Clinical characteristics and outcomes of healthcare workers with COVID-19 pre- and postvaccination
Abstract
Vaccines are the most effective strategy to control the spread of coronavirus disease-2019 (COVID-19). Data on COVID-19 among healthcare workers (HCW) pre- and postvaccination are limited. This study aims to evaluate the clinical characteristics and outcomes of HCW with COVID-19 pre- and postvaccination. Retrospective cohort study. All HCWs with suspected COVID-19 were included. Demographic data, occupation, symptoms, work in COVID-19 area, and vaccination status were collected. There were 22 267 HCW visits for suspected COVID-19; 7879 (35.4%) tested positive, and 14 388 (64.6%) tested negative. Fever, cough, fatigue, and dyspnea were positive predictors of COVID-19, and sore throat, headache, coryza, work in a COVID-19 area, and COVID-19 vaccination were negative predictors. Of the total number of visits, 41.2% were from vaccinated HCW and 58.8% were from unvaccinated HCW. Among HCWs with COVID-19, 84 (1.1%) required hospitalization, 11 (0.1%) in an intensive care unit (ICU), with three (0.04%) deaths. Six hospitalizations occurred in vaccinated HCWs, being of short duration, with no need for ICU admission and no deaths. SARS-CoV-2 infection prevalence was high among HCW, and vaccinated HCW had fewer hospitalizations, need for ICU, and deaths. Therefore, vaccines may attenuate COVID-19 severity, and efforts must be concentrated to ensure adequate vaccination for HCW.
1 INTRODUCTION
Coronavirus disease-2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has spread worldwide since December 2019, causing significant morbidity and mortality. Healthcare workers (HCW) are at higher risk of exposure to SARS-CoV-2 and can be vectors of the disease, transmitting it to patients and accelerating its spread.1 Early pandemic studies have shown a prevalence of SARS-CoV-2 infection in HCW ranging from 7% to 11%.2, 3 This prevalence was comparable between frontline and nonfrontline HCW.4, 5 One study6 showed that most HCWs were not hospitalized, and deaths occurred most frequently among those aged ≥65 years. However, another study7 conducted at the beginning of the pandemic with 438 HCW showed that 27.5% were admitted to an intensive care unit (ICU), 15.8% required invasive mechanical ventilation, and 4.2% died during hospitalization.
So far during the pandemic, vaccines are the most effective strategy to control the spread of SARS-CoV-2 infection. Among vaccinated patients, the risk of hospitalization, mechanical ventilation, or death for COVID-19 was significantly decreased.8, 9 Data on COVID-19 among HCW pre- and postvaccination are limited,10-12 and none are available for Brazil, which has one of the highest death tolls worldwide.13 Therefore, this study aims to evaluate the clinical characteristics and outcomes of HCW with COVID-19 pre- and postvaccination.
2 METHODS
2.1 Study design and location
We conducted a retrospective cohort study in a general, tertiary care, university-affiliated hospital. Ethics approval was obtained from the Ethics Committee of Hospital de Clínicas de Porto Alegre in September 14, 2020 (number 200459) along with a waiver of written informed consent.
2.2 Patients and data collection
Data were retrieved from the hospital information system database. All HCWs with suspected COVID-19 from March 2020 to January 2022 were included in the study. Some HCWs were included more than once as all visits for COVID-19 symptoms were considered. We considered a confirmed case of COVID-19 if an reverse transcription-polymerase chain reaction (RT-PCR) test for SARS-CoV-2 infection was detected.
The following data were collected from hospital charts in a standardized questionnaire: demographic data (sex and age), occupation (physician, nurse, nursing technician, laboratory personnel, physical therapist, administrative personnel, and others), symptoms, work in COVID-19 area, and vaccination status. We considered vaccinated those HCWs with at least two doses of any COVID-19 vaccine.
2.3 Statistical analyses
Data analysis was performed using SPSS 18.0 (Statistical Package for the Social Sciences). Data were presented as a number of cases, mean ± standard deviation (SD), or median with interquartile range (IQR). Categorical comparisons were performed by Pearson's Chi-square test. Continuous variables were compared using analysis of variance (ANOVA). Multivariate logistic regression analysis was performed to assess factors associated with the COVID-19 diagnosis and the symptoms related to COVID-19 in vaccinated and unvaccinated HCW. Hierarchical logistic regression models with predictors added one at a time were examined to assess possible collinearity between the predictors. The predictors selected in the final model were based on numerical and clinical significance. The quality of fit of the multiple logistic regression models was evaluated with the Hosmer–Lemeshow test. Odds ratios (ORs) and 95% confidence intervals (CI) were presented. A two-sided pvalue < 0.05 was considered significant for all analyses.
A previous study10 that found a prevalence of COVID-19 of 2.3% among partially vaccinated and 10.1% among unvaccinated was used to calculate the sample size. Thus, considering an alpha error of 5% and a study power of 80%, it would be necessary to include at least 146 patients in each group.
3 RESULTS
During the study period, there were 22 267 HCW visits for suspected COVID-19; 7879 (35.4%) tested positive for SARS-CoV-2 infection, and 14 388 (64.6%) tested negative for SARS-CoV-2 infection. Table 1 describes the factors associated with COVID-19 diagnosis in HCW. Working in the COVID-19 area was more frequent in the COVID-19 negative group than in the COVID-19 positive group (18.0% vs. 13.7%; p < 0.0001). A positive test for COVID-19 was less common in COVID-19 vaccinated HCW than in unvaccinated ones (28.9% vs. 47.8%; p < 0.0001). Fever, cough, fatigue, and dyspnea were more frequent among COVID-19 positive HCW (p < 0.0001 for all). On the other hand, sore throat, headache, and coryza were more common among COVID-19 negative HCW (p < 0.0001 for all). In a multivariate analysis, fever, cough, fatigue, and dyspnea were positive predictors of COVID-19 diagnosis; also, sore throat, headache, coryza, work in a COVID-19 area, and COVID-19 vaccination were negative predictors of COVID-19 diagnosis (Table 2).
| Characteristics | COVID-19+ n = 7879 | COVID-19– n = 14388 | p Value |
|---|---|---|---|
| Age, years | 41.6 ± 10.4 | 41.6 ± 10.5 | 0.663 |
| Male sex | 2766 (35.1) | 5022 (34.9) | 0.784 |
| HCW | |||
| Physicians | 644 (8.2) | 1836 (12.8) | <0.0001 |
| Nurses | 339 (4.3) | 995 (6.9) | <0.0001 |
| Nursing technician | 1322 (16.8) | 3365 (23.4) | <0.0001 |
| Physical therapist | 67 (0.9) | 238 (1.7) | <0.0001 |
| Laboratory personnel | 44 (0.6) | 166 (1.2) | <0.0001 |
| Administrative personnel | 205 (2.6) | 620 (4.3) | <0.0001 |
| Others | 5269 (66.9) | 7208 (50.1) | <0.0001 |
| Work in COVID-19 area | 1080 (13.7) | 2586 (18.0) | <0.0001 |
| Symptoms | |||
| Fever | 1314 (16.7) | 1647 (11.4) | <0.0001 |
| Cough | 3707 (47.0) | 6002 (41.7) | <0.0001 |
| Sore throat | 2102 (26.7) | 6976 (48.5) | <0.0001 |
| Fatigue | 3073 (39.0) | 4191 (29.1) | <0.0001 |
| Dyspnea | 653 (8.3) | 740 (5.1) | <0.0001 |
| Headache | 3391 (43.0) | 7526 (52.3) | <0.0001 |
| Coryza | 2395 (30.4) | 6711 (46.6) | <0.0001 |
| COVID-19 vaccinated | 2280 (28.9) | 6884 (47.8) | <0.0001 |
- Abbreviations: COVID-19, coronavirus disease-2019; HCW, healthcare worker.
| Characteristic | β | SE | Wald | OR (95% CI) | p Value |
|---|---|---|---|---|---|
| Fever | 0.563 | 0.044 | 164.306 | 1.756 (1.611–1.913) | <0.0001 |
| Cough | 0.501 | 0.033 | 235.748 | 1.651 (1.549–1.760) | <0.0001 |
| Sore throat | −0.871 | 0.033 | 679.762 | 0.419 (0.392–0.447) | <0.0001 |
| Fatigue | 0.509 | 0.033 | 230.679 | 1.663 (1.557–1.776) | <0.0001 |
| Dyspnea | 0.131 | 0.061 | 4.599 | 1.140 (1.011–1.285) | 0.032 |
| Headache | −0.272 | 0.032 | 70.277 | 0.762 (0.715–0.812) | <0.0001 |
| Coryza | −0.531 | 0.034 | 245.771 | 0.588 (0.550–0.629) | <0.0001 |
| COVID-19 vaccinated | −0.675 | 0.032 | 453.616 | 0.509 (0.479–0.542) | <0.0001 |
| Work in COVID-19 area | −0.170 | 0.042 | 16.531 | 0.844 (0.777–0.916) | <0.0001 |
- Abbreviations: CI, confidence interval; COVID-19, coronavirus disease-2019; HCW, healthcare worker; OR, odds ratio; SE, standard error.
Of the total number of visits, 9164 (41.2%) were from vaccinated HCW and 13 103 (58.8%) were from unvaccinated HCW. Among HCW with COVID-19, 84 (1.1%) required hospitalization, 11 (0.1%) of which were in an intensive care unit (ICU), with three (0.04%) deaths. Only six hospitalizations occurred in vaccinated HCW, being of short duration (length of hospital stay range: 1–7 days), with no need for ICU admission and no deaths (p < 0.0001 for the comparison with unvaccinated HCW). Table 3 shows the symptoms of COVID-19 according to vaccination status in HCW. Dyspnea and fatigue were less frequent among vaccinated HCW, while the other symptoms were more common (p < 0.0001 for all). In a multivariate analysis, fever, sore throat, and coryza were positive predictors of COVID-19 among vaccinated HCW; on the other hand, fatigue and dyspnea were negative predictors of COVID-19 among vaccinated HCW (Table 4).
| Symptoms | COVID-19 vaccinated | COVID-19 unvaccinated | p Value |
|---|---|---|---|
| Fever | 456 (20.0) | 858 (15.3) | <0.0001 |
| Cough | 1187 (52.1) | 2520 (45.0) | <0.0001 |
| Sore throat | 858 (37.6) | 1244 (22.2) | <0.0001 |
| Fatigue | 791 (34.7) | 2282 (40.8) | <0.0001 |
| Dyspnea | 123 (5.4) | 530 (9.5) | <0.0001 |
| Headache | 1126 (49.4) | 2265 (40.5) | <0.0001 |
| Coryza | 946 (41.5) | 1449 (25.9) | <0.0001 |
- Abbreviations: COVID-19, coronavirus disease-2019; HCW, healthcare worker.
| Symptom | β | SE | Wald | OR (95% CI) | p Value |
|---|---|---|---|---|---|
| Fever | 0.220 | 0.068 | 10.587 | 1.246 (1.091–1.422) | 0.001 |
| Sore throat | 0.576 | 0.058 | 98.472 | 1.778 (1.587–1.993) | <0.0001 |
| Fatigue | −0.361 | 0.055 | 43.002 | 0.697 (0.625–0.776) | <0.0001 |
| Dyspnea | −0.510 | 0.107 | 22.581 | 0.601 (0.487–0.741) | <0.0001 |
| Coryza | 0.567 | 0.056 | 101.630 | 1.764 (1.579–1.969) | <0.0001 |
- Abbreviations: CI, confidence interval; COVID-19, coronavirus disease-2019; OR, odds ratio; SE, standard error.
4 DISCUSSION
This study found a high prevalence (35.4%) of SARS-CoV-2 infection among HCWs seeking care for suspected COVID-19. In addition, COVID-19 vaccination was a negative predictor of COVID-19 diagnosis, and was associated with fewer hospitalizations, need for ICU, and deaths.
In fact, it has been demonstrated that COVID-19 vaccines help protect against severe illness, hospitalization, and death. The incidence of asymptomatic infection has also been shown to be reduced. In addition, breakthrough infections (infections in fully vaccinated people) are associated with few symptoms.12 However, a few studies evaluated the proportion of COVID-19 infections in vaccinated and unvaccinated HCW. Chandan et al.10 found a prevalence of SARS-CoV-2 infection among fully vaccinated, partially vaccinated, and unvaccinated HCWs of 1.3%, 2.3%, and 10.1%, respectively. In the first year of the pandemic, the estimated prevalence of SARS-CoV-2 infection from RT-PCR samples from HCW was 11% in one meta-analysis.3 Later in 2021, another meta-analysis14 found that the percentage of HCW who tested positive for COVID-19 was 51.7%. In our study, the overall prevalence of SARS-CoV-2 infection was 35.4%; however, we evaluated data from the pandemics beginning to January 2022.
Working in a COVID-19 area was a negative predictor of COVID-19 diagnosis in the present study. Some authors have already demonstrated no difference in the prevalence of SARS-CoV-2 infection between COVID-19 and non-COVID-19 areas.5, 15 It is possible that HCWs from COVID-19 areas, known to be at risk, are more careful than those HCWs of non-COVID-19 regions, which could explain the lower prevalence in our study.
We found that hospitalizations for COVID-19 were less common among vaccinated HCW, and there was no need for ICU admission or death among them. One study8 demonstrated that 84.2% of hospitalizations were from unvaccinated patients. Also, disease progression to mechanical ventilation or death was associated with a decreased likelihood of vaccination, and Antonelli et al.9 showed that vaccination was associated with reduced odds of hospitalization. In addition, vaccines may attenuate disease severity. Indeed, in the present study, dyspnea, and fatigue were less frequent among vaccinated HCWs. In a case series of postvaccination SARS-CoV-2 infection among HCW, the authors reported that the majority of HCW had mild (52.6%) or moderate (10.3%) disease with no need for hospitalization.11
On the other hand, we found that fever, sore throat, and coryza were more common among vaccinated HCW. This may reflect greater awareness of the disease among those vaccinated but could also be explained by other SARS-CoV-2 variants that are known to have slightly different clinical presentations. For example, the omicron variant is characterized by less lower respiratory tract involvement and more sore throat.16
One of the limitations of this study is that we recruited patients from a single tertiary university hospital; however, we do not think this is a limitation for generalizing the results. In addition, we did not evaluate COVID-19 vaccine-specific data, such as which vaccine was used; however, this was not the aim of the present study. Despite these concerns, to our knowledge, this is the first study in Brazil that evaluated COVID-19 among HCWs before and after vaccination.
In conclusion, SARS-CoV-2 infection prevalence was high among HCW, and vaccinated HCW had fewer hospitalizations, need for ICU, and deaths. These data confirm that vaccines may attenuate COVID-19 severity, and that efforts must be concentrated to ensure adequate vaccination for HCW.
AUTHOR CONTRIBUTIONS
Fábio Fernandes Dantas Filho: Conceptualization; methodology; investigation; writing—original draft. Eunice Beatriz Martin Chaves, Karen Gomes D'Avila, Jeruza Lavanholi Neyeloff, and Rodrigo Pires dos Santos: Conceptualization; investigation; resources; writing—review, and editing. Denise Rossato Silva: Conceptualization; methodology; investigation; supervision; project administration; funding acquisition; writing—original draft.
CONFLICTS OF INTEREST
The authors declare no conflicts of interest.
ETHICAL STATEMENT
Ethics approval was obtained from the Ethics Committee of Hospital de Clínicas de Porto Alegre in September 14, 2020 (number 200459).
Open Research
DATA AVAILABILITY STATEMENT
The data that support the findings of this study are available from the corresponding author upon reasonable request.
