What you need to know about the J&J vaccine

What you need to know about the J&J vaccine
WASHINGTON: Johnson & Johnson's single dose of Covid-19 injection is expected to be approved Thursday by the European Union, the block's fourth vaccine in the fight to end the pandemic chapter.
Here's What You Should Know.
Perhaps the most important figure to watch out for is "zero".
That's the number of people who died of Covid-19 after receiving the injection in a large-scale global study involving 40,000 people, compared to seven who received the placebo.
Overall, the vaccine prevented moderate to severe Covid-19 by 66.1 percent 28 days after the injection, but this increased to 85.4 percent when only serious illness was considered.
Most notably, the good results against serious diseases were sustained in both South Africa and Brazil, where respective variants were dominant during the trial period.
Regarding safety, an analysis of 44,000 people showed that it was generally well tolerated, with typical side effects such as injection site pain, headache, fatigue and muscle aches.
At least one case of anaphylaxis (severe allergic reaction) has been reported – and in rare cases such reactions have also been recorded with other Covid-19 vaccines.
Documents shared by the U.S. Food and Drug Administration, which has already approved the emergency, showed a handful of cases where people taking the vaccine developed hives.
The FDA also said that long-term monitoring was needed to determine if the vaccine was associated with a small number of cases of potentially dangerous clotting and tinnitus.
The RNA-based vaccines from Pfizer and Moderna have been found to have approximately 95 percent efficacy against all forms of Covid-19 – but it is still difficult to make a direct comparison.
That's because their clinical trials took place before newer variants, some of which have been shown to be less susceptible to current vaccines, were well established.
The RNA vaccines probably still have a head start, but the J&J vaccine brings important logistical advantages.
It only requires one shot and can be kept in refrigerators for a long time instead of freezers – especially important for developing countries.
Although one case of anaphylaxis has been reported, it is suspected that it will cause fewer such reactions due to the way the vaccine is formulated.
The J&J vaccine uses a cold-causing adenovirus, which has been genetically modified so that it cannot replicate, to carry the gene for an important part of the coronavirus.
The part is known as the "spike protein" and it is what gives the virus its crown-like appearance.
The vaccine instructs human cells to make this protein, and our immune system then develops antibodies against it, preventing the virus from entering the cells.
In addition to antibodies, the vaccine also induces the production of immune T cells, which kill infected cells and help make more antibodies.
J & J's injection is known as an "adenovirus vector vaccine," and the company previously produced a European Union-approved Ebola vaccine using the same technology.
The Oxford-AstraZeneca and Sputnik shots are also both adenovirus vector vaccines.
They all use double-stranded DNA molecules to carry genetic instructions, rather than single-stranded RNA used by Pfizer and Moderna.
The DNA is more robust, allowing these vaccines to be stored at higher temperatures.
J&J, meanwhile, is moving forward with clinical tests for children and pregnant women.
While the J&J vaccine has been a single dose until now, the company is also testing a two-dose regimen to see if it elicits a better response.
But RNA vaccines may have an edge over adenovirus vaccines when it comes to boosters.
Some scientists have expressed concern that the immune system will recognize and attack adenoviruses it has encountered before, which in turn reduces the effectiveness of the second shot.
This may become especially important as makers seek to develop variant-specific vaccines, as makers of adenovirus vaccines may need to find new vectors.

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