SARS-CoV-2 infection in cancer patients on active therapy after the booster dose of mRNA vaccines

Abstract

Introduction: The protective role against SARS-CoV-2 infection by the third booster dose of mRNA vaccines in cancer patients with solid malignancies is presently unknown. We prospectively investigated the occurrence of COVID-19 in cancer patients on active therapy after the booster vaccine dose.

Methods: Cancer patients on treatment at the Center for Immuno-Oncology (CIO) of the University Hospital of Siena, Italy, and health care workers at CIO who had received a booster third dose of mRNA vaccine entered a systematic follow-up monitoring period to prospectively assess their potential risk of SARS-CoV-2 infection. Serological and microneutralization assay were utilized to assess levels of anti-spike IgG, and of neutralizing antibodies to the SARS-CoV-2 Wild Type, Delta and Omicron variants, respectively, after the booster dose and after negativization of the nasopharyngeal swab for those who had developed COVID-19.

Results: Ninety cancer patients with solid tumors on active treatment (Cohort 1) and 30 health care workers (Cohort 2) underwent a booster third dose of mRNA vaccine. After the booster dose, the median value of anti-spike IgG was higher (p = 0.009) in patients than in healthy subjects. Remarkably, 11/90 (12%) patients and 11/30 (37%) healthy subjects tested positive to SARS-CoV-2 infection during the monitoring period. Similar levels of anti-spike IgG and of neutralizing antibodies against all the investigated variants, with geometric mean titers of neutralizing antibodies against the Omicron being the lowest were detected after the booster dose and after COVID-19 in both Cohorts.

Conclusions: The occurrence of SARS-CoV-2 infection we observed in a sizable proportion of booster-dosed cancer patients and in healthy subjects during the Omicron outbreak indicates that highly specific vaccines against SARS-CoV-2 variants are urgently required.

Keywords: Cancer patients; SARS-CoV-2 infection; mRNA vaccines.

Fig. 1

Anti-spike IgG response and neutralising antibodies to SARS-CoV-2 WT, Delta and Omicron variants by a booster dose of mRNA vaccines and after SARS-CoV-2 infection in cancer patients and healthy subjects. Levels of circulating anti-spike IgG were assessed in cancer patients and in healthy subjects after the booster dose of the mRNA-1273 (Moderna) or BNT162b2 (Pfizer-BioNTech) vaccine and after SARS-CoV-2 infection. Differences between titres of anti-spike IgG in cancer patients and healthy subjects are reported (Panel A, B). In each box-and-whisker plot, the horizontal line represents the median, the top and bottom of the box show the interquartile range, and the whiskers show the minimum and maximum values. Each dot represents individual serum sample. Titres of neutralising antibodies to SARS-CoV-2 wild type (WT), Delta and Omicron variants in cancer patients and healthy subjects are reported in Panel C, D. In each scatter plot, GMTs (horizontal lines) with 95% CI are presented. Dots indicate individual serum samples. Correlation between titre of neutralising antibodies to SARS-CoV-2 WT, Delta and Omicron variants and levels of circulating anti-spike IgG was evaluated in cancer patients (Panel E, F) and healthy subjects (Panel E, F). Symbols indicate individual serum samples. The P values lt;0.05 were considered statistically significant.