Do Swine Glycohumanized Polyclonal Anti-SARS-CoV-2 Antibodies (XAV-19) for COVID-19-Related Moderate Pneumonia cause more adverse events in comparison to placebo? – An Update

Objective: To test whether selection bias has affected the reported adverse event risk for XAV-19 antibodies in comparison to placebo (Risk Difference, -0.20; 95%CI: -0.61 to 0.21; p = 0.34). Method: Trial adjusted, simulated comparator trial (SCT) based I2 test for single randomised controlled trials, using revised I2 threshold limits. Result: A baseline covariate imbalance, either due to chance or due to selection bias was established, being equivalent to selection bias level = B% 70-80 (Bias category = 4). This level suggests that 70-89% of (7 – 9 of the total 10) subjects were non-randomly allocated in favour of one treatment group above the other. Conclusion: The adverse event estimate reported by the tested trial does not suggest any significant differences between XAV-19 antibodies and placebo. However, the selection bias level, estimated by use of the trial adjusted, SCT based I2 test for single RCTs (B% = 70-80), appears to be high enough in order to have affected the reported estimate. In line with new findings, this report updates previous report to the same RCT: EBSM Volume 2, Issue 1, 2026 Pages 9-12, DOI: 10.5281/zenodo.17760785.