Monitoring Report: Viral Gastroenteritis - August 2024 Data
Authors: Gratzl Samuel , Cartwright Brianna M Goodwin , Rodriguez Patricia J , Baker Charlotte , Do Duy , Stucky Nicholas L 
Published: May 2024

Background

Few sources regularly monitor hospitalizations associated with viral gastroenteritis. This study provides current hospitalization trends associated with two common viruses causing gastroenteritis: norovirus and rotavirus.

Objective

This study aims to supplement the surveillance data provided by the CDC by describing latest trends (through August 31, 2024) overall and for each virus. This study also provides valuable insight into two at-risk populations: infants and children (age 0-4) and older adults (age 65 and over).

Methods

Using a subset of real-world electronic health record (EHR) data from Truveta, a growing collective of health systems that provide more than 18% of all daily clinical care in the US, we identified people who were hospitalized between October 01, 2019 and August 31, 2024. We identified people who tested positive for each virus within 14 days of the hospitalization. We report monthly trends in the rate of hospitalizations associated with each virus per all hospitalizations and test positivity for the overall population and the two high-risk sub populations: infants and children and older adults.

Results

We included 8,153 hospitalizations of 7,939 unique patients who tested positive for a monitored virus between October 01, 2019 and August 31, 2024. Additionally, we included 354,235 lab results across 172,810 unique patients of which 15,741 were positive between October 01, 2019 and August 31, 2024.

Hospitalizations associated with these norovirus and rotavirus accounted for 0.04% of all hospitalizations in August 2024 (-18.2% from July 2024). The combined test positivity rate of these two enteric viruses was 3.6% in August 2024. For the population between age 0-4 years old, the hospitalizations associated with these two enteric viruses accounted for 0.08% of all hospitalizations in August (+196.7% from July 2024). The enteric virus test positivity rate was 10.3% for the month of August in this age group. In the population over 65 years of age, hospitalizations associated with these enteric viruses accounted for 0.04% of all hospitalizations in August 2024 (-26.0% from July 2024). The enteric virus test positivity rate was 2.4% for the month of August in this age group.

Discussion

We see evidence that we are in the nadir of the norovirus and rotavirus season for the overall population. The overall timeseries trends of hospitalizations associated with these viruses show a steady decrease over the last months, leading to a rate of 0.04% in August 2024 in the overall population. However, we see first indicators that the next season is already beginning for the population age 0-4 years old with an increase of the hospitalization rate of +196.7% from July.

In the overall and adult over age 65 population, norovirus causes 4 to 5 times higher hospitalization rates than rotavirus. However, in the population of infants and children, both viruses have similar hospitalization rates.

We will continue to monitor trends in common viruses causing gastroenteritis.

Trends in Surveillance

Overall population

Overall, the rate of hospitalizations associated with these two enteric viruses decreased from July to August (-18.2%). Norovirus-related hospitalizations decreased less than rotavirus-related hospitalizations (-16.2% vs -31.7%). Combined hospitalizations associated with these enteric viruses accounted for 0.04% of all hospitalizations in August 2024.

The combined test positivity rate of these two enteric viruses decreased from July to August to 3.6% (-11.6%). Norovirus test positivity rate decreased by 6.4%, while rotavirus test positivity rate decreased significantly by 39.5%.

Infants and children (age 0-4)

For the population between age 0-4 years old, the rate of hospitalizations associated with these two enteric viruses increased significantly from July to August (+196.7%). Both norovirus- and rotavirus-related hospitalizations increased (+256.0% and +137.3% respectively). Combined hospitalizations associated with these enteric viruses accounted for 0.08% of all hospitalizations in August in this age group.

For this population, the enteric virus test positivity rate increased significantly from July to August (+87.3% change). Norovirus test positivity rate increased significantly by 164.8%, while rotavirus test positivity rate increased by 8.9%. The enteric virus test positivity rate was 10.3% for the month of August in this age group.

Older adults (age 65 and over)

In the population over 65 years of age, there was a 26.0% decrease in the rate of hospitalizations associated with these two enteric viruses from July to August. Norovirus-related hospitalizations decreased (-24.8%), so did rotavirus-related hospitalizations (-39.1%). Combined hospitalizations associated with these enteric viruses accounted for 0.04% of all hospitalizations in August in this age group.

For this population, the enteric virus test positivity rate decreased from July to August (- 19.8% change). Norovirus test positivity rate decreased by 20.1%, and rotavirus test positivity rate by 1.2%. The enteric virus test positivity rate was 2.4% for the month of August in this age group.