Additional doses of SARS-CoV-2 vaccine heighten antibody response in patients with IBD
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SAN DIEGO — Seroconversion rates and antibody response significantly increased after a third dose of SARS-CoV-2 vaccine in patients with inflammatory bowel disease, according to a presenter at Digestive Disease Week 2022.
“Third- and fourth-dose responses were significantly stronger than a two-dose regimen,” Joshua Quan, MSc, a master’s student at the University of Calgary Cumming School of Medicine, told attendees. “Also, the antibody responses decayed over time from second- to third-dose vaccination, which really highlights the need for third-dose vaccination.”
Quan and colleagues conducted a multicenter, prospective cohort study and identified 271 IBD patients who had received at least two doses of SARS-CoV-2 vaccine. Using the SARS-CoV-2 IgG II Quant assay, they analyzed patients for serological response at 8 weeks after the second dose and then after a third dose. Seroconversion, defined as IgG levels of at least 50 AU/mL, served as the primary outcome. Investigators also assessed the geometric mean titer (GMT) and categorized outcomes by prior COVID-19 history.
According to study results, seroconversion occurred for 100% of patients after the third-dose vaccination (n = 96) vs. 94.4% after the second-dose vaccination (n =175). The GMT also was significantly higher in the post-third dose cohort compared with the post-second dose cohort (16,424 AU/mL vs. 3,261 AU/mL).
Of 82 patients with serological data after both the second- and third-dose vaccination, seroconversion rates increased from 97.6% to 100% after the third dose. In addition, the GMT increased after the third dose, with a mean difference of 11,384 AU/mL (P < .0001) between the third and second dose, a significant difference among patients with prior COVID-19 history (11,682 AU/mL; 95% CI, 8,618-14,746; P < .0001) and those without (8,194 AU/mL; 95% CI, 988-15,400).
According to Quan, preliminary fourth-dose data demonstrated similar responses to that of the third dose.
“The next thing that we really need is a correlate between antibody levels and actual protection or decreased risk of infection,” Quan concluded. “This is especially true in the Omicron era, and this is a piece that our lab is working on next.
“In addition, we did not assess neutralizing antibodies or T cell immunity. ... It would be important to understand these in relation to booster doses in relation to new variants.”
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Quan J, et al. Poster 654. Presented at: Digestive Disease Week; May 21-24, 2022; San Diego (hybrid meeting).
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