Quantitative and qualitative analysis of seroconversion after one year of vaccination with inactivated SARS-CoV-2 vaccine (CoronaVac®) in healthcare workers: Cross-sectional analytical study

• Published in: Journal of virological methods 2025-02, Vol.332, p.115067, Article 115067
• Main Authors: da Silva, Júlia Gomes, Arruk, Viviana Galimberti, Veiga, Glaucia Raquel Luciano da, Sousa, Luiz Vinícius de Alcantara, Alves, Beatriz da Costa Aguiar, Fonseca, Fernando Luiz Affonso, van der Heijden Natário, Inneke Marie
• Format: Article
• Language: English
• Subjects: Adult; Aged; Antibodies; Antibodies, Viral - blood; Brazil; COVID-19; COVID-19 - immunology; COVID-19 - prevention & control; COVID-19 vaccines; COVID-19 Vaccines - administration & dosage; COVID-19 Vaccines - immunology; Cross-Sectional Studies; Female; Health Personnel; Humans; Immunoglobulin G - blood; Inactivated vaccine; Male; Middle Aged; SARS-CoV-2; SARS-CoV-2 - immunology; Seroconversion; Serologic Tests; Spike Glycoprotein, Coronavirus - immunology; Vaccination; Vaccines; Vaccines, Inactivated - administration & dosage; Vaccines, Inactivated - immunology; Young Adult
• ISSN: 0166-0934; 1879-0984; 1879-0984
• DOI: 10.1016/j.jviromet.2024.115067

A descriptive study was carried out with health professionals in Sao Paulo city. Were included individuals vaccinated with 2 doses of the inactivated vaccine. Demographic, clinical and vaccination information was obtained from professionals with or without comorbidities. Two serological assays were used to identify the presence and quantity of anti-Spike IgG in serum samples. 433 healthy healthcare professionals were included and 58.9 % completed the 4 clinical stages of serological assessment. Among adults and elderly people, 25.2 % had chronic diseases (hypertension 50.5 %, diabetes 10 % and obesity 6.5 %). Most individuals have 95 % protection in the first 3 months after the second dose, and 67.68 % protection after 6 months. Total antibodies ranged from 3 to 10 on the reactivity index, and the anti-RBD IgG levels were high. CoronaVac has a 94 % seroconversion rate after 2 doses and can prevent serious cases and outbreaks of the disease, if used on a large scale. •2 doses of inactivated SARS-CoV-2 vaccine show good protection against outbreaks.•Women and younger healthcare workers have higher antibodies rates against SARS-CoV-2.•Immune system senescence is associated with a decline in the immune response.•Previous infection is directly related to a higher rate of seroconversion.•Booster doses are required to ensure long-lasting immunity.