Abstract Title
Sporadic, Medically Attended Norovirus Infection in the United States, 2023-2024
Presenter
Mark Schmidt, Kaiser Permanente Center for Health Research
Co-Author(s)
Mark A Schmidt, PhD, MPH; Kaiser Permanente Center for Health Research, Portland, OR USA
Holly C Groom, MPH; Kaiser Permanente Center for Health Research, Portland, OR USA
Laura J Tsaknaridis; Oregon State Public Health Laboratory, Hillsboro, OR USA
Matthew T Slaughter, MS; Kaiser Permanente Center for Health Research, Portland, OR USA
John F Dickerson, PhD; Kaiser Permanente Center for Health Research, Portland, OR USA
Ayo Ojebode, MPH, MLS (ASCP); Oregon State Public Health Laboratory, Hillsboro, OR USA
Lisa C. Morrow; Oregon State Public Health Laboratory, Hillsboro, OR USA
Riley Evans; Oregon State Public Health Laboratory, Hillsboro, OR USA
Sarah Vertrees, BS; Kaiser Permanente Center for Health Research, Portland, OR USA
Judy L Donald, MS; Kaiser Permanente Center for Health Research, Portland, OR USA
Maureen O’Keeffe-Rosetti, MS; Kaiser Permanente Center for Health Research, Portland, OR USA
Wen-Hsing Wu, MS; Moderna, Inc., Cambridge, MA USA
Carly Crocker, BS; Moderna, Inc., Cambridge, MA USA
Emma W Viscidi, PhD, MHS; Moderna, Inc., Cambridge, MA USA
Katherine B Carlson, PhD; Moderna, Inc., Cambridge, MA USA
Abstract Category
Epidemology
Abstract
Background
Our goal in conducting the Study of Acute Gastroenteritis (SAGE) was to describe the incidence and severity of sporadic, medically attended acute gastroenteritis (MAAGE) and norovirus (NoV) infection within the population of a large, integrated health care delivery system serving Oregon and Washington, USA.
Methods
From November 2023 to September 2024, we recruited health plan members of all ages with at least one MAAGE-coded health care visit. Participants completed an illness survey and submitted a stool specimen for norovirus detection and, if positive, genomic sequencing. We calculated incidence rates (IR) per 1,000 person-years (PY), with age-stratified, bootstrap 95% confidence intervals (CI). Variable differences were compared using chi-squared and Wilcoxon log rank sum testing, as appropriate.
Results
With 23,753 episodes identified, we estimated an all-age MAAGE IR of 61.0 per 1,000 PY (CI 60.2, 61.7). We enrolled 940 (4.0%) individuals, of whom 152 (16.1%) tested positive for NoV (IR 11.2 [CI 9.6, 12.9]). Of 114 (74%) genotyped NoV specimens, GII.17 (n=43; 38%) and GII.4 (n=20; 18%) predominated. GII.17 strains had higher polymerase and capsid region homology than those of GII.4. GII.4 was associated with a higher frequency of diarrhea (p=0.0368) and GII.17 trended towards a greater number of vomiting episodes (p=0.0568), but overall severity of disease did not differ (p=0.5819).
Conclusions
We provide estimates of sporadic MAAGE and NoV in a community-based setting and are consistent with the recent emergence of genotype GII.17. Disease severity was similar between GII.17 and GII.4, although we observed differences in their symptom profile.
Our goal in conducting the Study of Acute Gastroenteritis (SAGE) was to describe the incidence and severity of sporadic, medically attended acute gastroenteritis (MAAGE) and norovirus (NoV) infection within the population of a large, integrated health care delivery system serving Oregon and Washington, USA.
Methods
From November 2023 to September 2024, we recruited health plan members of all ages with at least one MAAGE-coded health care visit. Participants completed an illness survey and submitted a stool specimen for norovirus detection and, if positive, genomic sequencing. We calculated incidence rates (IR) per 1,000 person-years (PY), with age-stratified, bootstrap 95% confidence intervals (CI). Variable differences were compared using chi-squared and Wilcoxon log rank sum testing, as appropriate.
Results
With 23,753 episodes identified, we estimated an all-age MAAGE IR of 61.0 per 1,000 PY (CI 60.2, 61.7). We enrolled 940 (4.0%) individuals, of whom 152 (16.1%) tested positive for NoV (IR 11.2 [CI 9.6, 12.9]). Of 114 (74%) genotyped NoV specimens, GII.17 (n=43; 38%) and GII.4 (n=20; 18%) predominated. GII.17 strains had higher polymerase and capsid region homology than those of GII.4. GII.4 was associated with a higher frequency of diarrhea (p=0.0368) and GII.17 trended towards a greater number of vomiting episodes (p=0.0568), but overall severity of disease did not differ (p=0.5819).
Conclusions
We provide estimates of sporadic MAAGE and NoV in a community-based setting and are consistent with the recent emergence of genotype GII.17. Disease severity was similar between GII.17 and GII.4, although we observed differences in their symptom profile.