Respiratory illness guidance for specific settings

Outbreak definitions for respiratory illness:

• COVID-19: ≥ 2 cases of probable or confirmed COVID-19 among patients 4 or more days after admission for a non-COVID condition, with epidemiologic linkage OR  ≥2 cases of suspect, probable or confirmed COVID-19 among HCP AND ≥1 case of probable or confirmed COVID-19 among patients 4 or more days after admission for a non-COVID condition, with epidemiologic linkage (source: CORHA COVID-19 definition)
• Influenza: ≥2 lab confirmed cases in patients with symptom onset ≥ 72 hours after admission, with epidemiologic linkage (source: CORHA influenza definition)
• Non-COVID-19, non-influenza, respiratory illness: ≥1 case of a laboratory-confirmed respiratory pathogen, other than influenza or COVID-19, in the setting of a cluster (≥2 cases) of acute respiratory illness (ARI)* with symptom onset ≥ 72 hours after admission

Recommendations for Prevention and Control of COVID-19, Influenza, and Other Respiratory Viral Infections in California Skilled Nursing Facilities – 2025-26

Outbreak definitions for respiratory illness:

• COVID-19: ≥2 cases of probable or confirmed COVID-19 within a 7-day period among residents, with epidemiologic linkage OR  ≥2 cases of suspect, probable or confirmed COVID-19 within a 7-day period among HCP and ≥1 case of probable or confirmed COVID-19 among residents, with epidemiologic linkage
• Influenza: ≥2 lab confirmed cases identified within a 72-hour period in residents, with epidemiologic linkage
• Non-COVID-19, non-influenza, respiratory illness: ≥1 case of a laboratory-confirmed respiratory pathogen, other than influenza or COVID-19, in the setting of a cluster (≥2 cases) of acute respiratory illness (ARI)* within a 72-hour period

CDPH general population guidance for respiratory viruses

Long-term congregate settings (e.g. RCFE, RCF, ARF)

Outbreak definitions for respiratory illness:

• COVID-19: ≥1 case of probable or confirmed COVID-19 in residents in the setting of a cluster (≥3 cases) of acute respiratory illness (ARI)* within a 7-day period
• Non-COVID respiratory illness: ≥1 case of a laboratory-confirmed respiratory pathogen, other than COVID-19, in residents in the setting of a cluster (≥3 cases) of acute respiratory illness (ARI)* within a 72-hour period

Schools, childcare, and youth programs

Report cases of acute respiratory illness* among students if:

• At least 10% of the average daily attendance of students are absent and/or reporting symptoms of acute respiratory illness (ARI) within a 7-day period (minimum of 3 cases)
• OR if there are a greater number of expected cases than usual for a given time of year
• OR if there is increased severity of illness, such as hospitalizations or fatalities among cases

CDPH Guidance for Sc​​​hool & Child Ca​re Communicable Disease Mitigation​ ​​​​

Shelters

Report cases of acute respiratory illness* among residents/staff if: 

• At least 10% of the average daily attendance of clients/staff in a cohort are reporting symptoms of acute respiratory illness (ARI) within a 7-day period (minimum of 3 cases)
• OR if there are a greater number of expected cases than usual for a given time of year
• OR if there is increased severity of illness, such as hospitalizations or fatalities among cases

* Acute respiratory illness (ARI) is defined as new onset of any two or more of the following symptoms (not better explained by chronic conditions, e.g., seasonal allergies): fever or chills, cough, sore throat, runny or stuffy nose, difficulty breathing, body aches; AND/OR has tested positive for a specific respiratory pathogen, including COVID-19, influenza, or RSV

For reporting, questions, and/or clarifications, contact the Communicable Disease Program by phone at (628) 217-6100. We are here to help!