TABLE 2.
Characteristics of the residents with RT‐qPCR positive results during the SARS‐CoV‐2 B.1.1.7 outbreak
| Non‐vaccinated (a) (n = 21) | Vaccinated | p value | ||
|---|---|---|---|---|
| 1 vaccine dose (b) (n = 10) | 2 vaccine doses (c) (n = 72) | |||
| Age, mean (SD), year b | 90.3 (7.4) | 83.8 (8.4) | 89.1 (7.8) | .06 |
| Sex, n (%) d | ||||
| Female | 15 (71.4) | 8 (80.0) | 56 (77.8) | .87 |
| Male | 6 (28.6%) | 2 (20.0) | 16 (22.2) | |
| Charlson index (median, IQR) [range] b |
6 (6.0–8.0) [4–15] |
7.0 (5.0–8.0) 5–9 |
7.0 (6.0–8.0) 3–15 |
.96 |
| Prior SARS‐CoV−2‐positive RT‐qPCR, n (%) c | 1 (4.8) | 0 (0) | 3 (4.2) | 1.00 |
| First positive RT‐qPCR cycle threshold, median (IQR) d | 26.0 (23.0–32.0) | 24.85 (20.4; 28.0) | 24.00 (19.2; 28.6) | .74 |
| Cycle threshold of the second RT‐qPCR a , median (IQR) d | 30.3 (27–35.2) | 30.7 (23.1; 34.5) | 27.00 (21.0; 31.7) | .21 |
| Symptoms, n (%) c | .002 | |||
| Asymptomatic | 2 (9.5) | 6 (60.0) | 31 (43.7) | .01 (a vs b), |
| Mild | 4 (19.1) | 2 (20.0) | 23 (31.0) | .002 (a vs c) |
| Severe | 10 (47.6) | 0 | 15 (21.1) | .09 (b vs c) |
| Deaths, n (%) c | 5 (23.8) | 2 (20.0) | 3 (4.2) | .002 (a vs c) |
| SARS‐CoV‐2 IgG levels | n =10 | n =7 | n =49 | .29 |
| N‐protein IgG >0.8 signal to cutoff ratio, n (%) b | 2 (20.0) | 1 (14.3) | 4 (8) | |
| SARS‐RBD‐IgG (AU/ml) e |
.01 .01 (a vs c) |
|||
| <50 | 6 (60.0) | 1 (14.3) | 5 (10.2) | |
| 51–1050 | 3 (30.0) | 5 (71.4) | 22 (44.9) | |
| 1051–4160 | 0 (0) | 1 (14.3) | 15 (30.6) | |
| >4160 | 1 (10) | 0 (0) | 7 (14.3) | |
| Nucleocapide antigenemia titer b , median (IQR)[range] f |
n = 7 43.0 (2.9–150.2) [0.7–555.2) |
n =5 1.8 (0.5–3.0) [0.2–12.5] |
n =37 1.5 (−0.4–16–6) [−1.5–328–4] |
.03 .004 (a vs c) |
Analysis using Kruskal‐Wallis test.
Analysis using ANOVA.
Analysis using Fisher's exact test.
The second RT‐qPCR was performed 7 days after the first positive RT‐qPCR result in 47 residents.
Analysis using Mann‐Whitney test.
level of detection of the assay is 2.95 ng/ml. Samples with Nucleocapsid Ag level over 180 pg/ml were diluted. Titer is the number of dilutions possible, still reaching the detection threshold. According to the manufacturer of the SARS‐CoV‐2 IgG II Quant assay (Abbott Diagnostics), the positive threshold is of 50 AU/ml RBD‐IgG levels. check Based on previous studies, an RBD‐IgG level ≥1050 AU/ml is considered as a significant antibody response to the vaccine, 26 and a level ≥4160 AU/ml indicates a high neutralizing effect against SARS‐CoV‐2. 27