A Covid-19 second dose is safe for individuals who experienced a severe allergic reaction during their first vaccination, according to a meta-analysis conducted by McMaster University in Hamilton, Canada. The study found that a second dose of an mRNA vaccine is safe for those who experienced an allergic reaction during their first vaccination, as long as the vaccination and subsequent observation of the patient occur in a supervised environment where any potential allergic reactions can be quickly treated by medical professionals. The researchers analyzed 22 studies involving 1,366 individuals who experienced an allergic reaction, such as anaphylaxis, within four hours of their first Covid-19 vaccination with an mRNA vaccine. Of these individuals, 78 (5.71%) experienced severe side effects. However, during their second vaccination, only six individuals (0.16%) experienced a severe allergic reaction, while the remaining 99.84% did not experience any allergic reactions.
The study, published in the JAMA medical journal, found that a second dose of the vaccine under the supervision of an allergist is safe, and there were no deaths resulting from the vaccination or allergic reactions. Of the six patients who experienced a severe allergic reaction after their second vaccination, five received a dose of adrenaline and quickly recovered, while the other patient recovered without receiving adrenaline. Additionally, 232 individuals (13.65%) experienced a mild allergic reaction after their second vaccination, and 15 of the 78 individuals (9.54%) who experienced severe allergic symptoms after their first vaccination experienced mild allergic symptoms after their second vaccination. Measures to reduce the risk of allergic reactions, such as preventive medication or a lower vaccine dose, did not affect the results.
The authors of the study concluded that the Covid-19 vaccine is a highly effective strategy for protecting against infections and severe Covid-19 cases. The risk of an allergic reaction or anaphylaxis after the second vaccination is low, even for individuals who experienced an allergic reaction after their first vaccination.
