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Johnson & Johnson Krem do Twarzy - Odkryj Tajemnice Zdrowej i Promiennej Skóry
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."
What are the side effects?
The most common side effects reported in Johnson & Johnson's clinical trials are generally expected after any vaccination. They include pain at the injection site, redness of the skin, muscle pain, headache, fatigue, nausea and fever. While they may be uncomfortable, they actually signal that the immune system is responding to the vaccine.
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No serious or long-term side effects were reported during Johnson & Johnson's clinical trials, but the company is investigating two cases of severe allergic reactions that were reported later. Health care providers are advised to monitor people who have histories of allergic reactions for 30 minutes after vaccination and all other patients for 15 minutes.
According to the Centers for Disease Control and Prevention, rare cases of anaphylaxis, a life-threatening allergic reaction, occurred at a rate of 4.5 cases per 1 million doses administered of both the Moderna and the Pfizer-BioNTech vaccines.
Entering a Cell
After the vaccine is injected into a person’s arm, the adenoviruses bump into cells and latch onto proteins on their surface. The cell engulfs the virus in a bubble and pulls it inside. Once inside, the adenovirus escapes from the bubble and travels to the nucleus, the chamber where the cell’s DNA is stored.
Building Spike Proteins
The mRNA leaves the nucleus, and the cell’s molecules read its sequence and begin assembling spike proteins.
Some of the spike proteins produced by the cell form spikes that migrate to its surface and stick out their tips. The vaccinated cells also break up some of the proteins into fragments, which they present on their surface. These protruding spikes and spike protein fragments can then be recognized by the immune system.
The adenovirus also provokes the immune system by switching on the cell’s alarm systems. The cell sends out warning signals to activate immune cells nearby. By raising this alarm, the Johnson & Johnson vaccine causes the immune system to react more strongly to the spike proteins.
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.
