The Dynamics of Changes in the Concentration of IgG against the S1 Subunit in Polish Healthcare Workers in the Period from 1 to 12 Months after Injection, Including Four COVID-19 V... oleh Monika Skorupa, Joanna Szczepanek, Agnieszka Goroncy, Joanna Jarkiewicz-Tretyn, Barbara Ptaszyńska, Paweł Rajewski, Wojciech Koper, Krzysztof Pałgan, Andrzej Tretyn