The distribution of the first vaccines for the coronavirus
It has raised hopes that the end of the pandemic is in sight, but it has also raised some concern about the side effects.
This is what we know so far.
What side effects?
Results from end-stage clinical trials of two of the pioneering vaccines were released this week, and both are considered safe.
Data from the Pfizer / BioNTech vaccine, already licensed in several countries, was published in the peer-reviewed New England Journal of Medicine.
The drug is based on experimental technology that uses a synthetic version of a molecule called “messenger RNA” to hack human cells and effectively turn them into vaccine manufacturing factories.
His trial involved 40,000 volunteers and suggested that the vaccine causes only mild side effects.
About 80 percent of those vaccinated experienced pain at the injection site. Many also experienced fatigue, headache, and muscle pain, and some had temporarily swollen lymph nodes.
These side effects were more frequent and intense for young people.
A partnership between the University of Oxford and AstraZeneca uses a disabled virus, in this case a chimpanzee adenovirus, as a vehicle to transport the vaccine.
Their vaccine data, from trials involving some 23,000 volunteers, were published in another prestigious medical journal, The Lancet. The study found the vaccine to be safe.
Pick and mix?
Saying you prefer one vaccine to another is like saying you prefer chocolate ice cream to strawberry ice cream, according to Marie-Paule Kieny, a virologist at the French National Institute for Health Research (INSERM).
He said citizens of the French parliament should be aware that vaccines could “damage the arm and induce fatigue”, comparing the side effects with those experienced by children when they receive an injection.
“It’s unpleasant, maybe for a day or two, but these reactions are short-lived and if they are associated with a high level of protection, I think it should be tolerable.”
Rare events
Until now, serious side effects from both vaccines have been extremely rare.
Only one patient who received the Oxford AstraZeneca injection had a “serious possibly related 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 led to the temporary global closure of the trials in early September.
Two other serious side effects were noted, although they have not been attributed to the puncture.
Investigators said all three had recovered.
Four cases of Bell’s palsy, a facial paralysis that is often temporary, were seen among 18,000 volunteers over two months in the Pfizer / BioNTech trial.
But the frequency is similar to what is normally seen in the general population for this condition, so it is not clear if the cases were caused by the vaccine.
To be safe, the United States Food and Drug Administration (FDA) recommended special precaution.
There were eight cases of appendicitis in those who received the vaccine, twice as many as those who received the placebo.
But the FDA attributed this to a statistical coincidence, not related to the vaccine.
As with all medicines, the hypothesis of serious side effects cannot be ruled out. A substance is evaluated by weighing the benefits against the risks.
“It is completely acceptable to have a vaccine that is a little more reactogenic, if its side effects are not serious,” said the vaccine expert from the French agency for medicine (ANSM) Isabelle Parent.
What about allergies?
After Britain began administering the Pfizer / BioNTech vaccine earlier this week, British health authorities said two patients had suffered adverse reactions.
Both were said to have serious allergic pathogens, to the extent that they always carried adrenaline.
In response, UK authorities 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, this does not mean they should be eager to get the vaccine,” Stephen Evans, professor of pharmacoepidemiology at the London School of Hygiene and Tropical Medicine, told the Science Media Center (SMC).
“You have to remember that even things like the kettle can cause severe and unexpected allergic reactions,” he added.
Those responsible for the clinical trial anticipated the risk, excluding volunteers with a history of serious allergic reactions to vaccines in general or to any of their components.
Millions of people with allergies to common substances like eggs and nuts do not appear to be allergic to the vaccine.
“It will now be important to understand the specific nature of the reactions and the medical history of affected individuals,” Graham Ogg, Acting Director of the Human Immunology Unit at Oxford Medical Research Council, told SMC.
Long-term
Because the vaccines are new, scientists are not sure about possible long-term side effects.
Although they could be authorized for emergency use due to the pandemic, your data will be continuously monitored by global health authorities so they can react immediately.
“As is normal for any vaccine, close and ongoing monitoring of safety and efficacy data as it is released will be essential,” said Dr. Charlie Webber, director of vaccines for the charity Wellcome, according to SMC.
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