Respiratory Virus Weekly Report

California laboratories report SARS-CoV-2 test results to CDPH through electronic laboratory reporting. Los Angeles County SARS-CoV-2 lab data has a 7-day reporting lag. Test positivity is calculated using SARS-CoV-2 lab tests that has a specimen collection date reported during a given week. Weeks are defined as Sunday through Saturday. Test positivity is the number of positive SARS-CoV-2 results divided by the total number of SARS-CoV-2 tests.

Laboratory surveillance for influenza, respiratory syncytial virus (RSV), and other respiratory viruses involves the use of data from clinical sentinel laboratories (hospital, academic or private) located throughout California. Specimens for testing are collected from patients in healthcare settings and do not reflect all testing for influenza, RSV, and other respiratory viruses in California. These laboratories report the number of laboratory-confirmed influenza, RSV, and other respiratory virus detections and isolations, and the total number of specimens tested by virus type on a weekly basis. Test positivity for a given week (Sunday through Saturday) is calculated by dividing the number of positive influenza results by the total number of specimens tested for influenza.

Laboratory surveillance for influenza, respiratory syncytial virus (RSV), and other respiratory viruses involves the use of data from clinical sentinel laboratories (hospital, academic or private) located throughout California. Specimens for testing are collected from patients in healthcare settings and do not reflect all testing for influenza, RSV, and other respiratory viruses in California. These laboratories report the number of laboratory-confirmed influenza, RSV, and other respiratory viruses and isolations, and the total number of specimens tested by virus type on a weekly basis. Test positivity for a given week (Sunday through Saturday) is calculated by dividing the number of positive RSV results by the total number of specimens tested for RSV.

Laboratory surveillance for influenza, respiratory syncytial virus (RSV) and other respiratory viruses involves the use of data from clinical sentinel laboratories (hospital, academic or private) located throughout California. Other respiratory viruses include parainfluenza types 1-4, human metapneumovirus, non-SARS-CoV-2 coronaviruses, adenovirus, and enterovirus/rhinovirus. Specimens for testing are collected from patients in healthcare settings and do not reflect all testing for influenza, RSV, and other respiratory viruses in California. These laboratories report the number of laboratory-confirmed influenza, RSV, and other respiratory virus detections and isolations, and the total number of specimens tested by virus type on a weekly basis. Test positivity for a given week (Sunday through Saturday) is calculated by dividing the number of positive results for each virus by the total number of specimens tested for each virus.

CDPH collaborates with Northern California Kaiser Permanente (NCKP) to monitor trends in respiratory syncytial virus (RSV) admissions. RSV-related admissions at NCKP hospitals are defined as those with diagnoses that include 'RSV,' 'syncytial,' or 'bronchiolitis.' The percentage of RSV admissions is calculated by dividing the number of RSV-related admissions by the total number of admissions during the same period. Admissions for pregnancy, labor and delivery, birth and outpatient procedures are not included in total number of admissions. These admissions serve as a proxy for RSV activity and do not necessarily represent laboratory confirmed RSV hospitalizations; NCKP members are not representative of all Californians.

CDPH receives weekly year-to-date dynamic data on deaths occurring in California from the CDPH Center for Health Statistics and Informatics. These data are limited to deaths occurring in California residents and are analyzed to identify COVID-19-coded deaths. COVID-19-coded deaths are defined as deaths with COVID-19 noted in any cause of death field on the death certificate (COVID-19 specified in a literal [text] cause of death field, or a COVID-19 ICD-10 code in a coded cause of death field). COVID-19-coded deaths are not necessarily laboratory-confirmed and are likely to be an underestimate of all COVID-19-associated deaths. CDPH calculates the percentage of COVID-19-coded deaths by dividing the number of COVID-19-coded deaths by the total number of all cause deaths during the same period.

CDPH receives weekly year-to-date dynamic data on deaths occurring in California from the CDPH Center for Health Statistics and Informatics. These data are limited to deaths occurring in California residents and are analyzed to identify influenza-coded deaths. Influenza-coded deaths are defined as deaths with influenza noted in any cause of death field on the death certificate (influenza specified in a literal [text] cause of death field or an influenza ICD-10 code in a coded cause of death field). Influenza-coded deaths are not necessarily laboratory-confirmed and are likely to be an underestimate of all influenza-associated deaths. CDPH calculates the percentage of influenza-coded deaths by dividing the number of influenza-coded deaths by the total number of all cause deaths during the same period.

CDPH receives weekly year-to-date dynamic data on deaths occurring in California from the CDPH Center for Health Statistics and Informatics. These data are limited to deaths occurring in California residents and are analyzed to identify respiratory syncytial virus (RSV)-coded deaths. RSV-coded deaths are defined as deaths with RSV noted in any cause of death field on the death certificate (RSV specified in a literal [text] cause of death field or an RSV ICD-10 code in a coded cause of death field). RSV-coded deaths are not necessarily laboratory-confirmed and are likely to be an underestimate of all RSV-associated deaths. CDPH calculates the percentage of RSV-coded deaths by dividing the number of RSV-coded deaths by the total number of all cause deaths during the same period.

CDPH receives weekly year-to-date dynamic data on deaths occurring in California from the CDPH Center for Health Statistics and Informatics. These data are limited to deaths occurring in California residents and are analyzed to identify influenza, respiratory syncytial virus (RSV), and COVID-19-coded deaths. These deaths are not necessarily laboratory-confirmed and are an underestimate of all influenza, RSV and COVID-19-associated deaths. The counts of influenza, RSV and COVID-19-coded deaths by age group are calculated by summing the total number of disease-specific deaths for each age group (<5 years, 5-17 years, 18-49 years, 50-64 years, 65+ years).

This dataset represents statewide weekly SARS-CoV-2 wastewater summary values. SARS-CoV-2 wastewater concentrations from all sites in California are combined into a single, statewide, unit-less summary value for each week, using a method for data transformation and aggregation developed by the CDC National Wastewater Surveillance System (NWSS). Please see the CDC NWSS data methods page for a description of how these summary values are calculated. Weeks are defined as Sunday through Saturday.

The dataset contains COVID-19-associated hospital admissions are from Centers for Disease Control and Prevention’s (CDC) National Healthcare Safety Network (NHSN) Hospitalization dataset. The requirement to report COVID-19 and influenza-associated hospitalizations was effective November 1, 2024. CDPH pulls NHSN data from the CDC on the Wednesday prior to the publication of the report. Results may differ depending on which day data are pulled. Admission rates are calculated using population estimates from the P-3: Complete State and County Projections Dataset provided by the State of California Department of Finance (https://dof.ca.gov/forecasting/demographics/projections/). Reported weekly admission rates for the entire season use the population estimates for the year the season started. For more information on NHSN data including the protocol and data collection information, see the CDC NHSN webpage (https://www.cdc.gov/nhsn/index.html). Weekly hospitalization data are defined as Sunday through Saturday.

The dataset contains influenza-associated hospital admissions are from Centers for Disease Control and Prevention’s (CDC) National Healthcare Safety Network (NHSN) Hospitalization dataset. The requirement to report COVID-19 and influenza-associated hospitalizations was effective November 1, 2024. CDPH pulls NHSN data from the CDC on the Wednesday prior to the publication of the report. Results may differ depending on which day data are pulled. Admission rates are calculated using population estimates from the P-3: Complete State and County Projections Dataset provided by the State of California Department of Finance (https://dof.ca.gov/forecasting/demographics/projections/). Reported weekly admission rates for the entire season use the population estimates for the year the season started. For more information on NHSN data including the protocol and data collection information, see the CDC NHSN webpage (https://www.cdc.gov/nhsn/index.html). Weekly hospitalization data are defined as Sunday through Saturday.