medwireNews: Titers of antibodies against the receptor binding domain (RBD) of the SARS-CoV-2 spike protein following vaccination may predict whether patients with autoimmune rheumatic diseases (AIRDs) are protected against COVID-19, researchers report.
These findings are based on an analysis of 630 people with rheumatic diseases – most commonly rheumatoid arthritis (65.8%) or spondyloarthritis (17.7%) – who had received two doses of a COVID-19 vaccine in India and were followed up every 2 months for breakthrough infections. A total of 78.6% received the adenoviral vector-based AstraZeneca Covishield (ChAdOx1 nCoV-19) vaccine, while the remaining 21.4% were given the indigenous whole-virion β-propiolactone-inactivated Bharat Biotech Covaxin (BBV152) vaccine.
Padmanabha Shenoy (Centre for Arthritis and Rheumatism Excellence, Cochin, India) report that at 4–6 weeks after the second vaccine dose, 60.3% of patients were classified as good responders (anti-RBD titers >212 IU), while 22.7% were inadequate responders (0.8–212 IU) and 16.9% were nonresponders (<0.8 IU).
In all, 7.4% of participants experienced breakthrough SARS-CoV-2 infections at an average follow-up of 147 days postvaccination. The majority (78.7%) of these 47 people experienced mild COVID-19 according to World Health Organization criteria, while 8.5% were asymptomatic, 7.4% had moderate disease, and 3.7% had severe disease.
Shenoy and team say that rates of breakthrough infection were highest in the nonresponder group, at 17.8%, followed by the inadequate and good responder groups, at 9.1% and 4.0%, respectively. Antibody nonresponse, receipt of the Bharat Biotech Covaxin vaccine, and mycophenolate mofetil use were all significantly associated with breakthrough infection risk on univariate analysis.
These factors were all included in a multivariate analysis, which demonstrated that people in the nonresponse group had a significant 3.6-fold higher risk for breakthrough COVID-19 than those in the good response group. None of the other variables were significant predictors of breakthrough infection.
The researchers also evaluated serum neutralization against the B.1.617.2 (delta) variant of SARS-CoV-2 in the 48 people from the good or inadequate responder groups with exposure to a contact with COVID-19. They found that the percentage neutralization of virion particles was significantly higher among people who did not test positive for SARS-CoV-2 following exposure than among those who were infected, at 42.9% versus 14.8%
Writing in the Annals of the Rheumatic Diseases, Shenoy and colleagues say that their study findings provide “evidence for using post-vaccination antibody titres as a biomarker to assess successful vaccination in patients with AIRD.”
medwireNews is an independent medical news service provided by Springer Healthcare Ltd. © 2022 Springer Healthcare Ltd, part of the Springer Nature Group
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Ann Rheum Dis 2022; doi:10.1136/annrheumdis-2021-221922