A total of 712 LTCF residents were included. The characteristics of the participants are summarized in Table 1. The median age was 81.3 years (IQR 74-89), with 518 individuals (72.8%) being female. The prevalence of frailty was 94.6% (27.7% CCF 6-7, 24.8% CCF 8 and 42.05% CCF 9-10). Cognitive impairment was observed in 79.9% of participants, while 69.5% exhibited mobility impairment, 78.3% presented with at least one chronic disease, and 72.7% reported the use of five or more medications per day, ranging from a minimum of 1 to a maximum of 17 drugs daily.
Table 1: Descriptive Statistics of Overall Study Population
Characteristic
|
n
|
%
|
Age
|
|
|
<70
|
86
|
12,1
|
70-79
|
222
|
31,22
|
80-89
|
244
|
34,32
|
90+
|
159
|
22,36
|
Sex
|
|
|
Female
|
518
|
72,86
|
Male
|
193
|
27,14
|
Race
|
|
|
White
|
238
|
37,01
|
Black
|
149
|
23,17
|
Pardo
|
256
|
39,81
|
CCF
|
|
|
Robust (1-3)
|
7
|
0,99
|
Risk of frail (4-5)
|
31
|
4,4
|
Frail 6-7
|
195
|
27,7
|
Frail 8
|
175
|
24,86
|
Frail 9-10
|
296
|
42,05
|
IVCF-20
|
|
|
Low Vulnerability (0-6)
|
58
|
8,43
|
Moderate Vulnerability (7-14)
|
112
|
16,28
|
High Vulnerability (15-40)
|
518
|
75,29
|
Polypharmacy
|
|
|
< 4 different drugs/day
|
153
|
27,27
|
≥ 5 different drugs/day
|
408
|
72,73
|
Comorbidities
|
|
|
Diabetes
|
148
|
24,07
|
Hypertension
|
415
|
67,48
|
Pulmonary disease
|
89
|
14,45
|
Cognitive impairment
|
491
|
79,97
|
Mobility impairment
|
443
|
69,54
|
The vaccination adherence was 99.5% of the cohort, all of whom received the complete three-dose regimen. In the first and second doses, 91.7% of the cohort received the ChAdOx1-S vaccine. In the third dose, 98.6% of the participants received the Comirnaty vaccine. Details regarding vaccine types are elaborated upon Supplementary Table 1.
The vaccination had a significant impact on the reduction in positive cases (p=.001), in admissions to emergency care (p<.001), hospitalization (p=.002) and deaths (p<.001). Prior to the vaccination, a total of 191 positive cases were documented, corresponding to 26.8% of the entire cohort. Among these contaminated individuals, 43.5% exhibited typical respiratory symptoms, 29.3% required emergency care or hospitalization, and 27 COVID-19 related deaths occurred, corresponding to a case fatality rate of 14.1%. After the first dose, 25 positive cases had occurred and after the second dose, 28 positive cases. Only six participants (24% of positive participants) were admitted to emergency care or hospital, after the first dose and six participants after the second dose. Two deaths were observed after both the first and second doses.
The period subsequent to the administration of the third dose coincided with the prevalence of the Omicron variant. During this period, the number of positive cases had arisen, with 136 positive cases, representing 19.2% of the cohort. Although, 85.3% were asymptomatic. Among the contaminated participants, 15 (11.1%) necessitated admission to emergency care or hospitalization. Five deaths have occurred, culminating in a post-vaccination case fatality rate of 3.8%, during the dominance of the Omicron variant. Details about vaccine effects are shown in Figure 1.
Figure 1. The number of positive cases, symptomatic participants, admission to emergency service, hospitalization and deaths, among LTCF residents, before the vaccine, and after the first, second and third vaccine doses. The red line corresponds to the proportion of positive cases in the general population.
When risk factors were analyzed (Figure 2), frailty, advanced age, presence of chronic diseases, cognitive impairment and polypharmacy were not associated with a higher rate of contamination by SARS-CoV-2. Mobility impairment, however, exhibited a significant correlation with a higher number of positive cases (p=.03) but not with typical symptoms and admission to emergency or hospital care.
Before the vaccination, individuals with a history of pulmonary disease (p=.03) and those dependent for BADL (p=.02) exhibited a higher prevalence of typical symptoms compared to other study participants. Furthermore, a significant association between dependence for BADL (p=.005), male sex (p=.02) and pulmonary disease (p=.008) was observed with a heightened number of admissions to emergency services and hospitalization (Figure 2).
In the non-vaccinated frail subgroup (CCF 8-10), 63 participants, which represents 48.4% of the positive cases exhibited typical symptoms and 45 participants (34.6%) necessitated emergency care or hospital admission. After the administration of three vaccine doses, the number of symptomatic patients in this group decreased to 16 (16.8%) and 12 participants (12.6%) needed admission, as depicted in Figure 2.
Prior to the vaccination, within the pulmonary disease group, 61.5% of the positive participants displayed typical respiratory symptoms and 50% required emergency care or hospital medical support. After the three doses, the number of symptomatic patients dwindled to 14.2%, with the same percentage necessitating medical intervention in this subgroup.
Male participants exhibited a higher frequency of hospitalization than females (p=.02). Pre-vaccination, 42% of male participants had been admitted to emergency care or hospital (Figure 2), compared to 24.8% of females. Following vaccination, admissions among males became comparable to those observed among females, with a comparable proportion of 13.5% of the positive cases in males and 15.1% in females, and no statistically significant difference between the two groups.
Age, hypertension, diabetes, cognitive impairment and polypharmacy did not exhibit significant associations with increased contamination rates, symptoms, admissions to emergency care and hospitalization.
Figure 2: The risk factors associated with a higher proportion of positive cases, symptomatic patients, and hospitalizations.
Table 2 compares the number of positive cases, symptomatic participants and participants requiring emergency or hospital care, before and after the three vaccine doses, across different risk factor subgroups. After the three vaccine doses, there was a significant reduction in the proportion of symptomatic patients and admissions, in almost all risk factor subgroups, with the exception of participants with diabetes, in which a reduction in the number of admissions occurred, although, was not statistically significant.
Table 2: Comparison between the number of positive cases, symptomatic participants and participants who need emergency or hospital care, before and after the three vaccine doses, in different subgroups of risk factors.
|
Characteristics
|
Positive cases
|
Symptoms
|
Admission
|
|
Before
|
After
|
|
Before
|
After
|
|
Before
|
After
|
|
|
N
|
%
|
N
|
%
|
p
|
N
|
%
|
N
|
%
|
p
|
N
|
%
|
N
|
%
|
p
|
Age ≥ 80
|
119
|
31
|
74
|
27
|
0.3
|
51
|
43
|
14
|
18
|
<0.001
|
34
|
28
|
10
|
13
|
0.01
|
CCF 8-10
|
130
|
31
|
94
|
29
|
0.6
|
63
|
48
|
16
|
16
|
<0.001
|
45
|
34
|
12
|
12
|
<0.001
|
IVCF-20 ≥ 15
|
139
|
30
|
99
|
28
|
0.6
|
61
|
44
|
15
|
15
|
<0.001
|
41
|
29
|
13
|
13
|
0.002
|
Male
|
49
|
30
|
37
|
25
|
0.3
|
25
|
50
|
5
|
13
|
<0.001
|
21
|
42
|
4
|
10
|
0.001
|
Cognitive impairment
|
142
|
30
|
93
|
27
|
0.2
|
64
|
45
|
12
|
12
|
<0.001
|
43
|
30
|
9
|
9
|
<0.001
|
Mobility impairment
|
116
|
27
|
89
|
30
|
0.4
|
53
|
45
|
13
|
14
|
<0.001
|
38
|
32
|
11
|
12
|
<0.001
|
Diabetes
|
42
|
31
|
26
|
26
|
0.4
|
17
|
40
|
3
|
11
|
0.008
|
12
|
28
|
3
|
11
|
0.8
|
Hypertension
|
112
|
28
|
73
|
25
|
0.4
|
47
|
42
|
13
|
17
|
<0.001
|
32
|
28
|
9
|
12
|
0.007
|
Pulmonary disease
|
25
|
29
|
14
|
24
|
0.5
|
16
|
61
|
2
|
14
|
0.004
|
13
|
50
|
2
|
14
|
0.02
|
Polypharmacy
|
125
|
32
|
63
|
23
|
0.01
|
55
|
44
|
11
|
17
|
<0.001
|
40
|
32
|
9
|
14
|
0.007
|
When the number of positive cases was evaluated in association with LTC characteristics (Figure 3), we observed a trend indicating higher proportions of positive cases in LTCFs with larger resident populations. The number of cases was significantly lower in LTC with a smaller number of residents, in contrast to LTCF with more than 20 residents (p=.002).
Figure 3. Correlation between the number of residents in each LTCF and the proportion of positive cases.