We present the case of a 79-year-old woman with moderately differentiated adenocarcinoma of the right adnexa, who had a transient increase in CA-125 levels after a period, during which she underwent treatment for COVID-19 infection and received the first dose of COVID-19 mRNA (Pfizer-BioNTech) vaccine with no evidence of disease progression on imaging. The gene discussed is MUC16; the disease is adenocarcinoma.