Respiratory illness guidance for specific settings

Acute Care Hospitals (ACHs)

Outbreak definitions for respiratory illness (see CORHA COVID-19 and influenza definitions for more details):

• 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
• Influenza: ≥2 lab confirmed cases in patients with symptom onset ≥ 72 hours after admission, 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) with symptom onset ≥ 72 hours after admission

Skilled Nursing Facilities (SNFs)

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

Non-healthcare settings (e.g. RCFE, RCF, ARF)

CDPH general population guidance for respiratory viruses

Outbreak definitions for respiratory illness:

• COVID-19: ≥1 case of probable or confirmed COVID-19 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 the setting of a cluster (≥3 cases) of acute respiratory illness (ARI) within a 72-hour period

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