Table 1.

Overview of studies using SARS-CoV-2 genome sequencing of samples taken for routine surveillance or during investigation of outbreaks in LTCFs

	Location	Start and end date of study (in 2020)	Type of study*	Number of LTCFs	Total number of residents and staff tested	Number of residents testing positive	Number of staff testing positive	Cases sequenced	Number of clusters†
Dautzenberg et al (2020)16‡	Southeast Netherlands	March–April	Surveillance	2	621	NR	133	22	3
van den Besselaar et al (2021)17	South Holland	May–June	Outbreak	1	425	113	56	60§	1
Hamilton et al (2021)18	East of England, UK	February–May	Surveillance	292	6600	1167	NR	700	409
Page et al (2021)19	Norfolk, UK	March–August	Surveillance	6	1035	76	9 and 3¶	89	2
Graham et al (2020)20	London, UK	April	Outbreak	4	383	126	3	19‖	NR
Ladhani et al (2020)21 and Ladhani et al (2020)22	London, UK	April	Outbreak	6	518	105	53	99	2
Lemieux et al (2020)23	Boston, MA, USA	January–May	Surveillance	1	194	82	36	83	3
Zhang et al (2020)24	CA, USA	March–April	Surveillance	2	10	6 and 1**	3	192	1
Gallichote et al (2020)25‡	CO, USA	Unknown	Surveillance	5	454	NR	70	38	1
Taylor et al (2020)26	MN, USA	April–June	Outbreak	2	600	165	114	105	4
Arons et al (2020)27	WA, USA	March	Outbreak	1	89	57	26	34	2

LTCFs=long-term care facilities. NR=not reported.

^*Surveillance studies are defined as those which involve serial testing to identify positive cases, and outbreak investigations are those which involve the testing or sequencing, or both, of positivity after a case (or a defined number of cases) of SARS-CoV-2 have been identified.

^†Clusters are not uniformly defined in all papers.

^‡Preprint before peer review.

^§Six of these samples were from an epidemiologically linked hospital outbreak.

^¶Family members of a single staff member.

^‖Paper states both 17 and 19 samples sequenced, so it is not clear which is correct.

^**Family member of resident.