Introduction

The initiation of vaccination against Covid-19 raises some questions about the effectiveness, safety, durability of protection and the need for booster doses. The measurement of anti-spike IgG antibodies can help to answer these questions, as well as to reduce the contagion between Health Professionals and patients, ensuring the responsiveness of the National Health Service.

Objectives

Assess the anti-spike IgG antibody titles in vaccinated healthcare professionals at three and six months after full vaccination and how they vary with age.

Methodology

Anti-spike IgG antibodies against SARS-CoV2 were measured in a group of 923 health professionals from a Local Health Unit at three and six months after vaccination with the COMIRNATY® vaccine. The serological test used was the fully automated chemiluminescent immunoassay (Abbott). Epidemiological data was collected, such as Age, Gender and Professional Category, and it was determined whether there was a relationship between antibody titles and age.

Results

Of the 923 participants, the majority were women (81.4%), and the mean age was 45.51 years. Antibody titles averaged 6452.61 AU/mL at three months and 2011.17AU/mL at six months, with a drop of 68.84% from three to six months. From the results obtained, it can be noted that antibody values vary with age: the older the age, the lower the number of antibodies produced, and from three to six months this association is stronger, that is, older people produce fewer antibodies, and they lose them intensely over time.

Discussion/Conclusion

The measurement of IgG anti-spike antibodies cannot be seen as a unique measure of vaccine efficacy, there is also an important component of humoral immunity that we still do not know for sure the true importance. Antibody dosing may provide relevant information about efficacy, the need for vaccine booster, identification of risk groups and contributing to disease prevention in Health Professionals. This study allows us to identify that most people responded well to vaccination, but that the antibodies drop sharply from three to six months. It also makes it possible to establish a relationship, albeit tenuous, between age and antibody titles, reinforcing the idea of boosting vaccination in older people.

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