What you need to know about Johnson & Johnson vaccine / Adverse effects and why the booster is being studied

Johnson & Johnson’s anti-Covid vaccine is being investigated by the European Medicines Agency for blood clots. What you need to know about this American vaccine, according to AFP.

– How effective?

Its effectiveness has been tested in clinical trials in approximately 40,000 people aged 18 years or older in several countries, including the United States, Mexico, Brazil, and South Africa. About half received the vaccine, the other half received a placebo, and the two groups were compared.

The vaccine has been shown to be 85% effective in preventing severe forms of Covid-19, which is crucial as it prevents hospitalizations and deaths. No vaccinated people died from Covid-19 during the studies, compared with seven deaths in the placebo group.

The vaccine was also 66% effective in preventing moderate to severe forms of the disease. A rate that brings together different realities between countries: from 72% in the United States to 64% in South Africa, where a variant (B.1.351) was already the majority at the time of the clinical study, according to data analyzed by the US Medicines Agency.

What about other vaccines? The 66% result cannot be fully compared to the approximately 95% efficacy displayed by Pfizer and Moderna vaccines, experts warn. Indeed, clinical trials of the last two were performed when variants, especially the South African variant, were not yet widespread.

– Convenient-

The vaccine has several logistical advantages. It requires a single injection, unlike vaccines from Pfizer / BioNTech, Moderna or AstraZeneca, which are given in two divided doses every few weeks.

In addition, it can be stored for 3 months at the standard temperature of the refrigerator, making it easy to distribute.

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– What side effects?

The most common side effects seen in clinical trials were injection site pain, headache, fatigue, and muscle aches.

The American laboratory reported at the end of February at least one case of anaphylaxis – a serious allergic reaction – in South Africa.

Such reactions, although very rare, were also caused by injections of Moderna and Pfizer vaccines.

In the United States, the Centers for Disease Control and Prevention (CDC), the country’s leading federal public health agency, advises people who have already had severe allergic reactions not to get the vaccine.

On Friday, the European Medicines Agency said its safety committee had “launched a study” aimed at “evaluating thromboembolic incident information” on people who received the vaccine from the Johnson & Johnson laboratory.

– What technology?

Johnson & Johnson vaccine is a “viral vector” vaccine.

Use another low virulent virus as a carrier, transformed to add genetic instructions from a part of the virus responsible for Covid-19. Once in the cells, a typical SARS-CoV-2 protein is produced, educating the immune system to recognize it.

– Additional tests-

The pharmaceutical company announced that it is studying the effect of two doses, instead of one, on immune protection.

Some scientists have expressed reservations about the effect of this additional dose, thanks to the technique used for this vaccine: the immune system could recognize the weakly virulent “vehicle” virus injected a second time and eliminate it immediately.

“J&J” also began studies in adolescents between the ages of 12 and 17.


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