Introduction: SARS-CoV-2 vaccines efficacy and safety have been tested in phase 3 studies in which cancer patients were not included or underrepresented. Information is scarce regarding 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 our hospital who had received the three dose schedule of the mRNA9 1273 vaccine and whose side effects after each dose were recorded. Patient electronic medical records were reviewed retrospectively to collect tha available information in 2021. Patients with documented previous infection by SARS-Cov-2 were excluded from the study.

Results: 93 patients met inclusion criteria. Local adverse drug reactions (ADRs) were reported more frequently after the first and second dose than after the third (41.9%, 43% and 31.1% of the patients respectively), while systemic ADRs were reported less frequently after the first and second dose than after the third (16.1%, 34.4% and 52.6% of the patients respectively). We found  a statistically significant association between sex and systemic ADRs after the third dose.  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 ADRs after the third dose (p=0.01)  compared to males. Increasing age was associated with a decreased likelihood of exhibiting ADRs (p=0.016).

Conclusion: mRNA-1273 vaccine shows a tolerable safety profile. The likelihood of ADRs appears to be associated with gender and age. Its association with ECOG scores is less evident. Further studies are needed to elucidate this data in cancer patients.

Study Design, Eligibility and Study Procedures.

This observational retrospective study included patients with solid tumors receiving anticancer treatment at the outpatient facility of the Hospital Clínico San Carlos Medical Oncology service in Madrid, Spain. We included all the patients vaccinated with  mRNA-1273 vaccine that were on active anticancer therapy and had complete available information about the date of each vaccination dose and side effects for each of the three doses in electronic medical records. Patients who had a documented SARS-CoV-2 infection or a positive SARS-CoV-2 serology test collected during routine clinical practice in the 7 days prior to the first mRNA-1273 vaccine dose were excluded. 

Additional clinical information was abstracted from the electronic medical record, including age, sex, performance status (PS) cancer type, cancer history, cancer stage, cancer therapy before enrollment.

Patient electronic medical records were reviewed retrospectively to collect available information in 2021.

The Comité de Ética del Medicamento e Investigación Clínica (Ethics Committee) of Hospital Clínico San Carlos approved the project with the code: 22/033-E.

Data Analysis

The primary end point of this study was ADRs after each dose of mRNA-1273 VACCINE. ADRs were categorized as local adverse reactions which included pain, swelling, rash and itchiness at the site of infection and systemic adverse reactions. Systemic adverse reactions reported by patients were fever (defined as body temperature equal or above 38ºC), headache, myalgia, malaise, nausea, arthralgia, chills, adenopathies, urticaria, asthenia and cough.

Data was analyzed with IBM SPSS v.25. For descriptive purposes, categorical variables were represented by absolute and relative frequencies and quantitative variables were represented by central and dispersion measures. In order to ascertain the relationship between nominal independent variables (sex, heavily trated status and past story of systemic adverse drug reactions) we performed a Chi-squared test (all expected cell frequencies were greater than five) followed by a Cramer’s V test. For ordinal variables (Eastern Cooperative Oncology Group performance status) we performed a Cochran-Armitage Test of trend. Significance was tested with an alpha value of 0,05. No multiplicity correction was applied. In order to test the value as predictors of true baseline variables (age, sex and Eastern Cooperative Oncology Group performance status) we fitted a binomial logistic regression to ascertain the effects of age, sex and ECOG score on the likelihood that participants have systemic adverse events after the third dose (hereinabove described). Linearity of the continuous variables with respect to the logit of the dependent variable was assessed via the Box-Tidwell procedure. A Bonferroni correction was applied using all seven terms in the model resulting in statistical significance being accepted when p < 0.0071. Age was included as a continuous variable, sex as a dichotomous variable, being male considered as reference, and ECOG score was included as categorical variables, being considered a score of 0 the reference.