Four SARS-CoV-2 vaccine doses or hybrid immunity in patients on immunosuppressive therapies: a Norwegian cohort study

Abstract

Background: Data on response and safety of repeated vaccinations and hybrid immunity in patients with immune-mediated inflammatory diseases on immunosuppressive therapy is needed to further develop vaccination strategies in this vulnerable population. This study aimed to evaluate hybrid immunity and humoral immune response and safety of four SARS-CoV-2 vaccine doses in patients with immune-mediated inflammatory diseases on immunosuppressive therapy.

Methods: This prospective observational Norwegian study of vaccine response to COVID-19 (Nor-vaC) included adult patients aged 18 years and older with immune-mediated inflammatory diseases (rheumatoid arthritis, spondyloarthritis, psoriatic arthritis, Crohn's disease, or ulcerative colitis) on immunosuppressive therapy, who had received four SARS-CoV-2 vaccine doses (vaccine group) or three vaccine doses followed by COVID-19 (hybrid group), and healthy controls receiving three vaccine doses (control group). Patients were recruited from the Division of Rheumatology at Diakonhjemmet Hospital, Oslo, and the Department of Gastroenterology at Akershus University Hospital, Lørenskog. Patients who had COVID-19 before the third vaccine dose, and patients with allergies or intolerances to elements of the vaccine were excluded. Antibodies to the receptor-binding domain of SARS-CoV-2 spike protein (anti-RBD antibodies) were assessed 2-4 weeks following vaccination or COVID-19. This study is registered at Clinialtrials.gov, NCT04798625.

Findings: Between Nov 12, 2021, and April 19, 2022, 1458 participants with immune-mediated inflammatory diseases provided post-vaccination samples at 2-4 weeks following a third vaccine dose. After 544 participants were excluded, 715 (78%) of the remaining 914 participants received the fourth dose of the vaccine, and of these, 536 (75%) provided post-vaccination samples 2-4 weeks after their fourth vaccination (vaccine group). 199 (22%) of the 914 had COVID-19 after their third dose of the vaccine and of these, 167 (84%) provided samples (hybrid group). 256 of the eligible 703 patients had rheumatoid arthritis, 107 had spondyloarthritis, 115 had psoriatic arthritis, 130 had Crohn's disease, and 95 had ulcerative colitis). Median age was 56 years [IQR 45-65], 398 (57%) were women, and 305 (43%) were men. Patients in the vaccine group had higher anti-RBD antibody concentrations following the fourth vaccine dose (median 6192 BAU/ml [IQR 2878-11 243]) than after the third dose (median 5087 BAU/ml [1250-9081]; p< 0·0001), but lower antibody concentrations than the control group following the third dose (median 7595 BAU/ml [5916-12 001]; p< 0·0001). Antibody concentrations were higher in the patients in the hybrid group (23 548 BAU/ml [IQR 11 440-35 935]) than in the vaccine group (p<0·0001). No difference was found in antibody concentrations between the fourth dose of BNT162b2 (full-dose) and mRNA-1273 (half-dose). Patients and controls had a comparable safety profile after both three and four vaccine doses.

Interpretation: Vaccine boosters improve humoral immune responses and are safe in patients with immune-mediated inflammatory diseases on immunosuppressive therapy, and administration should be considered regularly in this patient group. Hybrid immunity with omicron induces a strong humoral response suggesting longer intervals between booster doses in this patient group.

Funding: The South-Eastern Norway Regional Health Authority, The Coalition for Epidemic Preparedness Innovations, Akershus University Hospital.

Figure 1

Study profile

Figure 2

Anti-RBD IgG antibody concentrations (A) Anti-RBD IgG antibody concentrations following the third and fourth vaccine doses in the vaccine group and third vaccine dose in the control group. P values show unadjusted comparisons between the vaccine group and control group, and between third and fourth vaccine dose in the vaccine group. (B) Anti-RBD IgG antibody concentrations following a fourth vaccine dose in the vaccine group and COVID-19 after three vaccine doses in the hybrid group. P values show unadjusted comparisons between the vaccine types (BNT162b2 or mRNA-1273) in the vaccine group, and between the hybrid group and the vaccine group. Violin plot of probability densities, smoothed by a kernel density estimator. Points denote participants, and solid black lines show group medians. RBD=receptor binding domain.

Figure 3

Distribution of anti-RBD antibody concentrations across diagnoses and medication groups in the vaccine and hybrid groups (A) The distribution of anti-RBD antibody concentrations across diagnoses in patients following a series of three and four vaccine doses (vaccine group), and in controls receiving three vaccine doses. (B) The distribution of anti-RBD antibody concentrations across medication groups in patients following a series of three and four vaccine doses (vaccine group), and in controls receiving three doses. (C) The distribution of anti-RBD antibody concentrations across diagnoses in patients with hybrid immunity with COVID-19 following a series of three vaccine doses (hybrid group). (D) The distribution of anti-RBD antibody concentrations across medication groups in patients with hybrid immunity with COVID-19 following a series of three vaccine doses (hybrid group). Violin plot of probability densities, smoothed by a kernel density estimator. Points denote participants, and solid black lines show group medians. Anti-RBD antibody concentrations after the third vaccine dose are marked in light blue, and after the fourth dose (vaccine group) or COVID-19 infection (hybrid group) in red. Anti-RBD antibody concentrations after the third vaccine dose in the control group are shown to the left. RBD=receptor binding domain.

Figure 4

Type and duration of adverse events reported after vaccination among patients (A) and controls (B) Grey, red, blue, and green bars indicate adverse events reported after the first, second, third, and fourth vaccine doses. *Duration not measured.