An epidemiological survey of COVID-19 serology and its association with clinical infection among older adults– does antibody titer matter?

Table 2 Geometric mean antibody titer (GMAT) of anti-spike IgG antibodies among the study groups

All patients, n = 285	Hospitalized patients (n = 92)	Nursing home residents (n = 93)	Assisted-living carehome residents (n = 100)	p value
1st GMAT Au/ml (95% CI)	1307 (858–1992)	5292 (3949–7093)	10,398 (8085–13,373)	< 0.0001
2nd GMAT Au/ml (95% CI)^a	NA	3096 (2311–4148)	3738 (2899–4822)	0.68
Three-dose vaccine recipients^b	41/92 (45%)	70/93 (76%)	91/100 (100%)
1st GMAT Au/ml (95% CI) post 3rd vaccine	n = 41 3794 (2279–6319)	n = 70 6096 (4466–8321)	n = 91 11,367 (8845–14,608)	< 0.001
2nd GMAT Au/ml (95% CI) post 3rd vaccine^c	NA	n = 68/70 3280 (2390–4502)	n = 91/100 3661 (2840–4719)	0.48

^aNo data was available for hospitalized patients
^bCOVID19-recovered patients were excluded (NH residents n = 21, ALCH residents, n = 8). Two additional NH residents and one ALCH resident were vaccinated twice and therefore excluded
^cTwo NH residents died before testing

ISSN: 1471-2318