Table 2.
Characteristics of Post-Vaccine Severe Acute Respiratory Syndrome Coronavirus 2 Cases Among Healthcare Personnel
| Variable | Total, N = 189 | No Mutation Identified (Wild-Type), N = 70a (62.5%) | L452R (Presumptive B.1.427/B.1.429), N = 42a (37.5%) | P Value |
|---|---|---|---|---|
| Age, years | ||||
| Mean (SD) | 40.8 (11.2) | 42.5 (11.6) | 40.8 (10.1) | .424 |
| Median (IQR) | 38 (32–48) | |||
| Sex | ||||
| Male | 64 (33.9%) | 18 (25.7%) | 13 (31.0%) | .549 |
| Female | 125 (66.1%) | 52 (74.3%) | 29 (69.0%) | |
| Professional roleb | ||||
| Patient facing | 129 (68.3%) | 45 (66.2%) | 31 (73.8%) | .400 |
| Non-patient facing | 55 (29.1%) | 23 (33.8%) | 11 (26.2%) | |
| Unknown | 5 (2.6%) | |||
| Immunocompromised | ||||
| Yes | 7 (3.7%) | 3 (4.5%) | 2 (5.4%) | .846 |
| No | 166 (87.8%) | 63 (95.5%) | 35 (94.6%) | |
| Unknown | 16 (8.5%) | |||
| Tested positive after second vaccine dose | ||||
| Yes | 39 (20.6%) | 10 (14.3%) | 14 (33.3%) | .017 |
| No | 150 (79.4%) | 60 (85.7%) | 28 (66.7%) | |
| Days from dose 1 to symptom onset (n = 151)c | ||||
| Mean (SD) | 16.8 (23.3) | 11.6 (17.4)c1 | 24.2 (29.0)c2 | .008 |
| Median (IQR) | 8 (3–18) | |||
| Days from dose 1 to positive NAAT | ||||
| Mean (SD) | 19.4 (22.0) | 14.7 (17.7) | 25.8 (28.0) | .011 |
| Median (IQR) | 11 (7–22) | |||
| Days from dose 2 to symptom onset (n = 31)d | ||||
| Mean (SD) | 30.0 (27.8) | 25.0 (22.0)d1 | 36.6 (32.0)d2 | .350 |
| Median (IQR) | 24 (4-60) | |||
| Days from dose 2 to positive NAAT (n = 39)e | ||||
| Mean (SD) | 31.3 (25.5) | 29.6 (22.2)e1 | 35.5 (28.2)e2 | .573 |
| Median (IQR) | 24 (7-55) | |||
| Vaccination status at time of positive NAAT | ||||
| Early post-vaccination | 114 (60.3%) | 52 (74.3%) | 22 (52.4%) | .020f |
| Partially vaccinated | 49 (25.9%) | 11 (15.7%) | 10 (23.8%) | |
| Fully vaccinated | 26 (13.8%) | 7 (10.0%) | 10 (23.8%) | |
| Vaccine brand | ||||
| Pfizer | 173 (91.5%) | 66 (94.3%) | 39 (92.9%) | .762 |
| Moderna | 15 (7.9%) | 4 (5.7%) | 3 (7.1%) | |
| Unknown | 1 (0.5%) | |||
| Cycle threshold value (n = 101)g | ||||
| Mean (SD) | 24.9 (8.0) | 21.1 (4.5)g1 | 19.3 (4.4)g2 | .133 |
| Median (IQR) | 22 (17–31) | |||
| Experienced SARS-CoV-2 symptoms | ||||
| Yes | 157 (83.1%) | 63 (92.6%) | 38 (95.0%) | .631 |
| No | 26 (13.8%) | 5 (7.4%) | 2 (5.0%) | |
| Unknown | 6 (3.2%) | |||
| Household contact | ||||
| Yes | 79 (41.8%) | 32 (50.0%) | 21 (55.3%) | .607 |
| No | 94 (49.7%) | 32 (50.0%) | 17 (44.7%) | |
| Unknown | 16 (8.5%) | |||
| Previously positive for SARS-CoV-2 | ||||
| Yes | 4 (2.1%) | 2 (3.1%) | 0 | .533 |
| No | 167 (88.4%) | 63 (96.9%) | 37 (100%) | |
| Unknown | 18 (9.5%) |
Abbreviations: IQR, interquartile range; NAAT, nucleic acid amplification test; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2; SD, standard deviation.
aMutation data available for n = 115 post-vaccine SARS-CoV-2 cases (PVSCs); 70 with no mutation, 42 with isolated L452R mutation presumptive of B.1.427/B.1.429 variant, and 3 with isolated N501Y mutation. Only samples with L452R and no other mutations are compared here due to few N501Y mutations. Mutation data not available for n = 32 with cycle threshold (Ct) values not meeting criteria, n = 27 with SARS-CoV-2 test done outside Stanford Health Care system, n = 15 with samples otherwise not available for mutation testing.
bPatient-facing roles = physician/physician assistant/nurse practitioner (n = 22, 11.7%), nursing (n = 42, 22.2%), medical assistant (n = 17, 9.0%), respiratory therapy/physical therapy/occupational therapy (n = 5, 2.6%), other (n = 43, 22.8%). Non-patient facing roles = housekeeping/food services (n = 22, 11.7%); other (33, 17.4%).
cn = 151 includes symptomatic PVSCs with known date of symptom onset; c1n = 62; c2n = 37.
dn = 31 includes symptomatic PVSCs who tested positive after dose 2 and had known date of symptom onset; d1n = 9; d2n = 11.
en = 39 includes all PVSCs who tested positive after dose 2; e1n = 10; e2n = 14.
f P value reflects extended Mantel-Haenszel χ2 for linear trend, univariate analysis unadjusted for rising prevalence of B.1.427/B.1.429 from December 2020 to March 2021.
gCt values not available for individuals tested outside the Stanford Health Care system or by transcription-mediated amplification; only samples with Ct<30 (before 1 March 2021) or Ct<34 (after 1 March 2021) included in variant analysis; g1n = 45; g2n = 19.