We’d like to discuss the article “Efficacy and impact of SARS-CoV-2 vaccination on cancer treatment for breast cancer patients: a multi-center prospective observational study [1].” This study found that the total seroconversion rate following the second vaccination was 95.3%, with chemotherapy patients having the lowest seroconversion rate at 81.8% [1]. The data support SARS-CoV-2 vaccination for breast cancer patients, according to Terada et al. [1]; nevertheless, a possible decrease in neutralizing antibody titers after chemotherapy and CDK4/6 inhibitors has raised questions about the influence on long-term infection prevention. But it’s critical to keep an eye out for circumstances that are more challenging. Before the vaccine, a COVID could have occurred, which would have impacted subsequent immunity. Asymptomatic COVID-19 infection is typically not unusual [2]. In the absence of any symptoms, a history of infection cannot rule out previous COVID-19, and the results can be misleading. Even while a single history of infection may not be enough to rule out COVID-19 in the absence of symptoms, it is typically required for the accurate interpretation of a vaccination schedule.