Adverse Events Following One Dose of mRNA COVID-19 Vaccination Among US Nursing Home Residents With and Without a Previous SARS-CoV-2 Infection

ObjectivesTo compare rates of adverse events following Coronavirus Disease 2019 (COVID-19) vaccination among nursing home residents with and without previous severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection.DesignProspective cohort.Setting and ParticipantsA total of 20,918 nursing home residents who received the first dose of messenger RNA COVID-19 vaccine from December 18, 2020, through February 14, 2021, in 284 facilities within Genesis Healthcare, a large nursing home provider spanning 24 US states.MethodsWe screened the electronic health record for adverse events, classified by the Brighton Collaboration, occurring within 15 days of a resident’s first COVID-19 vaccine dose. All events were confirmed by physician chart review. To obtain risk ratios, multilevel logistic regression model that accounted for clustering (variability) across nursing homes was implemented. To balance the probability of prior SARS-CoV-2 infection (previous positive test or diagnosis by the International Classification of Diseases, 10^th Revision, Clinical Modification) more than 20 days before vaccination, we used inverse probability weighting. To adjust for multiplicity of adverse events tested, we used a false discovery rate procedure.ResultsStatistically significant differences existed between those without (n = 13,163) and with previous SARS-CoV-2 infection [symptomatic (n = 5617) and asymptomatic (n = 2138)] for all baseline characteristics assessed. Only 1 adverse event was reported among those with previous SARS-CoV-2 infection (asymptomatic), venous thromboembolism [46.8 per 100,000 residents 95% confidence interval (CI) 8.3–264.5], which was not significantly different from the rate reported for those without previous infection (30.4 per 100,000 95% CI 11.8–78.1). Several other adverse events were observed for those with no previous infection, but were not statistically significantly higher than those reported with previous infection after adjustments for multiple comparisons.Conclusions and ImplicationsAlthough reactogenicity increases with preexisting immunity, we did not find that vaccination among those with previous SARS-CoV-2 infection resulted in higher rates of adverse events than those without previous infection. This study stresses the importance of monitoring novel vaccines for adverse events in this vulnerable population.     

SARS-CoV-2 and Wisconsin Nursing Homes: Temporal Dynamics During the COVID-19 Pandemic

ObjectivesEvidence suggests that quality, location, and staffing levels may be associated with COVID-19 incidence in nursing homes. However, it is unknown if these relationships remain constant over time. We describe incidence rates of COVID-19 across Wisconsin nursing homes while examining factors associated with their trajectory during 5 months of the pandemic.DesignRetrospective cohort study.Setting/ParticipantsWisconsin nursing homes.MethodsPublicly available data from June 1, 2020, to October 31, 2020, were obtained. These included facility size, staffing, 5-star Medicare rating score, and components. Nursing home characteristics were compared using Pearson chi-square and Kruskal-Wallis tests. Multiple linear regressions were used to evaluate the effect of rurality on COVID-19.ResultsThere were a total of 2459 COVID-19 cases across 246 Wisconsin nursing homes. Number of beds (P < .001), average count of residents per day (P < .001), and governmental ownership (P = .014) were associated with a higher number of COVID-19 cases. Temporal analysis showed that the highest incidence rates of COVID-19 were observed in October 2020 (30.33 cases per 10,000 nursing home occupied-bed days, respectively). Urban nursing homes experienced higher incidence rates until September 2020; then incidence rates among rural nursing homes surged. In the first half of the study period, nursing homes with lower-quality scores (1-3 stars) had higher COVID-19 incidence rates. However, since August 2020, incidence was highest among nursing homes with higher-quality scores (4 or 5 stars). Multivariate analysis indicated that over time rural location was associated with increased incidence of COVID-19 (β = 0.05, P = .03).Conclusions and ImplicationsHigher COVID-19 incidence rates were first observed in large, urban nursing homes with low-quality rating. By October 2020, the disease had spread to rural and smaller nursing homes and those with higher-quality ratings, suggesting that community transmission of SARS-CoV-2 may have propelled its spread.     

Remote Infection Control Assessments of US Nursing Homes During the COVID-19 Pandemic,April to June 2020

BackgroundNursing homes (NHs) provide care in a congregate setting for residents at high risk of severe outcomes from SARS-CoV-2 infection. In spring 2020, NHs were implementing new guidance to minimize SARS-CoV-2 spread among residents and staff.ObjectiveTo assess whether telephone and video-based infection control assessment and response (TeleICAR) strategies could efficiently assess NH preparedness and help resolve gaps.DesignWe incorporated Centers for Disease Control and Prevention COVID-19 guidance for NH into an assessment tool covering 6 domains: visitor restrictions; health care personnel COVID-19 training; resident education, monitoring, screening, and cohorting; personal protective equipment supply; core infection prevention and control (IPC); and communication to public health. We performed TeleICAR consultations on behalf of health departments. Adherence to each element was documented and recommendations provided to the facility.Setting and ParticipantsHealth department–referred NHs that agreed to TeleICAR consultation.MethodsWe assessed overall numbers and proportions of NH that had not implemented each infection control element (gap) and proportion of NH that reported making ≥1 change in practice following the assessment.ResultsDuring April 13 to June 12, 2020, we completed TeleICAR consultations in 629 NHs across 19 states. Overall, 524 (83%) had ≥1 implementation gap identified; the median number of gaps was 2 (interquartile range: 1-4). The domains with the greatest number of facilities with gaps were core IPC practices (428/625; 68%) and COVID-19 education, monitoring, screening, and cohorting of residents (291/620; 47%).Conclusions and ImplicationsTeleICAR was an alternative to onsite infection control assessments that enabled public health to efficiently reach NHs across the United States early in the COVID-19 pandemic. Assessments identified widespread gaps in core IPC practices that put residents and staff at risk of infection. TeleICAR is an important strategy that leverages infection control expertise and can be useful in future efforts to improve NH IPC.     

Greater Opioid Use Among Nursing Home Residents in Ontario,Canada During the First 2 Waves of the COVID-19 Pandemic

ObjectivesTo examine the association between the COVID-19 pandemic and opioid use among nursing home residents followed up to March 2021, and possible variation by dementia and frailty status.DesignPopulation-based cohort study with an interrupted time series analysis.Setting and ParticipantsLinked health administrative databases for residents of all nursing homes (n = 630) in Ontario, Canada were examined. Residents were divided into consecutive weekly cohorts (first observation week was March 5 to 11, 2017 and last was March 21 to March 27, 2021).MethodsThe weekly proportion of residents dispensed an opioid was examined overall and by strata defined by the presence of dementia and frailty. Autoregressive Integrated Moving Average models with step and ramp intervention functions tested for immediate level and slope changes in weekly opioid use after the onset of the pandemic (March 1, 2020) and were fit on prepandemic data for projected trends.ResultsThe average weekly cohort ranged from 76,834 residents (prepandemic) to 69,359 (pandemic period), with a consistent distribution by sex (69% female) and age (54% age 85 + years). There was a statistically significant increased slope change in the weekly proportion of residents dispensed opioids (parameter estimate (β) = 0.035; standard error (SE) = 0.005, P < .001). Although significant for all 4 strata, the increased slope change was more pronounced among nonfrail residents (β = 0.038; SE = 0.008, P < .001) and those without dementia (β = 0.044; SE = 0.008, P < .001). The absolute difference in observed vs predicted opioid use in the last week of the pandemic period ranged from 1.25% (frail residents) to 2.28% (residents without dementia).Conclusions and ImplicationsAmong Ontario nursing home residents, there was a statistically significant increase in opioid dispensations following the onset of the pandemic that persisted up to 1 year later. Investigations of the reasons for increased use, potential for long-term use and associated health consequences for residents are warranted.     

Mortality of Care Home Residents and Community-Dwelling Controls During the COVID-19 Pandemic in 2020: Matched Cohort Study

ObjectiveThis study aimed to estimate and compare mortality of care home residents, and matched community-dwelling controls, during the COVID-19 pandemic from primary care electronic health records in England.DesignMatched cohort study.Setting and ParticipantsFamily practices in England in the Clinical Practice Research Datalink Aurum database. There were 83,627 care home residents in 2020, with 26,923 deaths; 80,730 (97%) were matched on age, sex, and family practice with 300,445 community-dwelling adults.MethodsAll-cause mortality was evaluated and adjusted rate ratios by negative binomial regression were adjusted for age, sex, number of long-term conditions, frailty category, region, calendar month or week, and clustering by family practice.ResultsUnderlying mortality of care home residents was higher than community controls (adjusted rate ratio 5.59, 95% confidence interval 5.23?5.99, P < .001). During April 2020, there was a net increase in mortality of care home residents over that of controls. The mortality rate of care home residents was 27.2 deaths per 1000 patients per week, compared with 2.31 per 1000 for controls. Excess deaths for care home residents, above that predicted from pre-pandemic years, peaked between April 13 and 19 (men, 27.7, 95% confidence interval 25.1?30.3; women, 17.4, 15.9?18.8 per 1000 per week). Compared with care home residents, long-term conditions and frailty were differentially associated with greater mortality in community-dwelling controls.Conclusions and ImplicationsIndividual-patient data from primary care electronic health records may be used to estimate mortality in care home residents. Mortality is substantially higher than for community-dwelling comparators and showed a disproportionate increase in the first wave of the COVID-19 pandemic. Care home residents require particular protection during periods of high infectious disease transmission.     

Nursing Home Workers’ Mental Health During the COVID-19 Pandemic in France

ObjectivesThe present study sought to examine mental health problems among nursing home workers in the context of the COVID-19 pandemic, to investigate COVID-19–related fears, and to identify prepandemic factors associated with current mental health issues.DesignA cross-sectional, online survey was used.Setting and ParticipantsAll employees among 6 nursing homes in southwestern France (N = 455) were solicited between November, 2020 and June, 2021.MethodsThe survey instrument was developed within the World Mental Health consortium to screen for COVID-related fears, probable generalized anxiety, panic attacks, depression, posttraumatic stress and substance use disorders in the past 30 days.ResultsThe survey was completed by 127 workers (89.0% female, mean age = 43.42 years, SD = 11.29), yielding a 28.5% response rate. Overall, 48.03% reported experiencing fear of infecting others at least most of the time. One in 8 (14.96%) indicated that close others feared being infected by them. One-third of the sample (34.65%) met criteria for at least 1 probable current mental disorder. Panic attacks (22.05%) were the most frequently reported mental health problem, followed by depression (16.54%). In multivariate analyses, the only factor associated with having a current probable mental disorder was the presence of any prepandemic mental health problem (adjusted odds ratio 4.76, 95% CI 2.08-10.89). Type of employment contract, full-time status, and medical vs nonmedical staff status were not significantly associated with mental health status.Conclusions and ImplicationsThe study reveals that one-third of nursing home workers in the sample report current probable mental disorders, and these were largely associated with prepandemic mental health status. Screening for common mental health problems and facilitating access to appropriate care should be prioritized in nursing homes.     

Absence of COVID-19 Disease Among Chronically Ventilated Nursing Home Patients

ObjectiveTo describe the experience of COVID-19 disease among chronically ventilated and nonventilated nursing home patients living in 3 separate nursing homes.DesignObservational study of death, respiratory illness and COVID-19 polymerase chain reaction (PCR) results among residents and staff during nursing home outbreaks in 2020.Setting and Participants93 chronically ventilated nursing home patients and 1151 nonventilated patients living among 3 separate nursing homes on Long Island, New York, as of March 15, 2020. Illness, PCR results, and antibody studies among staff are also reported.MeasurementsData were collected on death rate among chronically ventilated and nonventilated patients between March 15 and May 15, 2020, compared to the same time in 2019; prevalence of PCR positivity among ventilated and nonventilated patients in 2020; reported illness, PCR positivity, and antibody among staff.ResultsTotal numbers of deaths among chronically ventilated nursing home patients during this time frame were similar to the analogous period 1 year earlier (9 of 93 in 2020 vs 8 of 100 in 2019, P = .8), whereas deaths among nonventilated patients were greatly increased (214 of 1151 in 2020 vs 55 of 1189 in 2019, P < .001). No ventilated patient deaths were clinically judged to be COVID-19 related. No clusters of COVID-19 illness could be demonstrated among ventilated patients. Surveillance PCR testing of ventilator patients failed to reveal COVID-19 positivity (none of 84 ventilator patients vs 81 of 971 nonventilator patients, P < .002). Illness and evidence of COVID-19 infection was demonstrated among staff working both in nonventilator and in ventilator units.Conclusions and ImplicationsCOVID-19 infection resulted in illness and death among nonventilated nursing home residents as well as among staff. This was not observed among chronically ventilated patients. The mechanics of chronic ventilation appears to protect chronically ventilated patients from COVID-19 disease.     

The Adverse Effects of the COVID-19 Pandemic on Nursing Home Resident Well-Being

ObjectiveQuantify the effects of the COVID-19 pandemic on nursing home resident well-being.DesignQuantitative analysis of resident-level assessment data.Setting and participantsLong-stay residents living in Connecticut nursing homes.MethodsWe used Minimum Data Set assessments to measure nursing home resident outcomes observed in each week between March and July 2020 for long-stay residents (eg, those in the nursing home for at least 100 days) who lived in a nursing home at the beginning of the pandemic. We compared outcomes to those observed at the beginning of the pandemic, controlling for both resident characteristics and patterns for outcomes observed in 2017-2019.ResultsWe found that nursing home resident outcomes worsened on a broad array of measures. The prevalence of depressive symptoms increased by 6 percentage points relative to before the pandemic in the beginning of March—representing a 15% increase. The share of residents with unplanned substantial weight loss also increased by 6 percentage points relative to the beginning of March—representing a 150% increase. We also found significant increases in episodes of incontinence (4 percentage points) and significant reductions in cognitive functioning. Our findings suggest that loneliness and isolation play an important role. Though unplanned substantial weight loss was greatest for those who contracted COVID-19 (about 10% of residents observed in each week), residents who did not contract COVID-19 also physically deteriorated (about 7.5% of residents in each week).Conclusions and ImplicationsThese analyses show that the pandemic had substantial impacts on nursing home residents beyond what can be quantified by cases and deaths, adversely affecting the physical and emotional well-being of residents. Future policy changes to limit the spread of COVID-19 or other infectious disease outbreaks should consider any additional costs beyond the direct effects of morbidity and mortality due to COVID-19.     

Ecological Analysis of the Decline in Incidence Rates of COVID-19 Among Nursing Home Residents Associated with Vaccination,United States,December 2020-January 2021

ObjectiveTo evaluate if facility-level vaccination after an initial vaccination clinic was independently associated with COVID-19 incidence adjusted for other factors in January 2021 among nursing home residents.DesignEcological analysis of data from the CDC's National Healthcare Safety Network (NHSN) and from the CDC's Pharmacy Partnership for Long-Term Care Program.Setting and ParticipantsCMS-certified nursing homes participating in both NHSN and the Pharmacy Partnership for Long-Term Care Program.MethodsA multivariable, random intercepts, negative binomial model was applied to contrast COVID-19 incidence rates among residents living in facilities with an initial vaccination clinic during the week ending January 3, 2021 (n = 2843), vs those living in facilities with no vaccination clinic reported up to and including the week ending January 10, 2021 (n = 3216). Model covariates included bed size, resident SARS-CoV-2 testing, staff with COVID-19, cumulative COVID-19 among residents, residents admitted with COVID-19, community county incidence, and county social vulnerability index (SVI).ResultsIn December 2020 and January 2021, incidence of COVID-19 among nursing home residents declined to the lowest point since reporting began in May, diverged from the pattern in community cases, and began dropping before vaccination occurred. Comparing week 3 following an initial vaccination clinic vs week 2, the adjusted reduction in COVID-19 rate in vaccinated facilities was 27% greater than the reduction in facilities where vaccination clinics had not yet occurred (95% confidence interval: 14%-38%, P < .05).Conclusions and ImplicationsVaccination of residents contributed to the decline in COVID-19 incidence in nursing homes; however, other factors also contributed. The decline in COVID-19 was evident prior to widespread vaccination, highlighting the benefit of a multifaced approach to prevention including continued use of recommended screening, testing, and infection prevention practices as well as vaccination to keep residents in nursing homes safe.     

Risk of Death in Nursing Home Residents After COVID-19 Vaccination

ObjectivesIn the first months of 2021, the Dutch COVID-19 vaccination campaign was disturbed by reports of death in Norwegian nursing homes (NHs) after vaccination. Reports predominantly concerned persons >65 years of age with 1 or more comorbidities. Also, in the Netherlands adverse events were reported after COVID-19 vaccination in this vulnerable group. Yet, it was unclear whether a causal link between vaccination and death existed. Therefore, we investigated the risk of death after COVID-19 vaccination in Dutch NH residents compared with the risk of death in NH residents prior to the COVID-19 pandemic.DesignPopulation-based longitudinal cohort study with electronic health record data.Setting and ParticipantsWe studied Dutch NH residents from 73 NHs who received 1 or 2 COVID-19 vaccination(s) between January 13 and April 16, 2021 (n = 21,762). As a historical comparison group, we included Dutch NH residents who were registered in the same period in 2019 (n = 27,591).MethodsData on vaccination status, age, gender, type of care, comorbidities, and date of NH entry and (if applicable) discharge or date of death were extracted from electronic health records. Risk of death after 30 days was evaluated and compared between vaccinated residents and historical comparison residents with Kaplan-Meier and Cox regression analyses. Regression analyses were adjusted for age, gender, comorbidities, and length of stay.ResultsRisk of death in NH residents after one COVID-19 vaccination (regardless of whether a second vaccination was given) was decreased compared with historical comparison residents from 2019 (adjusted HR 0.77, 95% CI 0.69-0.86). The risk of death further decreased after 2 vaccinations compared with the historical comparison group (adjusted HR 0.57, 95% CI 0.50-0.64).Conclusions and ImplicationsWe found no indication that risk of death in NH residents is increased after COVID-19 vaccination. These results indicate that COVID-19 vaccination in NH residents is safe and could reduce fear and resistance toward vaccination.     

Front-line Nursing Home Staff Experiences During the COVID-19 Pandemic

ObjectiveThe Coronavirus disease 2019 (COVID-19) pandemic is an unprecedented challenge for nursing homes, where staff have faced rapidly evolving circumstances to care for a vulnerable resident population. Our objective was to document the experiences of these front-line health care professionals during the pandemic.DesignElectronic survey of long-term care staff. This report summarizes qualitative data from open-ended questions for the subset of respondents working in nursing homes.Setting and ParticipantsA total of 152 nursing home staff from 32 states, including direct-care staff and administrators.MethodsFrom May 11 through June 4, 2020, we used social media and professional networks to disseminate an electronic survey with closed- and open-ended questions to a convenience sample of long-term care staff. Four investigators identified themes from qualitative responses for staff working in nursing homes.ResultsRespondents described ongoing constraints on testing and continued reliance on crisis standards for extended use and reuse of personal protective equipment. Administrators discussed the burden of tracking and implementing sometimes confusing or contradictory guidance from numerous agencies. Direct-care staff expressed fears of infecting themselves and their families, and expressed sincere empathy and concern for their residents. They described experiencing burnout due to increased workloads, staffing shortages, and the emotional burden of caring for residents facing significant isolation, illness, and death. Respondents cited the presence or lack of organizational communication and teamwork as important factors influencing their ability to work under challenging circumstances. They also described the demoralizing impact of negative media coverage of nursing homes, contrasting this with the heroic public recognition given to hospital staff.Conclusions and ImplicationsNursing home staff described working under complex and stressful circumstances during the COVID-19 pandemic. These challenges have added significant burden to an already strained and vulnerable workforce and are likely to contribute to increased burnout, turnover, and staff shortages in the long term.     

A Longitudinal,Clinical, and Spatial Epidemiologic Analysis of a Large COVID-19 Long-Term Care Home Outbreak

ObjectivesCOVID-19 has had devastating effects on long-term care homes across much of the world, and especially within Canada, with more than 50% of the mortality from COVID-19 in 2020 in these homes. Understanding the way in which the virus spreads within these homes is critical to preventing further outbreaks.DesignRetrospective chart review.Settings and ParticipantsLong-term care home residents and staff in Ontario, Canada.MethodsWe conducted a longitudinal study of a large long-term care home COVID-19 outbreak in Ontario, Canada, using electronic medical records, public health records, staff assignments, and resident room locations to spatially map the outbreak through the facility.ResultsBy analyzing the outbreak longitudinally, we were able to draw 3 important conclusions: (1) 84.5% had typical COVID-19 symptoms and only 15.5% of residents had asymptomatic infection; (2) there was a high attack rate of 85.8%, which appeared to be explained by a high degree of interconnectedness within the home exacerbated by staffing shortages; and (3) clustering of infections within multibedded rooms was common.Conclusion and ImplicationsLow rates of asymptomatic infection suggest that symptom-based screening in residents remains very important for detecting outbreaks, a high degree of interconnectedness explains the high attack rate, and there is a need for improved guidance for homes with multibedded rooms on optimizing resident room movement to mitigate spread of COVID-19 in long-term care homes.     

SARS-CoV-2 Sequence Analysis during COVID-19 Case Surge,Liberia, 2021

In June 2021, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) cases surged in Liberia. SARS-CoV-2 sequences from patients hospitalized during March–July 2021 revealed the Delta variant was in Liberia in early March and was dominant in June, irrespective of geography. Mutations and deletions suggest multiple SARS-CoV-2 Delta variant introductions.     

Risk Factors for SARS-CoV-2 Infection Among US Healthcare Personnel,May–December 2020

To determine risk factors for coronavirus disease (COVID-19) among US healthcare personnel (HCP), we conducted a case–control analysis. We collected data about activities outside the workplace and COVID-19 patient care activities from HCP with positive severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) test results (cases) and from HCP with negative test results (controls) in healthcare facilities in 5 US states. We used conditional logistic regression to calculate adjusted matched odds ratios and 95% CIs for exposures. Among 345 cases and 622 controls, factors associated with risk were having close contact with persons with COVID-19 outside the workplace, having close contact with COVID-19 patients in the workplace, and assisting COVID-19 patients with activities of daily living. Protecting HCP from COVID-19 may require interventions that reduce their exposures outside the workplace and improve their ability to more safely assist COVID-19 patients with activities of daily living.     

The Effects of ARBs,ACEis, and Statins on Clinical Outcomes of COVID-19 Infection Among Nursing Home Residents

ObjectivesAngiotensin-converting enzyme inhibitors (ACEi), angiotensin II receptor blockers (ARBs), and HMG-CoA reductase inhibitors (“statins”) have been hypothesized to affect COVID-19 severity. However, up to now, no studies investigating this association have been conducted in the most vulnerable and affected population groups (ie, older adults residing in nursing homes). The objective of this study was to explore the association of ACEi/ARB and/or statins with clinical manifestations in COVID-19–infected older adults residing in nursing homes.DesignWe undertook a retrospective multicenter cohort study to analyze the association between ACEi/ARB and/or statin use with clinical outcome of COVID-19. The outcomes were (1) serious COVID-19 defined as long-stay hospital admission or death within 14 days of disease onset, and (2) asymptomatic (ie, no disease symptoms in the whole study period while still being diagnosed by polymerase chain reaction).Setting and participantsA total of 154 COVID-19–positive subjects were identified, residing in 1 of 2 Belgian nursing homes that experienced similar COVID-19 outbreaks.MeasuresLogistic regression models were applied with age, sex, functional status, diabetes, and hypertension as covariates.ResultsWe found a statistically significant association between statin intake and the absence of symptoms during COVID-19 (odds ratio [OR] 2.91; confidence interval [CI] 1.27–6.71), which remained statistically significant after adjusting for covariates (OR 2.65; CI 1.13–6.68). Although the effects of statin intake on serious clinical outcome were in the same beneficial direction, these were not statistically significant (OR 0.75; CI 0.24–1.87). There was also no statistically significant association between ACEi/ARB and asymptomatic status (OR 2.72; CI 0.59–25.1) or serious clinical outcome (OR 0.48; CI 0.10–1.97).Conclusions and ImplicationsOur data indicate that statin intake in older, frail adults could be associated with a considerable beneficial effect on COVID-19 clinical symptoms. The role of statins and renin-angiotensin system drugs needs to be further explored in larger observational studies as well as randomized clinical trials.     

A Robotic Device to Enhance Nursing Home Provider Telepresence During and After the COVID-19 Pandemic

The COVID-19 pandemic presented significant challenges to face-to-face communication with people residing in post-acute and long-term care (PALTC) settings. Telemedicine is an alternative, but facility staff may be overburdened with the management of the equipment. Here we introduce the use of a mobile HIPPA-compliant telepresence robot (MTR) to bridge this barrier, which may be beneficial to reimagine options for PALTC in the future.     

新型冠状病毒疫苗接种对成都市境外输入病例流行病学及临床特征的影响分析

目的:分析新型冠状病毒（新冠病毒）疫苗接种对成都市境外输入病例流行病学及临床特征的影响,为新型冠状病毒肺炎疫情防控提供参考依据。方法:截至2021年4月15日,经成都市入境的新冠病毒感染病例,根据新冠病毒疫苗接种史被分为疫苗接种组和疫苗未接种组。回顾性收集和分析病例的流行病学及临床特征资料。实验室检测项目包括新冠病毒核...