Detection of sars-cov-2 infection prevalence in 474 hematologic patients under therapy with a triple screening procedure including triage, molecular nasopharyngeal swab and rapid serological test
Authors: A. Candoni, G. Petruzzellis, S. Volpetti, G. Facchin, R. Stocchi, J. Olivieri, C. Marcon, A. Sperotto, V. Radici, R. Mullai, C. Comuzz, F. Calabro, R. Fanin
Journal: HemaSphere (2021)

Background: There are still limited epidemiological data regarding the efficacy and performance of screening procedures to detect the prevalence of SARS-CoV-2 infection (including symptomatic cases and asymptomatic carriers) in hematologic outpatients undergoing active anticancer therapy. Aims: The primary endpoint of the study was to estimate the effective prevalence of SARS-CoV-2 infection (including silent and symptomatic cases) in consecutive and unselected hematologic outpatients under anticancer therapy. Methods: Between May1, 2020, and June 15, 2020 (under first wave of SARS-CoV-2 pandemic), 474 consecutive hematologic patients (pt) undergoing anticancer therapy, were evaluated and tested for SARSCoV- 2 with a combined screening procedure, including triage, molecular nasopharyngeal swab (NPS) and rapid serological immunoassay (for anti- SARS-CoV-2 IgG/IgM). The most frequent neoplasms was: lymphoma in 198 case, multiple myeloma in 103 cases, acute leukemia in 83 cases. Results: Overall, 1263 SARS-CoV-2 NPS (median/pt=3 NPS, range 1-9) and 474 serological tests (one for each pt), were performed. At triage questionnaire, a total of 60 (13%) pt self-reported symptoms potentially COVID-19 related. The presence of symptoms (mainly fever > 37°C) was more frequent in pt with acute leukemia (23%), myelodysplastic syndromes (50%) and lymphomas (14%). SARS-CoV-2 NPS was positive in 0% of cases, but in 8 pt (1.7%) the specific serological test was positive (4/8 IgM and IgG positive and 4/8 only IgM positive). The prevalence of SARS-CoV-2 infection, in this tested neoplastic population, was 1.7% and, of the 60 cases who declared symptoms potentially COVID-19- related (positive triage), only 1/60 (1,6%) was found to be SARS-CoV-2 positive. Summary/Conclusion: 1) This is a large study detecting the prevalence of SARS-CoV-2 infection (including asymptomatic cases) in oncohematologic pt receiving active therapy, during the first epidemic peak and under the restrictive lockdown measures, in one of the active areas of the SARS-CoV-2 circulation. Our findings suggest that a questionnaire- based triage system, even if accurate and important, has a low predictive value for the identification of cancer patients with SARS-CoV-2 infection since a differential diagnosis between tumor related symptoms (such as fever, cough or dyspnea) and COVID-19 related symptoms is always very difficult. 2) Lacking specific recommendations for the detection of asymptomatic SARS-CoV-2 infection carriers, a combined diagnostic screening (including triage +NPS +serological test) could be useful in detecting the right prevalence of SARS-Cov-2 infection in neoplastic pt populations including silent infection cases. This prevalence data can obviously be variable according to the territorial context, to the entity of the restrictive measures adopted and to the epidemic curve. Nevertheless, its knowledge is important to balance risks/benefits of oncologic treatments and to avoid, if the prevalence is low, the reduction of dose intensity or a selection of less intensive, but also less effective, anticancer therapies.