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Volume 28, Number 10—October 2022
Research Letter

Effectiveness of Booster and Influenza Vaccines against COVID-19 among Healthcare Workers, Taiwan

Jun Yi Sim, Ping-Sheng Wu, Ching-Feng Cheng, You-Chen Chao, and Chun-Hsien YuComments to Author 
Author affiliation: Taipei Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Taipei, Taiwan; and Tzu Chi University, Hualien, Taiwan

Main Article

Table

Characteristics of 2,196 healthcare workers tested for SARS-CoV-2 after receiving COVID-19 booster and influenza vaccines, Taipei Tzu Chi Hospital, Taipei, Taiwan*

Characteristics Regular testing, n = 343†
Symptom-triggered testing, n = 1,853
Positive, no. (%) Negative, no. (%) p value OR (95% CI) Positive, no. (%) Negative or no symptom, no. (%) p value OR (95% CI)
Total
93 (100)
250 (100)
NA
NA

360 (100)
1,493 (100)
NA
NA
Sex 0.051 0.084
F 67 (72.0) 205 (82.0) NA 1.4 (0.7–3.1) 278 (77.2) 1,085 (72.7) NA 1.0 (0.7–1.4)
M
26 (28.0)
45 (18.0)
NA
Referent

82 (22.8)
408 (27.3)
NA
Referent
Age range, y 0.377 0.345
71–80 1 (1.1) 0 NA NA 1 (0.3) 8 (0.5) NA 0.7 (0.1–6.0)
61–70 1 (1.1) 4 (1.6) NA 0.7 (0.1–6.6) 6 (1.7) 55 (3.7) NA 0.5 (0.2–1.3)
51–60 3 (3.2) 18 (7.2) NA 0.5 (0.1–2.0) 33 (9.2) 160 (10.7) NA 0.9 (0.6–1.3)
41–50 15 (16.1) 39 (15.6) NA 0.9 (0.4–1.9) 93 (25.8) 362 (24.2) NA 1.0 (0.7–1.4)
31–40 29 (31.2) 63 (25.2) NA 1.1 (0.6–2.1) 92 (25.6) 391 (26.2) NA 1.0 (0.7–1.3)
21–30
44 (47.3)
126 (50.4)
NA
Referent

135 (37.5)
517 (34.6)
NA
Referent
Work sector <0.001 <0.001
Nursing 52 (55.9) 175 (70.0) NA 0.1 (0.1–0.4) 170 (47.2) 641 (42.9) NA 0.9 (0.6–1.2)
Medical 15 (11.3) 37 (14.8) NA 0.2 (0.1–0.5) 39 (10.8) 309 (20.7) NA 0.5 (0.3–0.8)
Technical 6 (6.5) 9 (3.6) NA 0.3 (0.1–1.1) 43 (11.9) 197 (13.2) NA 0.8 (0.5–1.2)
Laboratory, pharmacy 3 (3.2) 20 (8.0) NA 0.1 (0.0–0.3) 32 (8.9) 100 (6.7) NA 1.1 (0.7–1.8)
Housekeeping 0 2 (0.8) NA NA 6 (1.7) 9 (0.6) NA 2.8 (0.9–8.6)
Administration
17 (18.3)
7 (2.8)
NA
Referent

70 (19.4)
237 (15.9)
NA
Referent
No. COVID-19 vaccine doses 0.065 <0.001
3 88 (94.6) 246 (98.4) NA 0.2 (0.0–0.8) 319 (88.6) 1,416 (94.8) NA 0.4 (0.2–0.6)
2 5 (5.4) 4 (1.6) NA Referent 38 (10.6) 73 (4.9) NA Referent
1 0 0 NA NA 0 0 NA NA
0
0
0
NA
NA

3 (0.8)
4 (0.3)
NA
NA
COVID-19 primary series‡ 0.442 0.348
Viral vector + viral vector 70 (75.3) 193 (77.2) NA NA 270 (75.0) 1,091 (73.1) NA NA
Viral vector + mRNA 7 (7.5) 27 (10.8) NA NA 45 (12.5) 189 (12.7) NA NA
mRNA + mRNA 15 (16.1) 30 (12.0) NA NA 41 (11.4) 206 (13.8) NA NA
Protein subunit + protein subunit
0
0
NA
NA

0
2 (0.1)
NA
NA
COVID-19 booster§ 1.00 0.145
mRNA 86 (92.5) 243 (97.2) NA NA 317 (88.1) 1,387 (92.9) NA NA
Protein subunit
0
2 (0.8)
NA
NA

2 (0.5)
27 (1.8)
NA
NA
Booster vaccine date¶ 0.111 <0.001
December 2021 23 (24.7) 68 (27.2) NA NA 70 (19.4) 319 (21.4) NA NA
January 2022 55 (59.1) 164 (65.6) NA NA 219 (60.8) 999 (66.9) NA NA
February 2022 4 (4.3) 4 (1.6) NA NA 17 (4.7) 35 (2.3) NA NA
March 2022 3 (3.2) 7 (2.8) NA NA 5 (1.4) 32 (2.1) NA NA
April 2022 0 3 (1.2) NA NA 6 (1.7) 24 (1.6) NA NA
May 2022
1 (1.1)
0
NA
NA

0
4 (0.3)
NA
NA
Tetravalent influenza vaccine, 2021–22 season 0.297 0.016
Vaccinated 68 (73.1) 167 (66.8) NA 1.5 (0.8–2.7) 265 (73.6) 1,001 (67.0) NA 1.5 (1.1–2.0)
Not vaccinated 25 (26.9) 83 (33.2) NA Referent 95 (26.4) 492 (33.0) NA Referent

*p values calculated by using χ2 test; OR and 95% CI calculated by using multinomial logistic regression. NA, not applicable; OR, odds ratio. †For age 71–80 y and housekeepers of the regularly tested subgroup, estimates were not shown because the groups were too small. ‡Excluding 7 unvaccinated workers and 3 workers who did not report vaccine type. Data available for a total of 2,186 healthcare workers; regular testing subgroup included 92 positive cases and 250 negative cases; symptom-triggered testing subgroup included 356 positive cases and 1,488 negative cases; thus, percentages do not add up to 100%. §Excluding 7 unvaccinated workers, 120 workers who did not receive a booster vaccine, and 5 workers who did not report booster vaccine type. Data available for a total of 2,064 healthcare workers; regular testing subgroup included 86 positive cases and 245 negative cases; symptom-triggered testing subgroup included 319 positive cases and 1,414 negative cases; thus, percentages do not add up to 100%. ¶Excluding 7 unvaccinated workers, 120 workers who did not receive a booster vaccine, and 7 workers who did not report month of booster vaccine. Data available for a total of 2,062 healthcare workers; regular testing subgroup included 86 positive cases and 246 negative cases; symptom-triggered testing subgroup included 317 positive cases and 1,413 negative cases; thus, percentages do not add up to 100%.

Main Article

Page created: August 12, 2022
Page updated: September 21, 2022
Page reviewed: September 21, 2022
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