Discover The Side Effects of Covid-19 Vaccines: How Long Do They Last and Why?
Nine out of ten side effects are mild or moderate, due to the activation of the immune system and the consequent inflammatory state.
The side effects of coronavirus vaccines are the subject of the most attention: by manufacturers, pharmacovigilance, and regulatory agencies, but especially by those who have been vaccinated or have not yet done so.
Let’s take a step back: four vaccines are currently in use in Europe, two based on messenger RNA technology (Comirnaty from Pfizer / BioNTech and Moderna) and two on the use of a viral vector (Vaxzevria from AstraZeneca and Janssen from Johnson & Johnson).
In Italy, almost 50 million doses were administered and more than 17 million Italians over 12 years (32.5% of the population) completed the cycle. The most widely used vaccine (as well as the first to be approved) is Pfizer, with 37 million doses administered; followed by AstraZeneca (10 million doses), Moderna (5 million), and Janssen (almost 2 million).
[In Spain, 39.9 million doses have been administered to more than 16 million people, of which 11.9 already have the full regimen. The most used is also Pfizer (28.1 million doses), followed by AstraZeneca (6.8 million), Moderna (3.6), and Janssen (1.1)]
In the latest Pharmacovigilance Report of the Italian Medicines Agency (Aifa), it speaks of 204 reports of adverse effects for every 100,000 doses administered, regardless of the type of vaccine and the severity of the disorder.
The most common are fever, fatigue, headache, muscle and joint pain, injection site pain, chills, and nausea. These are more common after the second dose of mRNA vaccines and after the first dose of AstraZeneca.
Very rare cases of atypical and intracranial venous thrombosis are also related to this last vaccine (1 case per 100,000 first doses administered, no cases after the second dose), mainly in those under 60 years of age, which led to the Italian Ministry of Health, like the Spanish, to decide not to use AstraZeneca in some age groups. Not enough data has yet been collected on the Janssen vaccine.
Regarding the mild-moderate effects and, therefore, not serious, which are 90% of the total, the reaction occurred in most cases (83%) on the same day of vaccination or the next day, and only more rarely did the effect occurs within 48 hours.
After the mRNA vaccines – Pfizer and Moderna – the most frequent reactions are fever, arm pain, fatigue and weakness, chills, and general malaise.
The effects of the viral vector vaccines (AstraZeneca and Janssen) change slightly: fever, tiredness and weakness, chills, and pain at the injection site.
Many women have reported menstrual irregularities after vaccination, but to date, there is no scientific evidence that the two phenomena could be related. Let’s consider two very common effects (fever and arm pain) and a third, particularly annoying one: acute and persistent headache.
Why might my arm be swollen, sore, or red after the injection? Some feel tingly. First of all, it must be said that arm pain, more common with mRNA vaccines, that is, Pfizer and Moderna, is not perceived by everyone and is also common to other vaccines that are not against the coronavirus.
It can develop a few hours after the injection and last for a few hours or days. It is due to the activation of the immune system. The intensity of this activation can depend on several factors: age, sex, stress.
In some subjects, the inflammatory state is more pronounced, but this does not mean that they are more protected than others who were well after the injection. Sometimes arm pain is associated with swollen lymph nodes in the armpit area, which can last for a few days. All these reactions are normal and nothing to worry about.
A US study examined a unique skin reaction that can occur after vaccination with Moderna: an itchy, sometimes painful rash that lasts an average of 5 days. The injection site should not be massaged, if the pain is severe you can apply ice or consult your GP.
The swelling can go beyond the arm, beyond the injection site, and spread to other parts of the body, causing a rise in temperature (fever) and general pain.
As mentioned, fever occurs mainly after the first dose in viral vector vaccines and after the second in mRNA vaccines. It usually occurs within two days of vaccination and disappears within 48 hours.
In case of severe discomfort, after consulting your doctor, you can take paracetamol or ibuprofen (the latter is not indicated during pregnancy).
A sharp and persistent headache after vaccination should not be a cause for concern. If necessary, and after consulting with your doctor, you can take a pain reliever.
On the other hand, there are rare cases in which the headache should alert, but are easily recognizable. The headache produced by cerebral thrombosis is peculiar: stabbing and accompanied by neurological symptoms (difficulty moving and/or speaking double vision).
Even in thrombosis of the veins of the abdomen (atypical site), extremely severe pain is felt in the affected part