medwireNews: The Sinovac (CoronaVac) inactivated SARS-CoV-2 vaccine elicits a reduced antibody response in people with rheumatic and musculoskeletal diseases (RMDs) compared with healthy controls, but the short-term immunogenicity is adequate, researchers report.
The phase 4 CoronavRheum trial included 910 adults with RMDs (median age 51 years, 76.9% women) and 182 age- and sex-matched controls who received both doses of the vaccine at a single center in Brazil. In the RMD group the most common diagnosis was inflammatory arthritis (49.6%); 63.0% were taking immunosuppressive drugs and 35.3% were on biologics.
Eloisa Bonfa and colleagues from Universidade de Sao Paulo in Brazil report in Nature Medicine that the “vaccine was immunogenic in patients with [autoimmune rheumatic diseases], but at lower levels” than in control patients.
Specifically, the anti-SARS-CoV-2 immunoglobulin G seroconversion rate 6 weeks after the second vaccine dose was 70.4% in the RMD group and 95.5% in the control group, a significant difference. The rate of neutralizing antibody positivity was also significantly lower in the RMD than the control group, at 56.3% versus 79.3%.
“These data support the use of CoronaVac in patients with [rheumatic diseases], suggesting reduced but acceptable short-term immunogenicity,” write Bonfa and team, noting that “[t]he trial is still ongoing to evaluate the long-term effectiveness/immunogenicity.”
In an exploratory multivariate analysis, they found that older people (≥60 years) in the RMD group, as well as those taking prednisone, methotrexate, mycophenolate mofetil, tumor necrosis factor inhibitors, abatacept, or rituximab, had a reduced likelihood of seroconversion.
The researchers also carried out an exploratory analysis of COVID-19 incidence during the 40 days before and after full vaccination, finding no significant difference in rates of symptomatic cases between the RMD and control groups (4.0 vs 1.6%). In the total study population, the frequency of COVID-19 cases up until 10 days after the second dose was significantly higher than that seen after this timepoint (3.0 vs 0.6%).
“Although not the main objective of this study, these data […] provide preliminary evidence of the short-term efficacy of CoronaVac in prevention of symptomatic COVID-19 cases,” say the investigators.
Noting that the comparable frequency of COVID-19 cases in the RMD and control groups was “unanticipated,” they suggest that this could be “explained by the higher adherence to social isolation” among RMD patients.
Bonfa et al note that their study was limited by the absence of data on disease activity in the RMD group, as well as “lack of assessment of vaccine T cell responses.”
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Nat Med 2021; doi:10.1038/s41591-021-01469-5