Vaccine effectiveness against SARS-CoV-2 transmission to household contacts during dominance of Delta variant (B.1.617.2), the Netherlands, August to September 2021. - de Gier B; Andeweg S; Backer JA; Hahné SJ; van den Hof S; de Melker HE; Knol MJ (Euro surveillance : bulletin Europeen sur les maladies transmissibles = European communicable disease bulletin, 2021)