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Review 3: "Adverse reactions to BNT162b2 mRNA COVID-19 vaccine in medical staffs with a history of allergy"

This study claims that although the frequency of adverse reactions was higher in individuals with a subjective history of allergy, vaccination is considered safe. Reviewers agree with the importance of the idea this paper addresses but raise some key issues regarding its methods.

Published onOct 22, 2021
Review 3: "Adverse reactions to BNT162b2 mRNA COVID-19 vaccine in medical staffs with a history of allergy"
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key-enterThis Pub is a Review of
Adverse reactions to BNT162b2 mRNA COVID-19 vaccine in medical staffs with a history of allergy

AbstractSevere acute respiratory syndrome coronavirus 2 (SARS-CoV-2, COVID-19) vaccination is progressing globally. Several adverse reactions have been reported with vaccination against COVID-19. It is unknown whether adverse reactions to COVID-19 vaccination are severe in individuals with allergies. We administered the COVID-19 vaccine to the medical staff at Yamagata University Hospital from March to August 2021. Subsequently, we conducted an online questionnaire-based survey to investigate the presence of allergy and adverse reactions after vaccination and examined the association between allergy and adverse reactions after immunization.Responses were collected from 1586 subjects after the first vaccination and 1306 subjects after the second administration of the BNT162b2 mRNA COVID-19 vaccine. Adverse reactions included injection site pain, injection site swelling, fever, fatigue or malaise, headache, chills, nausea, muscle pain outside the injection site, and arthralgia. The frequency and severity of most adverse reactions were higher after the second vaccination compared to the first. The frequency of some adverse reactions and their severity were higher, and the duration of symptoms was longer in subjects with allergies than in subjects without allergies. Although several participants visited the emergency room for treatment after the first and second vaccinations, nobody was diagnosed with anaphylaxis.Given the serious consequence of COVID-19 and the reported high efficacy of this vaccine against this disease, we conclude that vaccination of allergic individuals is generally recommended.

RR:C19 Evidence Scale rating by reviewer:

  • Potentially informative. The main claims made are not strongly justified by the methods and data, but may yield some insight. The results and conclusions of the study may resemble those from the hypothetical ideal study, but there is substantial room for doubt. Decision-makers should consider this evidence only with a thorough understanding of its weaknesses, alongside other evidence and theory. Decision-makers should not consider this actionable, unless the weaknesses are clearly understood and there is other theory and evidence to further support it.



Although with limitations, this study confirms the results of a similar questionnaire study from Poland that non-allergic adverse effects are more frequently reported in individuals with a history of allergy. Since the reported adverse effects were generally mild and self-limiting, the clinical relevance of the observed difference is limited.

The authors have made some statements in the article that are not correct regarding indications for vaccinating individuals with allergies against COVID-19, eg. "it is difficult to determine whether individuals with allergies can receive the COVID-19 vaccine"; the only contraindication to being vaccinated with Comirnaty is anaphylaxis to the 1st dose or known allergy to excipients (PEG). Recent research data show that even people with a history of severe allergic reactions can tolerate mRNA COVID-19 vaccines, as well as other types, eg. vector COVID-19 vaccines.

Methodological flaws include:

• no clear statement on the survey response rate

• lack of comparison of the study results with the reported frequency of adverse reactions to Comirnaty

• lack of data on the prevalence of allergic diseases in the Japanese population (to enable comparison with the frequencies of specific self-reported allergies in the study)

• lack of possible explanations for the study results by the authors.

Questionnaire-based studies have important limitations, over-reporting being an important one. Prospective cohort studies would provide more relevant results. However, the clinical relevance of the research seems to be limited, since COVID-19 vaccines are well tolerated in both populations, allergic and non-allergic.

The paper needs an English proofreading.

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