Surveillance Reports

Novel Coronavirus (COVID-19) Surveillance Update

There are two main indicators of potential COVID-19 activity locally— the number of confirmed cases and the general number of people experiencing severe respiratory illness. Seeing important increases helps our healthcare providers and partners know when COVID-19 activity may be increasing in Marin. Marin County Public Health receives regular updates on cases of respiratory illness from all Marin County emergency departments (ED), and from Emergency Medical Services (EMS), our countywide 911 ambulance response system. We track these over time, and compare to prior years. Note there’s always ups and downs in our usual activity, and we’re looking for significant changes.

Information about confirmed cases is updated daily at approximately 5:30pm Pacific Standard Time (PST). Information about respiratory illness activity is updated biweekly each Tuesday and Friday.

Confirmed COVID-19 Cases

Some of the confirmed COVID-19 cases are a result of community transmission, meaning that these cases are unrelated to travel and have no identifiable contact with a known case, indicating likely infection within our community.

 

Respiratory Illness Activity+

Common symptoms of COVID-19 include fever, cough, and difficulty breathing. Respiratory illness activity will capture visits that may be due to COVID-19 and influenza-like illnesses. The majority of individuals with COVID-19 will experience mild to moderate symptoms. However, some individuals may experience more severe symptoms and require a higher level of medical care through EMS or the ED. Tracking the total number of visits and those due to respiratory illnesses provides a situational awareness of current resource needs in our community. Each daily count below reflects 3-day rolling averages. Figures 1-3 display information on current trends in EMS calls and ED visits due to respiratory illnesses total and by age.

Utilization Trends: Over the past week, the number of ED and EMS visits and those due to respiratory illnesses have been somewhat lower than daily averages seen in January-March, 2019. Marin County Public Health will continue to monitor trends to identify any significant changes (Figures 1A-B).

Figures 1A-B: Number of Total Visits and Visits due to Respiratory Illnesses

Total Marin County Emergency Medical Services Calls (1A

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Total Kaiser San Rafael, MarinHealth Medical Center and Novato Community Hospital Emergency Department Visits* (1B

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*Discharge data from Kaiser San Rafael, MarinHealth and Novato Community Hospital show trends in ED visits due to respiratory illnesses and are updated as soon as data are available.

Percentage of visits due to respiratory illnesses: Approximately 9% of Emergency Medical Services (EMS) calls and 8% of Emergency Department (ED) visits were due to respiratory illnesses (Figures 2A-B).

Figures 2A-B: Daily Proportion of Visits due to Respiratory Illnesses

Percentage of Marin County Emergency Medical Services Calls (2A

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Percentage of Kaiser San Rafael, MarinHealth Medical Center and Novato Community Hospital Emergency Department Visits* (2B)  

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*Discharge data from Kaiser San Rafael, MarinHealth and Novato Community Hospital show trends in ED visits due to respiratory illnesses and are updated as soon as data are available.

Age Distribution of Respiratory Illness Visits: The majority of respiratory illness-related EMS calls occur among those 65 years and older, while the majority of ED visits due to respiratory illnesses occur among those less than 65 years of age (Figures 3A-B). 

Figures 3A-B: Total Visits Daily due to Respiratory Illnesses by Age

Total Marin County Emergency Medical Services Calls by Age (3A)

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Total Kaiser San Rafael, MarinHealth Medical Center and Novato Community Hospital Emergency Department Visits by Age* (3B)

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*Discharge data from Kaiser San Rafael, MarinHealth and Novato Community Hospital show trends in ED visits due to respiratory illnesses and are updated as soon as data are available.

National and Statewide COVID-19 Activity

Visit the California Department of Public Health's COVID-19 website for updates on activity statewide and the Centers for Disease Control and Prevention's website for information on nationwide activity.

+Definitions and Terminology

Respiratory illnesses are identified using free-text chief complaint and structure primary impression fields in routinely collected Emergency Medical Services and Emergency Department data. Visits that mention at least one of the following (including common misspellings) were classified as those due to respiratory illnesses for the purposes of routine surveillance: influenza-like illness, influenza, fever, shortness of breath (only if with fever in ED), difficulty breathing, respiratory distress, pneumonia, cough (only if with fever in ED), sore throat, wheezing, bronchitis.