Clinical Application of Chemiluminescence Microparticle Immunoassay (CMIA) to Measure Antibody Responses After 18 Months of Covid-19 Vaccination and Comparison with Enzyme-Linked Immunosorbent Assay (ELISA)

Abstract

Background/Aim: This study aims to compare the clinical application of the CMIA and ELISA methods in measuring antibody responses after 18 months of COVID-19 vaccination with Sinovac and AstraZeneca. By comparing the sensitivity, specificity, and accuracy of the two methods, it is hoped that we can gain a better understanding of their effectiveness in monitoring the immune response to COVID-19 vaccination over an extended period.

Materials and Methods: The study design is longitudinal. Participants were individuals vaccinated against COVID-19 with Sinovac and AstraZeneca in the previous 18 months. Data collection involved interviews and blood sampling. Antibody response measurements were conducted using the CMIA method, with some samples measured using ELISA for comparison. Data analysis was performed using SPSS software v25.0 and the Microsoft Excel package. An independent t-test was used to compare antibody responses between baseline and 18 months after vaccination. Additionally, a paired sample t-test was used to compare the CMIA and ELISA methods.

Results: The majority of research subjects were women (67.2%), aged 18 to 44 years (9.2%), with an average age of 41.45 years; 58% had completed high school education, and 48% had a normal body mass index. AstraZeneca vaccine recipients outnumbered Sinovac recipients. Before vaccination, 65.4% had SARS-CoV-2 antibodies, with the highest proportion of positive antibodies among females (69.6%), those aged 18–44 years (59.2%), those with a high school education (45.7%), those with a normal weight (55.6%), and those who received the AstraZeneca vaccine (72.3%). After 18 months, all research subjects still showed positive antibody results, with the average antibody titer for AstraZeneca higher than for Sinovac. The analysis revealed no significant difference between results obtained using the CMIA and ELISA methods (p = 0.992).

Conclusion: The majority of participants showed a positive antibody response at baseline, which persisted at 18 months after vaccination. The average antibody response was higher in participants given AstraZeneca compared to Sinovac. There were no significant differences in measuring antibody responses with CMIA and ELISA.