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Johnson & Johnson Krem do Twarzy - Odkryj Tajemnice Zdrowej i Promiennej Skóry
What's in the vaccine?
After the Johnson & Johnson vaccine was granted emergency use authorization by the FDA, concerns arose about what's in it and how it was made.
The Johnson & Johnson vaccine doesn't contain fetal tissue, but like many other vaccines, it was tested and developed using cells that were derived from fetal tissue decades ago. The cells are commonly used in scientific research because they can replicate easily, which means scientists in effect have an unlimited supply of these "immortalized" cell lines.
"You can grow them very quickly and then they just divide and divide and divide," Kriegstein said.
In vaccine research, human fetal cell lines are used to assess how well the candidates perform. The cells were instrumental, for instance, in the development of vaccines that protect against chickenpox, rubella and polio, Kriegstein said.
"If you're trying to test a vaccine to see if it works effectively and you need to create large numbers of the virus, the quickest way is to grow them in these human cells," he said. "They're perfect hosts for the virus."
Indeed, Johnson & Johnson used cells derived from fetal tissue to grow the adenoviruses needed to manufacture the vaccine. But the cells aren't an ingredient in the vaccines themselves.
"The cells that are used now were never in a fetus — they are not fetal cells," Kriegstein said. "In fact, these cell lines have been used for decades, and they have divided and divided tens of thousands of times, so we're not talking about any cells that actually came directly from a fetus."
How does the Johnson & Johnson vaccine compare to other vaccines?
At first glance, the Johnson & Johnson vaccine looks to be the inferior option compared to the vaccines from Pfizer-BioNTech and Moderna, both of which reported around 95 percent effectiveness in their Phase 3 clinical trials.
Experts say that in no way should those percentages be interpreted in a way that suggests that the Johnson & Johnson shot — with its 72 percent effectiveness — is 23 percentage points less effective.
The percentages can't be compared directly to one another, because the trials were run differently. The vaccines were studied at different times during the pandemic, when different variants were circulating.
SARS-CoV-2, the virus that causes Covid-19, has been changing ever since it was discovered in Wuhan, China.
"The virus that swept through China was not the virus that left China," Offit said. "The virus that left China was the first variant, and it was more contagious than the one that originally popped up."
That could account for the decreased effectiveness reported in Johnson & Johnson's trials — there's no way to know how the Moderna and the Pfizer-BioNTech vaccines would have fared in the same scenario.
"I am speculating," said Dr. William Schaffner, an infectious diseases expert at Vanderbilt University Medical Center, "but the notion is that, yes, we think that if the Moderna and Pfizer people had been in South Africa at the same time that Johnson & Johnson were testing their vaccine, we would probably get all very comparable results."
How Effective Is It?
Johnson & Johnson announced that its single-dose vaccine was 66% percent effective at preventing moderate to severe disease from COVID-19 and 85% effective at preventing severe disease. This effectiveness in the Phase 3 trial was reached 28 days after vaccination.
The trial had a temporary delay in October 2020 when it was paused due to a patient reporting an unexplained illness, although no specific details were provided about what happened due to patient privacy. Regulators determined that the event was not related to the vaccine and the trial was safe to resume.
The efficacy against moderate to severe COVID-19 infection varied by region in the trial. It was 72% in the United States, 68% in Latin America, and 64% in South Africa.
The vaccine was also found to be fully protective against hospitalization and death, and the protection against severe disease included multiple variants of COVID-19, including the B.1.351 variant found in South Africa.
Effectiveness Against COVID-19 Variants
According to information released by Johnson & Johnson, the vaccine was found be 85% effective against severe/critical disease from COVID-19, including that caused by the Delta variant. Data from a clinical study published in The New England Journal of Medicine also supported this finding.
In December 2021, the Centers for Disease Control and Prevention (CDC) endorsed updated recommendations made by the Advisory Committee on Immunization Practices (ACIP), “expressing a clinical preference for individuals to receive an mRNA COVID-19 vaccine over Johnson & Johnson’s COVID-19 vaccine.”
There is currently limited data available showing how effective the vaccine is at protecting against the Omicron variant. One study published in June 2022 found two doses of the vaccine to be 72% effective against hospitalization, 1 to 2 months after receiving the second dose. However, in their request to the FDA to revoke their EUA, Janssen stated they did not intend to update the vaccine to target emerging variants.