This implies that vaccine\derived SARS\CoV\2\specific memory function remains and elicits an adequate response at the time of 6 months after the third vaccination. dose (24,026.3 vs. 30,328.6?AU/mL, (range)48.7??13.6 (27C70)47.0??11.0 (21C65)84.5??6.6 (68C94)84.2??9.9 (62C100)Chronic underlying diseaseNo disease22 (88.0)28 (84.9)0 (0.0)0 (0.0)Dementia0 (0.0)0 (0.0)35 (100.0)18 (94.7)HDS\R (0C30)a, mean scoresN/AN/A4.06.0Hypertension2 (8.0)3 (9.1)9 (25.7)5 (26.3)Cardiac disease1 (4.0)0 (0.0)5 (14.3)2 (10.5)Chronic pulmonary disease0 (0.0)2 (6.1)4 (11.4)1 (5.3)Renal disease0 (0.0)0 (0.0)3 (8.6)0 (13.3)Cerebrovascular disease0 (0.0)0 (0.0)5 (14.3)6 (31.6)Diabetes0 (0.0)2 (6.1)4 (11.4)3 (15.8)Time from vaccination to sample collection,mean days??(range)Scheduled 21 days after the third dose21.1??1.24 (19C23)20.8??1.16 (18C24)20.4??0.50 (20C21)20.4??1.42 (15C21)Scheduled 5 months after the third dose155.6??4.37 (149C168)158.9??3.72 (154C169)149.1??6.69 (140C166)150.3??7.07 (143C165)Scheduled 21 days after the fourth dose19.9??0.46 (19C21)20.5??1.89 (18C25)19.2??0.83 (19C21)20.1??0.72 (19C21)Time between the third and fourth doses,189.8??23.53 (157C221)202.0??16.09 (161C225)168.6??8.17 (163C189)173.0??9.2 (151C187)mean days??(range) Open in a separate window values of <.05 were considered statistically significant. All statistical analyses were performed using JMP Pro, version 14 (SAS Institute, Inc.). 3.?RESULTS A total of 112 individuals, including 58 healthcare workers (mean age: 47.7 years; 25 SARS\CoV\2\naive and 33 previously infected) and 54 nursing home residents (mean age: 84.4 years; 35 SARS\CoV\2\naive and 19 previously infected) were eligible for the study. Based on antispike and antinucleocapsid antibody testing, none of the SARS\CoV\2\naive healthcare workers or residents were recategorized as previously infected. The baseline clinical characteristics of the 112 individuals are shown in Table?1. No individuals received immunosuppressant CTEP treatment, except for a previously infected healthcare worker with steroid treatment. All durations from vaccination to sample collection were comparable among the healthcare workers and residents. The periods between the third and fourth doses were also comparable, at approximately 6 months. Figure?1 shows the antispike IgG antibody levels shortly and 5 months after the third dose and shortly after the fourth dose. The median IgG level in SARS\CoV\2\naive residents 5 months after the third dose was approximately twofold lower than that in SARS\CoV\2\naive healthcare workers, with the lowest levels among the four groups. However, the frequency of IgG levels of 4160?AU/mL in the residents 5 months after the third dose was almost 50% (48.6%, 17/35), in contrast to 6 months after the second dose. 8 The threshold of antispike IgG levels of 4160?AU/mL corresponded to a 0.95 probability of obtaining a PRNT ID50 at a 1:250 dilution. The median CTEP IgG level after the fourth dose in SARS\CoV\2\naive residents appeared to be lower than that in SARS\CoV\2\naive healthcare workers, but this difference was not statistically significant (24,026.3 vs. 30,328.6?AU/mL, p?=?.79). As a result, the IgG CTEP levels after the fourth dose in SARS\CoV\2\naive residents reached a comparable level of healthcare workers, from approximately half the level after the third dose. IgG levels in previously infected residents seemed not to decrease at a time of 5 months after the third dose, in contrast to SARS\CoV\2\naive residents. The median IgG level in previously infected residents after the fourth dose was the highest among the four groups. Basic data around the antibody levels are shown in Table?S1. Open in a separate window Physique 1 Antispike (RBD) IgG antibody levels shortly after CTEP the third dose, 5 months after the third dose, and shortly after the fourth dose of wild\type SARS\CoV\2 mRNA vaccination in SARS\CoV\2\naive CTEP and previously infected healthcare workers and nursing home residents. The white circles indicate data of SARS\CoV\2\naive healthcare workers (n?=?25). The white Rabbit Polyclonal to OR2AP1 triangles indicate data of previously infected healthcare workers (n?=?33). The black circles indicate data of SARS\CoV\2\naive residents (n?=?35). The black triangles indicate data of previously infected residents (n?=?19). After doses 3 and 4 indicate 21 days after each dose. Five months indicate 5 months after the third dose. The horizontal solid bars and numbers in each group indicate the median values. The horizontal line indicates the value of 4160?AU/mL,.