medwireNews: People with systemic autoimmune myopathies have moderate seroconversion rates following two doses of the Sinovac (CoronaVac) inactivated SARS-CoV-2 vaccine, with reduced immunogenicity relative to that seen in healthy controls, researchers report.
The investigation was carried out as part of the phase 4 CoronavRheum trial, previously reported by medwireNews, which investigated the efficacy and safety of the Sinovac vaccine in 910 people with systemic rheumatic diseases.
For the current study, Samuel Shinjo and colleagues from Universidade de São Paulo in Brazil evaluated vaccine immunogenicity in 53 patients with systemic autoimmune myopathies, most commonly antisynthetase syndrome (47.2%) or dermatomyositis (45.3%), all of whom had stable or low disease activity.
They report in Rheumatology that 64.9% of 37 patients with available data experienced seroconversion, defined as titers of anti-SARS-CoV-2 immunoglobulin (Ig)G antibodies of more than 15.0 UA/mL, 6 weeks after receiving the second dose of the vaccine.
While this indicates that the vaccine elicits “moderate short-term immunogenicity,” the seroconversion rate in the myopathy group was significantly lower than that observed in 79 age- and sex-matched controls without immune-mediated diseases, at 91.1%, say the researchers.
Moreover, geometric mean antibody titers (16.6 vs 58.5 UA/mL) and neutralizing antibody positivity rates (51.4 vs 77.2%) after the second dose were significantly lower among people with myopathy than controls.
The team then evaluated predictors of immunogenicity in the myopathy group, finding that rates of immunosuppressive drug use were significantly lower among the 19 individuals with neutralizing antibodies than the 18 without (73.7 vs. 100%), as was the median patient global activity VAS score (1.0 vs 2.0 points).
“[W]e could not show any specific drug effect due to the limited sample size,” note Shinjo and team.
In the safety analysis, they observed no moderate or severe adverse events, “with only mild and self-limiting side effects” occurring.
“These findings support the recommendation of SARS-CoV-2 vaccination for [myopathy] patients,” they say.
The researchers highlight that people with myopathy only had a “negligible” immune response to the first vaccine dose, “reinforcing the importance of the second dose for these patients.”
medwireNews is an independent medical news service provided by Springer Healthcare Ltd. © 2021 Springer Healthcare Ltd, part of the Springer Nature Group
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