The SCOPE study assesses the prevalence of anti-SARS-CoV-2 antibodies among a representative sample of residents and staff in Belgian NH (nursing homes). Starting from February 1st 2021, a cohort of 1,640 residents and 1.368 staff members in 69 Belgian NHs are being tested every two months on the presence of anti-SARS-CoV-2 antibodies. This brief communication reports on the prevalence of anti-SARS-CoV-2 antibodies among vaccinated nursing home residents and staff. At the end of April 2021, the large scale vaccination campaign in Belgian nursing homes, which took place between January 5th and March 24th 2021, resulted in a vaccination coverage of 97% in NH residents and 84% in staff members. For these vaccinated groups, we describe the prevalence of anti-SARS-CoV-2 antibodies immediately following the vaccination campaign (April, 2021) and the seroprevalence evolution over the two following testing periods (in June and August 2021). Data collection of the August 2021 testing period was not finished at the time of compiling this brief communication. The August 2021 testing period comprises the data from 65 out of the 69 nursing homes. Additionally, some antibody test results are expected the coming weeks in case of self-sampling (for staff in particular). Results given here are preliminary. Small adaptations in some data might occur in future reports. ; SCOPE