Volume 27, Number 10—October 2021
Research
Direct and Indirect Effectiveness of mRNA Vaccination against Severe Acute Respiratory Syndrome Coronavirus 2 in Long-Term Care Facilities, Spain
Susana Monge
, Carmen Olmedo, Belén Alejos, María Fé Lapeña, María José Sierra1, Aurora Limia1, and COVID-19 Registries Study Group2
, Carmen Olmedo, Belén Alejos, María Fé Lapeña, María José Sierra1, Aurora Limia1, and COVID-19 Registries Study Group2
Table 1
Standardized risk, risk ratio, vaccine effectiveness, and risk difference in elderly residents of long-term care facilities with no evidence of previous severe acute respiratory syndrome coronavirus 2 infection, by time since first vaccinated, Spain, December 27, 2020–March 10, 2021*
| Time since vaccination |
Events/persons at risk |
Standardized risk† (95% CI) |
RR
(95% CI) |
VE, %
(95% CI) |
RD
(95% CI) |
|||
|---|---|---|---|---|---|---|---|---|
| Reference period |
Study period |
Unexposed |
Exposed |
|||||
| Effects in the vaccinated | ||||||||
| Full period | 19,244/258,357 | 10,785/230,195 | 12.8 (12.61–12.98) |
5.42 (5.32–5.52) |
0.43 (0.41–0.42) |
57.6 (56.6–58.6) |
−7.37 (−7.58 to −7.16) |
|
| 0–14 d | 5,355/258,357 | 5,957/230,195 | 20.92 (20.49–21.33) |
14.87 (14.56–15.16) |
0.73 (0.69–0.71) |
28.9 (26.9–31) |
−6.05 (−6.56 to −5.54) |
|
| 15–21 d | 2,966/246,924 | 2,690/218,621 | 22.34 (21.97–22.72) |
10.75 (10.55–10.95) |
0.49 (0.47–0.48) |
51.9 (50.7–53.1) |
−11.59 (−12.01 to −11.19) |
|
| 22–28 d | 3,234/239,409 | 1,253/212,421 | 18.43 (18.14–18.72) |
6.84 (6.67–7.0) |
0.38 (0.36–0.37) |
62.9 (61.9–64) |
−11.59 (−11.92 to −11.28) |
|
| >29 d‡ |
7,389/230,438 |
885/207,774 |
7.91 (7.73–8.09) |
1.44 (1.37–1.49) |
0.19 (0.17–0.18) |
81.8 (81.0–82.7) |
−6.47 (−6.66 to −6.28) |
|
| Indirect effects in the unvaccinated | ||||||||
| Full period | 271/2,713 | 117/2,254 | 17.16 (15.07–19.21) |
7.08 (5.79–8.35) |
0.41 (0.32–0.51) |
58.7 (49.4–68.5) |
−10.08 (−12.62 to −7.52) |
|
| 0–14 d | 70/2,713 | 59/2,254 | 20.87 (17.54–24.02) |
17.08 (13.68–20.48) |
0.82 (0.6–1.03) |
18.2 (−3.1 to 39.8) |
−3.79 (−8.54 to 1.14) |
|
| 15–21 d | 37/2,565 | 22/2,128 | 24.51 (21.37–27.52) |
13.48 (11.11–15.91) |
0.55 (0.43–0.67) |
45 (32.8–57.1) |
−11.02 (−14.88 to −6.99) |
|
| 22–28 d | 38/2,473 | 16/2,056 | 22.16 (19.34–24.93) |
9.35 (7.36–11.37) |
0.42 (0.32–0.53) |
57.8 (47.5–68.2) |
−12.81 (−16.16 to −9.39) |
|
| >29 d‡ | 126/2,350 | 20/1,997 | 14.09 (11.46–16.73) |
2.63 (1.58–3.62) |
0.19 (0.1–0.27) |
81.4 (73.3–90.3) |
−11.46 (−14.39 to −8.6) |
|
*Time since first vaccinated was a proxy of number of vaccine doses and days since last dose. RD, risk difference; RR, risk ratio; VE, vaccine effectiveness. †Per 10,000 population per day. ‡Full vaccination.
1These senior authors contributed equally to this article.
2Group members are listed at the end of this article.
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Page updated: September 19, 2021
Page reviewed: September 19, 2021
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