ABSTRACT
Background: SARS-CoV-2 vaccines efficacy and safety have been tested in phase 3 studies which did not include cancer patients. Information is scarce regarding COVID-19 vaccines safety in this population. Methods: The objective of this study is to evaluate the safety profile of the mRNA-1273 vaccine across cancer patients and its relationship to patients' demographics. This cross sectional study included patients 18-years or older with solid malignancies receiving active treatment in Hospital Clínico San Carlos (Madrid, Spain) who had received the three dose schedule of the mRNA9 1273 vaccine. Patient electronic medical records were reviewed retrospectively to collect data between April 19, 2021 and December 31, 2021. Patients with documented previous infection by SARS-Cov-2 were excluded. Results: 93 patients met inclusion criteria. 31 patients (33%) were male and 62 patients (66%) were female. Mean age was 61 [SD 8]. 33% of the study population had metastatic disease. The majority of patients (60%) had ECOG 0 whereas 32% and 8% of the population had ECOG 1 and 2 respectively. Most common tumors were breast (33%) and gastrointestinal (17%). Treatment modalities included chemotherapy (37%), targeted therapy (23%), immunotherapy (12%) and combined therapy (28%). Local adverse effects at the site of injection and systemic adverse reactions had different trends, local adverse reactions were reported more frequently after the first and second dose than after the third (42%, 50% and 36% respectively), while systemic adverse reactions were reported less frequently after the first and second dose than after the third (16%, 35% and 53% respectively). Most common systemic adverse effect was fever followed by malaise and myalgia. No grade 4 or 5 adverse events were reported. We found a statistically significant association between sex and systemic adverse reactions after the third dose with a moderate correlation assessed by Cramer's V. Cochran-Armitage test showed a statistically significant linear trend, p = 0.012, with higher ECOG score associated with a lower proportion of patients suffering from systemic side effects. A logistic regression showed that females had 5.79 times higher odds to exhibit systemic adverse events after the third dose (p = 0.01) compared to males. Increasing age was associated with a decreased likelihood of exhibiting adverse events (p = 0.016). ECOG scores didn't show a statistically significant association. Conclusions: mRNA-1273 vaccine shows a tolerable safety profile, which is similar to the non-oncologic population. The likelihood of adverse reactions appears to be associated with gender and age. Its association with ECOG scores is less evident. Further studies are needed to elucidate the safety profile of COVID-19 vaccines in cancer patients.