The ongoing Coronavirus Disease 19 (COVID-19) pandemic caused by the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has affected so far 218 countries with over 94 million cases, about 2 million deaths and over 67 million recovered [1], with dramatic effects on communities and healthcare systems [2]. The beginning of mass vaccination campaigns in late 2020 in the USA and in the UK, and from early 2021 in other countries, will help controlling the infection spread and limiting its consequences, also providing indirect protection to non-vaccinated individuals through the mechanism of “herd immunity” [3-5].
