When should testing for influenza (flu) and Coronavirus Disease 2019 (Covid-19) be initiated in long-term care settings?

When to Test for Flu and COVID-19 in Long-Term Care Settings

Implement active surveillance and test immediately when any resident presents with respiratory symptoms, atypical presentations (diarrhea, falls, delirium, temperature changes), or behavioral changes—and initiate outbreak control measures as soon as one laboratory-confirmed case is identified in the facility. 1, 2

Routine Surveillance Testing (No Active Outbreak)

Weekly testing of all residents and staff for COVID-19 should be performed when there are no active outbreaks, particularly during periods of community transmission. 2

• Test all asymptomatic residents and staff weekly using nasopharyngeal swabs for SARS-CoV-2 via RT-PCR or rapid antigen tests 2
• Continue routine surveillance throughout influenza season and periods of COVID-19 community transmission 2
• Test symptomatic staff immediately before allowing facility entry 2

Immediate Testing Triggers for Individual Residents

Test any resident immediately who presents with ANY of the following, regardless of whether they appear "typical" for respiratory infection: 1, 2, 3

Classic Respiratory Presentations:

• New or worsening cough (with or without fever) 1, 2
• Shortness of breath or oxygen desaturation 1, 2
• Sore throat 2
• Tachypnea (>25 respirations/minute) 1

Atypical Presentations (Critical—Often Precede Respiratory Symptoms):

• Diarrhea (may precede respiratory symptoms by several days in 26% of COVID-19 cases) 1, 3
• Falls (occurred in 18% before respiratory symptoms developed) 3
• Temperature changes including hypothermia (34% presented with fluctuating temperature) 3
• Delirium or behavioral changes 1, 2, 3
• New loss of taste or smell (anosmia/ageusia) 1, 2

Non-Specific Systemic Symptoms:

• Fever, chills, or temperature elevation 1, 2
• Headache, muscle pain, or joint pain 2
• Fatigue or weakness 2

Outbreak Threshold and Response

For Influenza: 1

• Implement active surveillance immediately when one laboratory-confirmed influenza case is identified 1
• Initiate full outbreak control measures (including antiviral chemoprophylaxis) when two healthcare-associated laboratory-confirmed influenza cases occur within 72 hours on the same ward/unit 1
• Consider implementing outbreak measures if one or more residents have suspected influenza and molecular testing results are not available same-day 1

For COVID-19: 2

• Increase testing frequency to every 3 days once a single COVID-19 case is identified 2
• Test all residents in the same compartment as the index case 2
• Implement heightened surveillance across all facility compartments 2

During Confirmed Outbreaks

Test any resident with even minimal symptoms during an identified outbreak: 1, 2

• Test for acute respiratory symptoms with or without fever 1
• Test for temperature elevation OR reduction (not just fever) 1
• Test for behavioral changes even without respiratory symptoms 1
• Do not wait for test results to initiate empiric antiviral treatment 1

Dual Testing Strategy

Test simultaneously for both COVID-19 and influenza when community transmission of both pathogens is occurring. 2

• Use combined testing approach for any resident with respiratory or atypical symptoms during overlapping transmission periods 2
• This prevents missed diagnoses and allows appropriate isolation and treatment decisions 2

Specimen Collection Best Practices

For Influenza: 1

• Obtain nasopharyngeal swab (simpler with acceptable sensitivity) within 24-48 hours of symptom onset 1
• Combine throat and nasopharyngeal swabs in single refrigerated tube with viral transport media 1
• Transport on ice within 1-2 hours to experienced laboratory for viral culture and rapid diagnostic testing 1

For COVID-19: 2

• Use nasopharyngeal swabs for RT-PCR or rapid antigen testing 2
• Collect specimens promptly when symptoms are identified 2

Critical Pitfalls to Avoid

Do not rely solely on "classic" respiratory symptoms—atypical presentations are common and may be the only early warning sign in long-term care residents. 3

• Waiting for fever and cough can delay diagnosis by days, during which rapid transmission occurs (48% facility-wide infection rate documented when atypical presentations were missed) 3
• Hypothermia is as important as fever in this population 3
• Diarrhea, falls, and delirium may be the only initial symptoms before respiratory involvement develops 3
• Do not delay testing for influenza beyond 48 hours of symptom onset, as viral isolation success decreases significantly 1
• Rapid antigen tests for influenza have only 40-80% sensitivity in elderly adults, so negative results should not rule out infection in high-risk situations 1