PSMD1 and infection: This included participants with a positive SARS-CoV-2 PCR before D29 (n = 6), participants who showed signs of past SARS-CoV-2 infection based on baseline seropositivity for anti-S1 and/or anti-N IgG antibodies (n = 7), and two seronegative participants from the IM group who displayed activated SARS-CoV-2-spike-specific B-cells prior to vaccination, indicating recent infection.