757 per 100,000 and Pfizer 862 per 100,000.
Unvaccinated people were particularly vulnerable to getting sick during the Omicron and Delta waves, just like the original version of the coronavirus. They were 3.2 times more likely to get sick than people who had the J&J vaccine. The unvaccinated had a 2.8 times greater risk of infection than those receiving Moderna and 2.4 times greater risk than those receiving Pfizer.
“What we saw in the summer and fall during the delta rise is that all three vaccines were very, very protective. But the breakthrough rates in August, September last year with the Janssen vaccine were slightly higher than Pfizer and Moderna was slightly lower. But these differences were relatively small,” said Dr. Dan Barouch, director of the Center for Virology and Vaccine Research at Beth Israel Deaconess Medical Center in Boston. He helped develop and study the J&J vaccine.
“But what we’ve seen over time is that those differences then narrowed,” he said. “And in the first week of December we saw in the data that the lines were crossing,” with incidence rates for the J&J/Janssen vaccine becoming lower than the others.
“Reassuring” dates for J&J recipients
In March 2021, the J&J vaccine was the third to be approved by the U.S. Food and Drug Administration, and the initial response was more muted than the milestone approvals of Pfizer/BioNTech and Moderna’s mRNA vaccines.
The vaccines work differently. The mRNA vaccines essentially provide blueprints that train your body to fight that particular infection and any similar infection later on. Adenovirus vector vaccines, like J&J’s, use a virus that can behave like a Trojan horse. But instead of soldiers jumping out, the adenovirus releases genes that encode the coronavirus spike protein.
The J&J vaccine also stood out for other reasons: it came as a convenient single dose and didn’t require special refrigeration, while the mRNA vaccines required two doses and Pfizer’s required special cold storage. The flexibility was attractive to people who were afraid of gunshots or didn’t have the time to get two shots. It was also better for countries without a solid healthcare infrastructure.
But his performance dampened some of the enthusiasm, especially from the public.
While the mRNA vaccines were hailed for their “amazing” effectiveness of more than 90%, some were stunned by the news that J&J was 65% effective in preventing symptomatic Covid-19 in volunteers in clinical trials.
From the beginning, the supply of J&J vaccines was more limited. After the vaccine was approved, the federal government briefly paused its use due to safety concerns related to rare blood clotting events. Even after vaccinations resumed, the pace of J&J vaccinations never recovered.
In December, the CDC revised its recommendations to favor Moderna and Pfizer/BioNTech shots over J&J. It also urges people who got the J&J vaccine to get a booster shot of one of the mRNA vaccines two months later.
The protection provided by the Covid-19 vaccines has diminished over time, and none of them work as well against the variants that have emerged since the original coronavirus emerged. But science is starting to show that people who received the J&J Covid-19 vaccine may have an advantage.
Barouch told CNN he was “not at all surprised” to see that the shelf life of Johnson & Johnson’s vaccine appears to last longer than that of mRNA vaccines — Pfizer/BioNTech and Moderna — based on the frequency of breakthrough infections.
mRNA vaccine technology has been shown to elicit a strong and robust immune response rapidly after vaccination, but this may decline over time. Johnson & Johnson’s virus vector platform may not elicit such a strong immune response in the short term, but is known for its strong durability.
“Over time, the effectiveness of the Pfizer and Moderna vaccines decreases, the effectiveness of the J&J vaccines remains stable, and so it is exactly as you predicted: they will converge and then intersect,” Barouch said .
The J&J vaccine could also have “a particular benefit,” he said.
“The immune system actually consists of two arms: the antibody side and the T cells. And the type of T cells that are critical to preventing serious disease are called CD8 T cells,” Barouch said. “The J&J vaccine produces better CD8 T cells than the Pfizer and other mRNA vaccines, so the J&J vaccine could have a particular advantage for variants like Omicron that have largely escaped antibody responses.”
Overall, Barouch called these data “very reassuring” for recipients of the J&J vaccine.
“They should be confident that they have received a vaccine that offers very good protection over a long period of time,” Barouch said. “And I think the second message is that I think people should also learn about this new data when it comes to considering booster shots.”
Perspectives as a booster?
David Montefiori, a virologist at Duke University Medical Center, said, “The J&J vaccine has gotten a bad rap for its effectiveness, but the stability of the response is intriguing.”
Antibody levels fell with each vaccine during the Omicron surge, and that could mean people need an extra boost. More research is needed to find out.
A yet-to-be-published National Institutes of Health study looking at a mix-and-match vaccine strategy showed good results when J&J was included, Montefiori said.
“In people who received the Pfizer vaccine first and then a booster with the J&J vaccine, these people developed fairly high levels of neutralizing antibodies against Omicron: 10 times higher than people who received two shots with just the J&J vaccine “, he said. “So the J&J vaccine could be a good boost for people who initially received an mRNA vaccine.”
The Johnson & Johnson vaccine can be used for primary doses or as a booster dose, but the CDC says the Pfizer and Moderna vaccines are recommended in most situations because of the risk of serious adverse events with the Johnson & Johnson vaccine.
The J&J vaccine has been associated with rare cases of blood clots with low platelets known as thrombosis with thrombocytopenic syndrome or TTS. “It occurs at a rate of approximately 3.83 cases per million Janssen doses and has resulted in fatalities,” says the CDC.
dr Angela Branche, an infectious disease specialist and associate professor of medicine at the University of Rochester, said the side-effect profile of the J&J vaccine “remains something of concern for some groups where this risk is high.” According to the CDC, women ages 30 to 49 are at increased risk for this rare side effect.
But if that research is successful, the J&J vaccine could only be useful for certain populations as a booster shot.
“For some groups who aren’t at very high risk of developing serious blood clots, like older adults, this can be a good strategy,” Branche said.
Montefiori said the vaccine deserved more studies.
“I think there may still be a place for the J&J vaccine in the long-term picture of this pandemic,” Montefiori said.
CNN’s Jacqueline Howard and Tasnim Ahmed contributed to this report.
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