Abstract
ObjectivesTo identify individual characteristics associated with serological COVID-19 vaccine responsiveness and the durability of vaccine-induced antibodies. MethodsAdults without history of SARS-CoV-2 infection from the Danish population scheduled for SARS-CoV-2 vaccination were enrolled in this parallel group, phase 4 study. SARS-CoV-2 Spike IgG and Spike-ACE2-receptor-blocking antibodies were measured at days 0, 21, 90, and 180. Vaccine responsiveness was categorized according to Spike IgG and Spike-ACE2-receptor-blocking levels at day 90 after first vaccination. Nondurable vaccine response was defined as day-90 responders who no longer had significant responses by day 180. ResultsOf 6544 participants completing two vaccine doses (median age 64 years; interquartile range: 54–75), 3654 (55.8%) received BTN162b2, 2472 (37.8%) mRNA-1273, and 418 (6.4%) ChAdOx1 followed by an mRNA vaccine. Levels of both types of antibodies increased from baseline to day 90 and then decreased to day 180. The decrease was more pronounced for levels of Spike-ACE2-receptor-blocking antibodies than for Spike IgG. Proportions with vaccine hyporesponsiveness and lack of durable response were 5.0% and 12.1% for Spike IgG and 12.7% and 39.6% for Spike-ACE2-receptor-blocking antibody levels, respectively. Male sex, vaccine type, and number of comorbidities were associated with all four outcomes. Additionally, age ≥75 years was associated with hyporesponsiveness for Spike-ACE2-receptor-blocking antibodies (adjusted odds ratio: 1.59; 95% confidence interval: 1.25–2.01) but not for Spike IgG. DiscussionComorbidity, male sex, and vaccine type were risk factors for hyporesponsiveness and nondurable response to COVID-19 vaccination. The functional activity of vaccine-induced antibodies declined with increasing age and had waned to pre-second-vaccination levels for most individuals after 6 months.
Highlights
Reports on effects of COVID-19 booster vaccination against symptomatic and severe COVID-19 suggested dramatic drops in the risk of infection after administration of a third vaccine dose [1]
Only sparse information on predictors associated with serological COVID-19 vaccine responsiveness and durability exist from clinical phase 2 and 3 trials, as most individuals with significant immunodeficiency were excluded from these trials [8e11]
We prospectively performed comprehensive SARS-CoV-2 serological profiling of more than 6500 individuals enrolled in the Danish National Cohort Study of Effectiveness and Safety of SARS-CoV-2/COVID-19 vaccines (ENFORCE)
Summary
Reports on effects of COVID-19 booster vaccination against symptomatic and severe COVID-19 suggested dramatic drops in the risk of infection after administration of a third vaccine dose [1]. Out of concern of waning immunity and nonprotective levels of antibodies, health authorities in many countries recommend booster vaccination to specific risk groups based on comorbidities and/or age [2,3], or to the entire adult population in some countries [4,5]. We prospectively performed comprehensive SARS-CoV-2 serological profiling of more than 6500 individuals enrolled in the Danish National Cohort Study of Effectiveness and Safety of SARS-CoV-2/COVID-19 vaccines (ENFORCE). We used this dataset to discriminate COVID-19 vaccine responders from nonresponders and to determine risk factors for vaccine hyporesponsiveness and reduced durability of vaccineinduced antibodies that may increase the risk of breakthrough infection
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