Those who have had an allergic reaction immediately after receiving the first dose of Covid-19 mRNA vaccine may be fearful of undergoing the second dose, but a systematic review coordinated by the University of Colorado School of Medicine, published in Jama Internal Medicine shows that the risk of a new episode of severe or anaphylactic reaction is very low.
The analysis considered data from 22 studies on vaccination against SARS-CoV-2 infection with mRNA vaccines, from which 1,366 cases (87.8% women) of immediate allergic reactions emerged after first dose of vaccine, 78 of which were severe (analiptaxis). In the same group of people (1,366), the second dose caused 6 severe allergic reactions, 4 of which in people already suffering from anaphylaxis at the first dose.
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by Aureliano Stingi
According to these data, those who had a severe allergic reaction at the first dose have a 5% risk that the problem, of the same magnitude, will also occur at the second. On the other hand, those who have had an allergic reaction at the first dose, but not a serious one, have a risk of a serious reaction of 0.16%.
The study specifies that among the 6 severe allergic cases at the second dose there was no death, 5 patients quickly recovered after receiving adrenaline while the sixth recovered without treatment.
In the remainder of the sample, the second dose caused immediate mild allergy symptoms in 232 people (15 of them were among the 78 who had had severe reactions to the first dose). For the researchers, one can ultimately speak of a general tolerance to the second dose in 99.84% of the total sample.
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“Having had an allergic mRNA vaccine reaction at the first dose does not automatically mean having another just as severe with the second dose. These data should prompt us to reconsider the previous allergic reaction as a contraindication,” the researchers point out. the second dose to these patients should in any case be administered in a medical environment equipped to manage cases of anaphylaxis and after consulting an allergist.