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Novel Coronavirus (COVID-19) Activity
Issue 13 - April 24, 2020
The Marin County Department of Health and Human Services is conducting on-going surveillance of respiratory illness in Marin County to increase sensitivity in detecting potential COVID-19 activity. We will provide timely surveillance updates at marinhhs.org/coronavirus/data.
There are two main indicators of potential COVID-19 virus transmission locally — the number of confirmed cases and the number of people experiencing severe respiratory illness. Tracking this will help our healthcare providers and partners know when COVID-19 activity may be increasing in Marin. Marin County Public Health receives regular updates on respiratory illness cases 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 evaluate these trends by age because older adults infected with COVID-19 experience more severe disease. Knowing there's always ups and downs in our usual activity, we're looking for significant changes.

We have recently updated our surveillance webpage to present case information by geographic area, demographic, and clinical outcomes, including daily reports of the number of people hospitalized and in the ICU in Marin County hospitals.
As of April 24th, 212 cases of Coronavirus Disease 2019 (COVID-19) have been identified and 153 individuals have recovered. The level of respiratory illness activity in Marin County has continued to remain low with a sustained decrease in utilization of emergency care. For additional information on current activity and Marin County's response visit marinhhs.org/coronavirus. Respiratory illness and COVID-19 surveillance updates will be available at marinhhs.org/coronavirus/data.
Confirmed COVID-19 Cases:  As of April 24th, there have been 212 cases of COVID-19 diagnosed, 153 of whom have recovered*, 41 reported cumulative hospitalizations, and 12 reported deaths in Marin County. The average age of confirmed COVID-19 cases is 54 years (range: 0-101 years). Figure 1 presents positive COVID-19 tests by date of specimen collection and Figure 2 presents the number of individuals with confirmed COVID-19 who are hospitalized or in the ICU by day.

Some of these 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
*Recovered is currently defined as 14 days post-diagnosis with COVID-19 excluding deaths and those currently hospitalized.
Figure 1.  Positive COVID-19 Tests by Collection Date
Decisions to test individuals for COVID-19 are made by medical providers based on assessment of symptoms and evaluation of other possible conditions (e.g., influenza). Many providers are now performing these assessments over the telephone. Providers who determine an individual should be tested are aware that they can refer patients to Marin County Public Health to obtain testing in our drive through testing site.
Figure 2.  Number of People in a Marin Hospital or ICU with Confirmed COVID-19 by Day
Source: California Department of Health daily hospital inventory
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 3-5 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 continued to be lower than daily averages seen in January-April, 2019. All daily counts below reflect 3-day rolling averages. Marin County Public Health will continue to monitor trends to identify any significant changes (Figures 3A-B).
Figures 3A-B.  Number of Total Visits and Visits due to Respiratory Illnesses
THROUGH APRIL 23rd: Marin County Emergency Medical Services Calls (3A
THROUGH APRIL 23rd: Kaiser San Rafael, MarinHealth Medical Center and Novato Community Hospital Emergency Department Visits* (3B
*Data from Kaiser San Rafael, MarinHealth and Novato Community Hospital Emergency Departments are updated as soon as data are available.
Percentage of visits due to respiratory illnesses: Approximately 5% of Emergency Medical Services (EMS) calls and 2% of Emergency Department (ED) visits were due to respiratory illnesses (Figures 4A-B). Note that the ED trends, current and historic, reflect our recently updated respiratory illness definition.
Figures 4A-B.  Proportion of Visits due to Respiratory Illnesses
THROUGH APRIL 23rd: Marin County Emergency Medical Services Calls (4A
THROUGH APRIL 23rd: Kaiser San Rafael, MarinHealth Medical Center and Novato Community Hospital Emergency Department Visits* (4B
*Data from Kaiser San Rafael, MarinHealth and Novato Community Hospital Emergency Departments 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 5A-B). 
Figures 5A-B. Daily Age Distribution of Visits due to Respiratory Illness
THROUGH APRIL 23rd: Marin County Emergency Medical Services Calls (5A)
THROUGH APRIL 23rd: Kaiser San Rafael, MarinHealth Medical Center and Novato Community Hospital Emergency Department Visits* (5B
*Data from Kaiser San Rafael, MarinHealth and Novato Community Hospital Emergency Departments are updated as soon as data are available. Data from Kaiser San Rafael are not available at this time.

California

As of April 24th, there are 39,254 confirmed cases and 1,562 deaths in California. View full updates at the California Department of Public Health's COVID-19 website.

United States

National COVID-19 activity is continuing to increase, with 865,585 confirmed cases and 48,816 deaths across 55 states and territories (50 states, District of Columbia, Puerto Rico, Guam, the Northern Mariana Islands, and US Virgin Islands) as of April 21st. View more detailed information at the Centers for Disease Control and Prevention's COVID-19 website.
Copyright ©  2020
Marin County Department of Health and Human Services.
All rights reserved.


Lisa Santora, MD, MPH
Deputy Health Officer
(415) 473-4163

This publication is provided to you by the Office of the Public Health Officer, County of Marin Department of Health and Human Services.

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