ABSTRACT
To obtain more insight into IgM in anti-SARS-CoV-2 immunity a prospective cohort study was carried out in 32 volunteers to longitudinally profile the kinetics of the anti-SARS-CoV-2 IgM response induced by administration of a three-dose inactivated SARS-CoV-2 vaccine regimen at 19 serial time points over 456 days. The first and second doses were considered primary immunization, while the third dose was considered secondary immunization. IgM antibodies showed a low secondary response that was different from the other three antibodies (neutralizing, total, and IgG antibodies). There were 31.25% (10/32) (95% CI, 14.30-48.20%) of participants who never achieved a positive IgM antibody conversion over 456 days after vaccination. The seropositivity rate of IgM antibodies was 68.75% (22/32) (95% CI, 51.80-85.70%) after primary immunization. Unexpectedly, after secondary immunization the seropositivity response rate was only 9.38% (3/32) (95% CI, 1.30-20.10%), which was much lower than that after primary immunization (p = 0.000). Spearman's correlation analysis indicated a poor correlation of IgM antibodies with the other three antibodies. IgM response in vaccinees was completely different from the response patterns of neutralizing, total, and IgG antibodies following both the primary immunization and the secondary immunization and was suppressed by pre-existing immunity induced by primary immunization.
ABSTRACT
Background: Due to anti-SARS-CoV-2 antibody decay and SARS-CoV-2 variants, vaccine booster doses are a constant concern. It was focused on whether the third dose can quickly evoke and activate immunity and produce a sufficient and durable immune protection. Objectives: To evaluate the responses and durations of five subsets of anti-SARS-CoV-2 antibodies and their predictive values for protection after the administration of a three-dose inactivated SARS-CoV-2 vaccines regimens. Methods: A prospective cohort study of five subsets of anti-SARS-CoV-2 antibodies (neutralizing antibody, anti-RBD total antibody, anti-Spike IgG, anti-Spike IgM, and anti-Spike IgA) was carried out to evaluate the efficacies and immune characteristics of a three-dose inactivated SARS-CoV-2 vaccines regimen in 32 volunteers. The dynamic response and immune decay were longitudinally profiled at 18 serial time points over 368 days. Results: The neutralizing antibody, anti-RBD total antibody, anti-Spike IgG and anti-Spike IgA levels rapidly increased to 773.60 (380.90-1273.00) IU/mL, 639.30 (399.60-878.60) AU/mL, 34.48 (16.83-44.68) S/CO and 0.91 (0.35-1.14) S/CO, respectively, after the administration of the third dose. Compared to the peak value after the second dose, these values were increased by 4.22-fold, 3.71-fold, 1.01-fold and 0.92-fold. On the other hand, the half-lives of the neutralizing antibody, anti-RBD total antibody, and anti-Spike IgG were 56.26 (95% CI, 46.81 to 70.49) days, 66.37 (95% CI, 54.90 to 83.88) days, and 82.91 (95% CI, 63.65 to 118.89) days, respectively. Compared to the half-lives after the second dose, these values were increased by 1.71-fold, 2.00-fold, and 2.93-fold, respectively. Nevertheless, the positive conversion rate of anti-Spike IgM was decreased to 9.38% (3/32), which was much lower than that after the second dose (65.63% (21/32)). Conclusions: Compared to the second dose, the third dose dramatically increased the antibody levels and decay times. However, the half-life of neutralizing antibody remained unsatisfactory. Due to decay, a fourth dose, and even annual revaccination, might be considered in the SARS-CoV-2 vaccination management strategy.
Subject(s)
COVID-19 , SARS-CoV-2 , Antibodies, Neutralizing , Antibodies, Viral , COVID-19/prevention & control , COVID-19 Vaccines , Cohort Studies , Humans , Immunoglobulin A , Immunoglobulin G , Immunoglobulin M , Prospective Studies , Vaccines, InactivatedABSTRACT
Background A vaccine against coronavirus disease 2019 (COVID-19) with highly effective protection is urgently needed. The anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibody response and duration after vaccination are crucial predictive indicators. Objectives To evaluate the response and duration for 5 subsets of anti-SARS-CoV-2 antibodies after vaccination and their predictive value for protection. Methods We determined the response and duration for 5 subsets of anti-SARS-CoV-2 antibodies (neutralizing antibody, anti-RBD total antibody, anti-Spike IgG, anti-Spike IgM, and anti-Spike IgA) in 61 volunteers within 160 days after the CoronaVac vaccine. A logistic regression model was used to determine the predictors of the persistence of neutralizing antibody persistence. Results The seropositivity rates of neutralizing antibody, anti-RBD total antibody, anti-Spike IgG, anti-Spike IgM, and anti-Spike IgA were only 4.92%, 27.87%, 21.31%, 3.28% and 0.00%, respectively, at the end of the first dose (28 days). After the second dose, the seropositivity rates reached peaks of 95.08%, 100.00%, 100.00%, 59.02% and 31.15% in two weeks (42 days). Their decay was obvious and the seropositivity rate remained at 19.67%, 54.10%, 50.82%, 3.28% and 0.00% on day 160, respectively. The level of neutralizing antibody reached a peak of 149.40 (101.00–244.60) IU/mL two weeks after the second dose (42 days) and dropped to 14.23 (7.62–30.73) IU/mL at 160 days, with a half-life of 35.61(95% CI, 32.68 to 39.12) days. Younger participants (≤31 years) had 6.179 times more persistent neutralizing antibodies than older participants (>31 years) (P<0.05). Participants with anti-Spike IgA seropositivity had 4.314 times greater persistence of neutralizing antibodies than participants without anti-Spike IgA seroconversion (P<0.05). Conclusions Antibody response for the CoronaVac vaccine was intense and comprehensive with 95.08% neutralizing seropositivity rate, while decay was also obvious after 160 days. Therefore, booster doses should be considered in the vaccine strategies.