Pfizer-biontech COVID-19 vaccine: Suspected allergic reactions to the first dose

ABSTRACT

Background: The coronavirus disease 2019 (COVID-19) was first identified in December 2019 in Wuhan, China. The WHO declared the outbreak a Public Health Emergency of International Concern in January 2020 and a pandemic in March 2020. Until March 28 2021, more than 125 million cases have been confirmed, with more than 2.7 million deaths attributed to COVID-19. On December 21, 2020, the EMA issued an Emergency Use Authorization for Pfizer-BioNTech COVID-19 vaccine to prevent COVID-19, to be administered in 2 separate doses 21 days apart. The aim of this study was to identify and describe the suspected allergic reactions to first dose of Pfizer-BioNTech COVID-19 vaccine in health care professionals of our center. We also aimed to know if these reactions interfered with the compliance of vaccination protocol. Method: All health care professionals that receipt the vaccine were included. A prospective study was carried out using an online questionnaire to access the demographic data, personal allergic history and description of reaction to the vaccine. Results: In our hospital, the vaccination began on December 29, 2020. A total of 3040 first doses were administered. A total of 2095 (69%) questionnaire responses were collected. It was reported 1649 (79%) adverse events. Among these, 16 (1%) were identified as suggestive allergic reaction. These reactions occurred in professionals, 13 cases (81%) female, with a median age of 41 years (28-52y). The median interval from vaccine administration to symptom onset was 6 hours (5 min-48h). Eight professionals had late cutaneous reactions 6 had mild reactions and tolerated the second dose;and 2 had severe reactions and it was decided not to administer the vaccine. The other 8 professionals had immediate reactions 7 performed allergological study that was negative. The second dose vaccine was administered with vigilance and it was observed cutaneous reaction similar to prior reaction in only one case. Conclusion: In our study population, only 0.8% (16 of 2095) had a suggestive allergic reaction to first dose of the Pfizer-BioNTech COVID-19 vaccine. Half of them had immediate reactions and only 1 professional had a reproducible episode with the second dose;the other had late reactions and only 2 (0.1%) professionals did not complete the vaccination protocol. We can conclude that this vaccine has a good safety profile. and that mild reactions do not interfere with compliance with vaccination schedule.