What we know about Covid-19 vaccines and their side effects

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Paris (AFP)

The distribution of the first coronavirus vaccines raised hopes that the end of the pandemic could be in sight, but it also raised concerns about side effects.

Here’s what we know so far.

– What side effects? –

End-phase clinical trial results for two of the flagship vaccines were released this week and both are considered safe.

Data on the Pfizer / BioNTech vaccine – already licensed in several countries – has been published in the peer-reviewed scientific journal New England Journal of Medicine.

The drug is based on an experimental technology that uses a synthetic version of a molecule called “messenger RNA” to hack human cells and effectively turn them into vaccine factories.

His trial involved 40,000 volunteers and suggested that the vaccine causes only mild side effects.

About 80% of people vaccinated experienced pain at the injection site. Many also experienced fatigue, headaches, and muscle aches, and some had temporarily swollen lymph nodes.

These side effects were more common and more intense in young people.

A partnership between the University of Oxford and AstraZeneca uses a deactivated virus – in this case a chimpanzee adenovirus – as a vehicle to transport the vaccine.

Their vaccine data – from trials involving some 23,000 volunteers – have been published in another prestigious medical journal, The Lancet. The study found the vaccine to be safe.

– Pick and mix? –

Saying that you prefer one vaccine to another is like saying that you prefer chocolate ice cream to strawberry ice cream, according to the virologist of the National Institute for Health Research (INSERM) Marie-Paule Kieny.

She told citizens of the French parliament should be aware that vaccines could “injure the arm and cause fatigue,” comparing the side effects to those that children experience when they receive a stroke.

“It’s unpleasant, for a day or two maybe, but these reactions are short lived and if combined with a high level of protection, I think it should be tolerable. ”

– Rare events –

Serious side effects from both vaccines have so far been extremely rare.

A single patient who received the Oxford AstraZeneca vaccine had a “possibly serious side effect” from the injection, according to data from The Lancet.

The patient suffered from transverse myelitis, a rare neurological disease that causes inflammation of the spinal cord.

This caused the temporary global halt to the trials in early September.

Two other serious side effects were observed, although these were not attributed to the sting.

Researchers said all three have recovered.

Four cases of Bell’s palsy – an often temporary facial palsy – were seen in 18,000 volunteers for two months in the Pfizer / BioNTech trial.

But the frequency is similar to that normally seen in the general population for this condition, so it is not clear whether the cases were caused by the vaccine.

To be on the safe side, the United States Food and Drug Administration (FDA) has recommended special caution.

There were eight cases of appendicitis in those who received the vaccine, double the amount for those who received the placebo.

But the FDA attributed this to a statistical coincidence, unrelated to the vaccine.

As with any drug, the hypothesis of serious side effects cannot be excluded. A substance is evaluated by weighing the benefits against the risks.

“It is quite acceptable to have a vaccine that is slightly more reactogenic, if its side effects are not severe,” said Isabelle Parent, vaccine expert at the French Medical Agency (ANSM).

– What about allergies? –

After Britain started administering the Pfizer / BioNTech vaccine earlier this week, British health officials said two patients suffered side effects.

Both are said to have serious allergic pathogens, as they always carry adrenaline on them.

In response, UK authorities have warned anyone with “a history of a significant allergic reaction to a vaccine, drug or food” to avoid taking the vaccine.

“For the general population, that doesn’t mean they should be anxious to receive the vaccination,” said Stephen Evans, professor of pharmacoepidemiology at the London School of Hygiene and Tropical Medicine, at the Science Media Center (SMC).

“You have to remember that even things like the cooking pot can cause unexpected serious allergic reactions,” he added.

Those responsible for the clinical trial anticipated the risk, excluding volunteers with a history of severe allergic reactions to vaccines in general or to any component of the vaccine.

Millions of people who suffer from allergies to common substances such as eggs and nuts do not appear to be allergic to the vaccine.

“It will be important now to understand the specific nature of the reactions and the medical history of those affected,” said Graham Ogg, acting director of the Human Immunology Unit of the Oxford Medical Research Council at SMC.

– Long-term –

Since the vaccines are new, scientists are uncertain about the potential long-term side effects.

While they may be cleared for emergency use due to the pandemic, their data will be continuously monitored by global health authorities so they can respond immediately.

“As is normal with any vaccine, close and continuous monitoring of safety and efficacy data as it is delivered will be essential,” said Dr. Charlie Webber, vaccine manager for the organization. Wellcome charity, according to SMC.

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