A longitudinal seroconversion panel shows anti-SARS-CoV-2 antibody levels up to 6.5 months after vaccination with mRNA-1273 (Moderna)
Abstract
Background
Vaccines have emerged as a crucial tool in combatting the COVID-19 pandemic particularly those based on SARS-CoV-2 S-protein mRNA. A crucial aspect of vaccine efficacy is the duration of antibody responses. In this study, a seroconversion panel was created to assess antibody responses to the mRNA-1273 vaccine over time (6.5 months).
Methods
Blood samples collected from 15 healthy adult participants prior to and up to 6.5 months after vaccination with the mRNA-1273 vaccine (Moderna). Serum from these blood samples were analyzed for anti-SARS-CoV-2 antibody activity by chemiluminescent immunoassay.
Results
The immunoassay results showed that one participant was positive for anti-SARS-CoV- 2 antibodies prior to vaccination indicating a prior infection. All participants showed a positive antibody response after the first vaccination. Highest antibody responses were seen after the second dose (41-45 days from the first dose). Subsequent samples collected at 69-75 days, 130-135 days and 221-229 days after the first vaccination showed positive responses but declining levels of anti-SARS-CoV-2 antibodies.
Conclusions
Declining antibody levels in these participants support the use of booster vaccination to increase antibody levels 4-6 months after the initial vaccine series and continued monitoring to assess the durability of COVID-19 vaccine responses. These results are in agreement with other studies showing antibody persistence but declining the antibody levels in the months after immunization with mRNA-based vaccines.
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