For patients with systemic lupus erythematosus (SLE), the risk for breakthrough COVID-19 infection is lower among those who have received a booster vaccine dose after initial vaccination, according to research published in The Lancet Rheumatology. Amit Saxena, MD, and colleagues examined the effect of the initial vaccination series and an additional dose on COVID-19 infection, morbidity, and seroreactivity in patients with SLE, with clinical follow-up on or after February 4, 2022 and at least 6 months since initial vaccination. In 57 patients, longitudinal serologic evaluation of the SARS-CoV-2 spike receptor binding domain antibody was performed. Breakthrough infections occurred among 22% of patients who received an additional COVID-19 vaccine dose, compared with 42% of those who did not. Among those with breakthrough infections, 64% had received an additional dose, while 82% of those without breakthrough infections had received an additional dose.