Temporal metabolic response to mRNA COVID-19 vaccinations in oncology patients.

Background mRNA COVID-19 vaccines are known to provide an immune response seen on FDG PET studies. However, the time course of this metabolic response is unknown. We here present a temporal metabolic response to mRNA COVID-19 vaccination in oncology patients undergoing standard of care FDG PET. Methods 262 oncology patients undergoing standard of care FDG PET were included in the analysis. 231 patients had at least one dose of mRNA COVID-19 vaccine while 31 patients had not been vaccinated. The SUVmax of the lymph nodes ipsilateral to the vaccination was compared to the contralateral to obtain an absolute change in SUVmax (ΔSUVmax). Results ΔSUVmax was more significant at shorter times between FDG PET imaging and COVID-19 mRNA vaccination, with a median ΔSUVmax of 2.6 (0-7 days), 0.8 (8-14 days), and 0.3 (> 14 days), respectively. Conclusion Consideration should be given to performing FDG PET at least 2 weeks after the COVID-19 vaccine.