Digestive Disease Week Additional doses of SARS-CoV-2 vaccine increase antibody response in patients with IBD

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SAN DIEGO – Seroconversion rates and antibody response increased significantly after a third dose of the SARS-CoV-2 vaccine in patients with inflammatory bowel disease, according to a presenter at Digestive Disease Week 2022.

“The third- and fourth-dose responses were significantly stronger than a two-dose regimen,” Joshua Quan, MSc, a master’s student at Cumming University School of Medicine at the University of Calgary, told attendees. “In addition, antibody responses decreased over time from the second to the third dose of vaccination, which really highlights the need for the third dose of vaccination.”

When he and his colleagues conducted a multicenter, prospective cohort study, they identified 271 patients with IBD who had received at least two doses of the 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. The researchers also evaluated the geometric mean titer (GMT) and classified the results according to the previous history of COVID-19.

According to the results of the study, seroconversion occurred in 100% of patients after the vaccination of the third dose (n = 96) compared to 94.4% after the vaccination of the second dose (n = 175 ). GMT was also significantly higher in the post-third dose cohort compared to the post-second dose cohort (16,424 AU / mL versus 3,261 AU / mL).

Of the 82 patients with serological data after the second and third dose vaccination, seroconversion rates increased from 97.6% to 100% after the third dose. In addition, GMT increased after the third dose, with a mean difference of 11,384 AU / mL (P <0.0001) between the third and second dose, a significant difference between patients with a previous history of COVID- 19 (11,682 AU / mL; 95% CI, 8,618–14,746; P <0.0001) and those without (8,194 AU / ml; 95% CI, 988–15,400).

According to Quan, preliminary data from the fourth dose showed similar responses to the third dose.

“The next thing we really need is a correlation 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.

“Furthermore, we did not evaluate neutralizing antibodies or the immunity of T cells. … It would be important to understand this in relation to booster doses in relation to the new variants.”

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