Hantavirus Disease and COVID-19

Evaluation of the Hantavirus 5-Point Screen in 139 COVID-19 Patients

Allison K. Joyce, MSc; Tarrah T. Oliver; Aaron D. Kofman, MD; Donna L. Talker; Shahrokh Safaeian; Deniz Peker Barclift, MD; Adam J. Perricone, MD, PhD; Shawn M. D'Andrea, MD; Amy N. Whitesell, MPH; Del Yazzie, MPH; Jeannette Guarner, MD; Mozafar Saleki, MS; Glynnis B. Ingall, MD, PhD; Mary J. Choi, MD; Ramona Antone-Nez, MPH


Am J Clin Pathol. 2022;157(3):470-475. 

In This Article

Materials and Methods

This project was conducted at three sites: Tséhootsooí Medical Center (TMC), Emory University Hospital, and Emory University Hospital Midtown. This activity was reviewed by the Centers for Disease Control and Prevention (CDC) and was conducted consistent with applicable federal law and CDC policy (see, eg, 45 C.F.R. part 46, 21 C.F.R. part 56; 42 U.S.C. §241(d); 5 U.S.C. §552a; 44 U.S.C. §3501 et seq.). It was also reviewed by ethical committees at TMC and Emory and received the determination of nonresearch at TMC and exempt research at Emory. Located in Fort Defiance, Arizona, in Navajo Nation, TMC is a 56-bed Public Law 93–638 self-determined hospital serving Navajo Nation. TMC's 25-bed emergency department has 40,000 visits annually. The closest facility with ECMO capability is the University of New Mexico Hospital in Albuquerque, New Mexico, which is 170 miles away. In May 2016, TMC implemented the hantavirus 5-point screen. To date, 189 screens have been performed and four cases of hantavirus disease have been identified (Tarrah T. Oliver, unpublished data, 2021).

Emory University Hospital and Emory University Hospital Midtown are, respectively, 751- and 529-bed academic teaching hospitals located in Atlanta, Georgia, and make up the two largest hospitals within the Emory Healthcare System of metropolitan Atlanta. Emory University Hospital's 36-bed emergency department has 36,000 visits annually.

From April to May 2020, TMC conducted hantavirus screens on all patients who sought treatment from the hospital with signs and symptoms suggestive of COVID-19. At TMC, the screens were performed and interpreted by medical laboratory technicians and medical technologists. In March and April 2020, the Emory sites retrospectively identified all patients with a positive molecular COVID-19 test. Two pathologists performed and interpreted the hantavirus 5-point screens for these individuals. All screens were evaluated in accordance with the protocol established by TMC (Supplementary Figure S1; all supplemental materials can be found at American Journal of Clinical Pathology online).[15] Both institutions use automated instruments to perform CBC counts and WBC differentials with the following workflow: the samples were placed on the Sysmex XN-L instrument, which uses flow cytometry technology. If the sample showed any alteration that is flagged based on set instrument parameters, a smear would be produced and stained automatically using a stainer (SP-50; Sysmex). Using CellaVison DI60 (Sysmex), the stained smear was scanned, and WBCs were photographed and sorted into the different categories. Medical scientists approved the sorting done by the image analyzer or changed particular cells to a different category if necessary as part of the manual differential. These CBCs and smears were used to determine the presence of the five criteria of the 5-point screen based on the following parameters. Thrombocytopenia was defined as a platelet count less than 150 × 109/L. Significant toxic change in neutrophils was defined as a grade 2+ or more. Immunoblasts and plasma cells were present in a concentration more than 10% of lymphoid cells. Different normal ranges for hemoglobin and hematocrit were used for the two sites, as elevation differs between Fort Defiance, AZ, and Atlanta, GA. Hemoglobin values 18 g/dL or more for men and 16 g/dL or more for women, as well as hematocrit values 52% or more for men and 48% or more for women were considered elevated for TMC. Hemoglobin values 16.1 g/dL or more for men and 14.4 g/dL or more for women, as well as hematocrit values 46.5% or more for men and 41.4% or more for women were considered elevated for Emory. Last, there is no specific range for left shift. If the algorithm within the analyzer detects immature granulocytes over 5%, medical scientists or pathologists will conduct a manual differential and look for immature neutrophilic cells to identify left shift.

COVID-19 molecular testing was performed on all project participants. Participants whose COVID-19 test was negative were excluded from the project. For both TMC and the Emory sites, a repeat platelet count that was obtained within 12 to 24 hours was available for a subset of individuals at provider discretion. COVID-19 serology was not performed.

Project investigators reviewed the medical records for all enrolled participants. For each participant, the following information was collected: demographics, medical history (to include comorbidities known to be associated with thrombocytopenia and/or are associated with an increased risk of severe COVID-19), clinical presentation, and outcome. As the hantavirus 5-point screen is most accurate when the specimen is collected during the cardiopulmonary phase, a composite variable of respiratory symptoms was created to determine the percentage of patients with COVID-19 who had their sample collected while they were experiencing respiratory symptoms.[10] Respiratory symptoms were considered present if any of the following criteria was met: presence of cough and/or shortness of breath and/or an oxygen saturation of less than 93%.

Analysis of the clinical data and the hantavirus screen data was conducted in a combination of Excel 2008 (Microsoft) and SAS 9.4 (SAS Institute). Frequencies were calculated for the categorical variables, and descriptive statistics, including mean, median, range, and interquartile range, were calculated for the continuous variables. The χ2 tests were done for the categorical variables, except where Fisher exact test was appropriate. For the continuous variables, a two-sample t test was done for age, and the Mann-Whitney U test was done for duration of hospitalization. Statistical tests were also done comparing the average scores received on the hantavirus screen to a hypothesized value of 4/5, a score that indicates high suspicion for HCPS. A one-sample sign test was done for the skewed TMC population, and a one-sample t test was done for the normally distributed Emory population.