Demonstration of antibodies against SARS-CoV-2, neutralizing or binding, in seroconversion panels after mRNA-1273, BNT-162b2 and Ad26.COV2.S vaccine administration.

Seroconversion panels were collected before and after vaccination with three COVID-19 vaccines: two mRNA vaccines (mRNA-1273 and BNT-162b2) and one adenovirus vector vaccine (Ad26.COV2.S). The panels were tested for antibody activity by chemiluminescent immunoassay, ELISA and one was tested in a pseudovirus neutralization assay. Participants positive for anti-SARS-CoV-2 antibodies before vaccination (18.6%) had a higher response to the first vaccine dose than participants who tested negative. For two-dose vaccines, older participants showed a lower response to the first dose than younger participants. All participants showed positive antibody responses after the second vaccine. For the adenovirus vector vaccine, two participants did not generate antibody responses two weeks and two months after vaccination. Three participants were negative at two weeks but positive at two months. Pseudovirus neutralization showed good correlation with antibody activity (correlation coefficient =0.78, p<0.0001). Antibody responses in participants over 45 years old tended to be less robust.

A longitudinal seroconversion panel shows anti-SARS-CoV-2 antibody levels up to 6.5 months after vaccination with mRNA-1273 (Moderna)

BackgroundVaccines 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). MethodsBlood 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. ResultsThe 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. ConclusionsDeclining 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.

Seroconversion panels demonstrate anti-SARS-CoV-2 antibody development after administration of the mRNA-1273 vaccine

Seroconversion panels are an important tool for investigating antibody responses in acute and chronic phases of disease and development of serological assays for viral diseases including COVID-19. Globally it is anticipated that vaccines against SARS-CoV-2 will facilitate control of the current pandemic. The two COVID-19 seroconversion panels analyzed in this study were obtained from consenting donors with samples collected before vaccination with the mRNA-1273 vaccine (Moderna) and after the first and second doses of the vaccine. Panel samples were tested for antibodies to SARS-CoV-2 (IgG). Individual subjects with a positive response for anti-SARS-CoV2 IgG in their pre-vaccination samples showed a significantly enhanced response to the first vaccination. In older subjects, weaker immunological responses to the first injection were observed, which were overcome by the second injection. All subjects in the study were positive for anti-SARS-CoV-2 IgG after the second dose of vaccine.