Repeated COVID-19 mRNA vaccination results in IgG4 class switching and decreased NK cell activation by S1-specific antibodies in older adults. - Gelderloos, Anne T.; Verheul, Marije K.; Middelhof, Irene; de Zeeuw-Brouwer, Mary-Lène; van Binnendijk, Robert S.; Buisman, Anne-Marie; van Kasteren, Puck B. (Immunity & Ageing, 2024)