Affiliation:
1. Dipartimento dei Servizi ASST Grande Ospedale Metropolitano Niguarda Milano Italy
2. Etablissement Francais du Sang Marseille France
3. Italian Bone Marrow Donor Registry E.O. Ospedali Galliera Genova Genova Italy
4. Hematology Department Azienda Sanitaria Provinciale di Trapani Castelvetrano Italy
Abstract
Few data exist on the role of genetic factors involving the HLA system on response to Covid‐19 vaccines. Moving from suggestions of a previous study investigating the association of some HLA alleles with humoral response to BNT162b2, we here compared the HLA allele frequencies among weak (n = 111) and strong (n = 123) responders, defined as those healthcare workers with the lowest and the highest anti‐Spike antibody levels after vaccination. Individuals with clinical history of Covid‐19 or positive anti‐nucleocapside antibodies were excluded. We found the common HLA‐A*03:01 allele as an independent predictor of strong humoral response (OR = 12.46, 95% CI: 4.41–35.21, p < 0.0001), together with younger age of vaccines (p = 0.004). Correlation between antibody levels and protection from breakthrough infection has been observed, with a 2‐year cumulative incidence of 42% and 63% among strong and weak responders, respectively (p = 0.03). Due to the high frequency of HLA‐A*03:01 and the need for seasonal vaccinations against SARS‐CoV‐2 mutants, our findings provide useful information about the inter‐individual differences observed in humoral response after Covid‐19 vaccine and might support further studies on the next seasonal vaccines.