C. Mattiuzzi, B. M. Henry, F. Sanchis-Gomar, and G. Lippi, “SARS-CoV-2 recurrent RNA positivity after recovering from coronavirus disease 2019 (COVID-19): a meta-analysis”, Acta Biomed, vol. 91, no. 3, p. e2020014, Sep. 2020, doi: 10.23750/abm.v91i3.10303.