INTRODUCTION: Coronavirus disease (Covid-19) has claimed more than 4 million deaths worldwide by 13th August, 2021. In December 2020, Covid-19 vaccination campaign started. Nowadays, around 4.6 billion doses have been administered. The aim of this study is to detect if people with SARS-CoV-2 prior infection suffer more adverse effects to messenger ribonucleic acid (mRNA) vaccine, compared to people without this background.
MATERIAL AND METHODS: All health workers from Fundación Jiménez Díaz University Hospital (Madrid, Spain), who reported local and general adverse effects after SARS-CoV-2 mRNA vaccine administration, were recruited between January and February, 2021. Age, sex, number of doses, professional category and department were studied as independent variables. The dependent variable selected was positive polymerase chain reaction (PCR) test and/or positive immunoglobulin G (IgG) against SARS-CoV-2.
RESULTS: 200 out of a total of 4,665 healthcare workers, who received mRNA vaccine at the hospital in that period of time, reported adverse effects. Regarding local symptoms, a lower risk of presenting them was observed after the administration of the second dose (OR 0.19, 95% CI 0.10-0.37, p <0.001). Attending to general symptoms, the results indicate older workers (OR 0.93, 95% CI 0.86-0.99, p = 0.045) had fewer symptoms.
CONCLUSIONS: An association between SARS-CoV-2 prior infection and more adverse effects to mRNA vaccine was not found in our study of hospital healthcare workers. Furthermore, variable “age” needs to be further investigated, since younger people seem to have more adverse effects to the vaccine.
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