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Coronavirus Disease 2019

Skilled Nursing Facility Guidelines for Influenza Prevention and Control in the Context of COVID-19


During the viral respiratory illness season that typically begins in late fall and continues through early spring, skilled nursing facilities (SNFs) observe an increase in the number of residents experiencing respiratory symptoms. There are many viruses that can cause respiratory illness including influenza and SARS-CoV-2 (the virus that causes COVID-19).

Optimal management of potential viral respiratory illnesses in SNFs will depend on many factors, such as detection of single or concurrent viruses and a facility’s ability to separate persons with confirmed/suspected infection(s). It can be challenging to appropriately cohort symptomatic residents and their close contacts if private rooms are not available. Managing a resident who develops acute symptoms compatible with a viral respiratory illness can be further complicated if timely access to influenza and COVID-19 testing is not available. It is not possible to provide prescriptive or standard recommendations that can be applied across all settings. Therefore, facilities must understand and adapt the principles and framework described in this document for testing and managing persons with an acute respiratory illness of suspected infectious etiology. Additionally, Los Angeles County Department of Public Health (LAC DPH) provide consultation and tailored recommendations for facilities experiencing suspect and confirmed outbreaks.

These guidelines focus on management of influenza in the context of COVID-19*. This is because influenza and SARS-CoV-2 are the viral respiratory pathogens that are associated with the greatest morbidity and mortality in the SNF population. In addition, both are vaccine preventable diseases with effective therapeutic options.

*COVID-19 specific guidance for SNFs is more fully detailed in the LAC DPH Guidelines for Preventing and Managing COVID-19 in SNFs.

Influenza Vaccination

Vaccination is the single best preventive measure. Ensuring high facility-wide influenza vaccine coverage among residents and staff can substantially reduce the risk for experiencing an influenza outbreak. Vaccination efforts should start by the end of October and should continue throughout the flu season including during outbreaks.

Facilities should ensure that all residents have received the influenza vaccine for the current season or have documentation indicating reason for declination. Facilities should establish policies and procedures to ensure that staff have received the influenza vaccine as outlined by the Health Officer Order. Starting with the 2022-2023 flu season, SNFs are required to report their healthcare personnel influenza vaccination coverage to NHSN per CMS. More details and instructions can be found here.

Please refer to the CDC Post-acute and Long-term Care Facility Toolkit: Influenza Vaccination among Healthcare Personnel for additional information and resources on influenza immunization in SNFs.

Influenza Surveillance and Outbreak Reporting

During the flu season*, a key component of influenza surveillance is actively daily symptom screening followed by prompt diagnostic testing of residents who screen positive. While daily symptom screening of SNF residents is already required for COVID-19 infection control, during the flu season, daily monitoring for signs and symptoms of acute respiratory illness serves as surveillance both for influenza and COVID-19. Prompt diagnostic testing for COVID-19 and influenza should both be immediately performed for residents with acute respiratory illness.

The symptoms of influenza and COVID-19 significantly overlap making it difficult to distinguish between the two based on symptoms alone. As a reminder, the signs and symptoms of acute respiratory illness common to both influenza and COVID-19 are fever (≥100°F or 37.8°C), cough, shortness of breath, sore throat, chills, headache, myalgia (muscle pain or body aches), fatigue (tiredness), runny or stuffy nose, vomiting, and diarrhea. Please note that some persons, such as older adults and individuals with immunocompromising conditions, may have atypical clinical presentations, including the absence of fever, for both influenza and COVID-19.

Promptly identifying influenza and/or COVID-19 will inform outbreak management decisions such as the appropriate isolation of infected residents and starting antivirals for treatment and prevention. Detection of influenza and/or COVID-19 in a facility may also indicate an outbreak, which is reportable to LAC DPH per Title 17, Section 2500, California Code of Regulations. The outbreak definition for influenza is at least two residents with acute respiratory illness within 72 hours of each other AND at least one resident has laboratory-confirmed influenza. Suspected outbreaks in SNFs must immediately be reported to LAC DPH at LACSNF@ph.lacounty.gov or ACDC-MorbidityUnit@ph.lacounty.gov as per LAC DPH Reportable Diseases and Conditions.

*While the flu season typically ranges from October through March every year, the best way for facilities to stay up to date on local influenza trends is by signing up for Los Angeles County’s influenza surveillance report “Influenza Watch”, which is sent out weekly during flu season. To sign up, email "Subscribe Flu Watch" to influenza@ph.lacounty.gov. Additionally, CDC updates national influenza surveillance data in their Weekly U.S. Influenza Surveillance Report.

Influenza Diagnostic Tests

Individuals who have signs and symptoms of acute respiratory illness are suspect for influenza as well as COVID-19 during the flu season and should immediately undergo diagnostic tests to determine if they are confirmed cases of influenza (symptomatic individuals with a positive diagnostic test), COVID-19*, or both. A variety of influenza diagnostic tests are available. It is important to understand the limitations of influenza virus tests and how to properly interpret the results. There are two categories of diagnostic tests for the detection of influenza viruses in respiratory specimens:

  1. Molecular assays including rapid molecular (viral RNA or nucleic acid) assays and laboratory-based reverse transcription polymerase chain reaction (RT-PCR).
  2. Antigen detection tests including rapid influenza diagnostic tests (RIDTs) and immunofluorescence assays.

CDC recommends using molecular assays including rapid molecular assays and laboratory-based RT-PCR for diagnostic testing in institutional outbreaks because of the low to moderate sensitivity of antigen detection assays (i.e., antigen tests have a higher likelihood of false negatives). Rapid influenza antigen detection assays can be used if rapid molecular assays are unavailable or laboratory-based molecular assay results are pending. However, negative antigen test results in symptomatic individuals must be confirmed with a molecular assay (RT-PCR) prior to discontinuing isolation.

*COVID-19 diagnostic testing is described separately in the LAC DPH Guidelines for Preventing & Managing COVID-19 in SNFs.

Influenza Outbreak Management in the context of COVID-19

Containing an influenza outbreak and mitigating morbidity depends on three key activities: 1) early identification of infected residents and staff (please see “Influenza Surveillance and Testing Strategies” above), 2) early initiation of antiviral influenza therapy for residents with suspected or confirmed influenza and chemoprophylaxis for exposed residents, and 3) optimal isolation of residents with suspected or confirmed influenza.

Early identification of influenza

All SNFs should be conducting daily proactive surveillance (symptom screening) of staff and residents as required for COVID-19 active surveillance. Daily surveillance of residents should also include temperature checks and oxygen saturation. All residents with signs and symptoms of acute respiratory illness should immediately be tested for both SARS-CoV-2 and influenza, preferably at the same time to avoid delays in diagnosis. Please see Influenza Diagnostics Tests section above for more details. If symptomatic residents test negative for both influenza and SARS-CoV-2, then consider additional viral or bacterial testing based on respiratory pathogens known or suspected of circulating in the community.

Early initiation of influenza antiviral treatment and chemoprophylaxis


All SNF residents with suspected or confirmed influenza should be started on antiviral treatment immediately and within 48 hours of symptom onset. Treatment should not be delayed pending test results for residents with strongly suspected influenza unless there is a confirmed active COVID-19 outbreak in the facility. Influenza should be strongly suspected in a resident with acute respiratory symptoms if 1) there are other persons with confirmed influenza at the facility or 2) LA County influenza surveillance data indicate that >5% of respiratory specimens tested Countywide are positive for influenza. Oseltamivir is the most commonly used antiviral medication, but other options include oral baloxavir, inhaled zanamivir, and intravenous peramivir. See CDC, Influenza Antiviral Medications: Summary for Clinicians for more information.


Chemoprophylaxis refers to the use of antiviral medications to prevent influenza in asymptomatic persons either pre- or post-exposure. Oral oseltamivir is the preferred antiviral for chemoprophylaxis, but inhaled zanamivir is also an option. Please see CDC, Influenza Antiviral Medications: Summary for Clinicians for more information. If symptoms develop, individuals should receive treatment dosing (see above).

  • Asymptomatic residents should be offered chemoprophylaxis in the following situations, regardless of vaccination history:
    • All of the roommates of a resident with confirmed influenza infection should be started on oseltamivir chemoprophylaxis.
    • If influenza infection is confirmed in a second resident who was not a roommate of the first case, antiviral chemoprophylaxis should be started for all residents in the outbreak-affected unit/wing.
    • If there are cases in multiple units/wings, then chemoprophylaxis should be provided for all residents in the facility regardless of vaccination history, with priority given to the roommates of the confirmed cases when there is a shortage of antivirals.
  • Chemoprophylaxis can be considered for asymptomatic healthcare personnel (HCP) when the facility has an outbreak of influenza in the following situations:
    • If they are unvaccinated; OR
    • If they received an inactivated influenza vaccine within 14 days prior: OR
    • If evidence indicates that the circulating influenza viruses are not well-matched to the seasonal influenza vaccine, regardless of HCP vaccination history; OR
    • If there is a risk of short staffing in facilities and units where HCP are limited and to reduce HCP reluctance to provide care to residents with suspected or confirmed influenza, regardless of HCP vaccination history.

SNFs experiencing a shortage or a low supply of oseltamivir

When there is a limited supply of oseltamivir, then the treatment of residents with suspected and confirmed influenza should be prioritized over the chemoprophylaxis of asymptomatic persons.

If there is a remaining but limited supply of oseltamivir for chemoprophylaxis, it is recommended that SNFs prioritize chemoprophylaxis for roommates of suspected/confirmed cases and consider use of inhaled zanamivir in addition to or in place of oral oseltamivir. Please see CDC, Influenza Antiviral Medications: Summary for Clinicians for more information.

Residents not receiving chemoprophylaxis as recommended (see above) should be closely monitored for the development of fever and/or respiratory symptoms. If symptoms develop, empiric therapy should be provided as soon as possible without waiting for laboratory confirmation.

Facilities should continue to secure additional supply and can utilize and/or share with their long-term care pharmacy this resource from the Food and Drug Administration (FDA): Availability of Antiviral Medications. If there are any issues or questions regarding oseltamivir supply, please do not hesitate to contact Public Health at LACSNF@ph.lacounty.gov.

Optimal isolation of residents with suspected or confirmed COVID-19 and/or influenza

Appropriate isolation of residents with suspected or confirmed influenza can be logistically challenging given the multiple permutations of residents who could have influenza, COVID-19, coinfection with both viruses, and/or infection with some other respiratory virus.


Below is a brief summary of COVID-19 isolation recommendations. For full details, please refer to Isolation and Quarantine section of the LAC DPH Guidelines for Preventing and Managing COVID-19 in SNFs.

  • Residents with confirmed COVID-19 infection should isolate in a physically separated Red Cohort. Confirmed COVID-19 is defined as symptomatic residents with a positive viral test (PCR/NAAT or antigen) or asymptomatic residents with a positive molecular (PCR/NAAT) test.
  • Residents with suspected COVID-19 should isolate in-place in their current rooms. Suspected COVID-19 are symptomatic residents with pending/unknown test results or asymptomatic residents with a positive antigen test pending confirmatory PCR/NAAT testing.
  • Asymptomatic residents who are close contacts or who were in the same unit or wing where an individual with infectious COVID-19 was identified should remain in their current rooms unless sufficient private rooms are available. They no longer need to be quarantined unless directed by Public Health during an active COVID-19 outbreak investigation.


The guidance for isolation for influenza differs from COVID-19 because compared with COVID-19, influenza tends to be less contagious, the morbidity is lower, and there are antivirals authorized as chemoprophylaxis to mitigate influenza spread.

For confirmed cases of influenza in residents (symptomatic with positive diagnostic test results), unlike COVID-19, it is not necessary for facilities to dedicate a physically separated space for isolation. Facilities should consider isolating residents with confirmed influenza in a private room, if possible. However, if a private room is unavailable, then the resident with influenza and their roommates should remain in their current rooms on droplet transmission based precautions in addition to standard precautions. In multi-occupancy rooms, ensure spatial separation of at least 6 feet and privacy curtain between residents. In facilities that do not have 6 feet of space between residents, separation should be as close to 6 feet as possible, but no less than 3 feet. Duration of droplet precautions is at least 7 days from illness onset or until improvement in symptoms and fever free for at least 24 hours without fever reducing medications, whichever is longer. Hospitalized patients with influenza can be discharged to a SNF when clinically appropriate and should be continued on droplet cautions; the duration of droplet precautions is the same as above and does not need to be restarted upon admission to the SNF.

Symptomatic residents who are waiting for influenza testing results should be isolated on the most protective transmission based precautions, preferably in private rooms if available. However, if a private room is unavailable, then the symptomatic resident and their roommates should isolate in-place remaining in their current rooms on the most protective transmission based precautions. Subsequent management will follow either the COVID-19 or influenza guidance as indicated by the testing results.

In general, avoid moving residents with suspected or confirmed influenza to different rooms that could lead to new exposures.

Other Outbreak Control Measures
Managing Healthcare Personnel During an Influenza Outbreak

Facilities should encourage staff to get the influenza vaccine if they have not already received it. Influenza infected staff should be excluded from work for at least 7 days after symptom onset or >24 hours after fever resolution (without antipyretics) and improvement of respiratory symptoms. Staff with suspect or confirmed influenza should promptly seek medical care to determine if antiviral treatment is appropriate, regardless of vaccination history. Asymptomatic staff may be offered antiviral chemoprophylaxis if indicated as described above.

Personal Protective Equipment (PPE)

In the context of the current COVID-19 pandemic, standard precautions and source control are required for caring for all SNF residents, regardless of the presence of influenza. When caring for residents with a new acute respiratory illness, an N95 respirator should be worn as a part of COVID-19 transmission based precautions until test results are returned and COVID-19 is excluded. See Infection Prevention and Control Guidance section of the LAC DPH Guidelines for Preventing and Managing COVID-19 in SNFs for more information.

Source Control

In addition to required use of face masks by healthcare personnel and visitors, residents are strongly encouraged to wear well-fitting face masks when they are outside their room throughout the flu season.


There are currently no general restrictions to visitation for either influenza or COVID-19 outbreaks in SNFs. Visitors should be made aware of any outbreaks occurring at the facility, including influenza and COVID-19. Facilities can do this by posting signage at entrances and sending out communication (letters, emails, texts) to families and visitors. They should also be counseled on their risks of visiting residents who are suspect or confirmed cases of influenza or COVID-19 and should follow healthcare personnel instruction on proper donning and doffing of PPE when applicable. Additional COVID-19 guidance for visitors may apply; please see the Communal Dining, Group Activities, and Visitation section of the LAC DPH Guidelines for Preventing and Managing COVID-19 in SNFs.

Concurrent COVID-19 and Influenza Outbreak Management

If there are concurrent COVID-19 and influenza outbreaks, then the facility should prioritize implementing isolation, PPE use, and other infection control precautions as recommended for COVID-19. If a resident is concurrently diagnosed with COVID-19 and influenza by molecular testing for both viruses, then the resident should ideally be placed in a private room in the COVID-19 Red Cohort. If there are not sufficient private rooms in the Red Cohort, then consider cohorting “like with like,” i.e., place residents who are co-infected with both influenza and COVID-19 in the same room. However, if this is also not possible and in general, avoid the movement of residents that could lead to new exposures. The rationale behind prioritization of isolation of residents and staff by COVID-19 status over influenza status is because influenza tends to be less contagious, the morbidity and mortality is lower, and there are more approved pharmacological interventions for mitigating outbreaks of influenza.

Residents who are suspected or confirmed to have co-infections of influenza and COVID-19 should be started on antiviral treatments for both. Influenza antiviral treatment should be started as soon as possible and within 48 hours of symptom onset, even before testing confirmation when suspicion is high (empiric treatment). COVID-19 antivirals, e.g., ritonavir-boosted nirmatrelvir (Paxlovid), should be started in symptomatic persons as soon as testing results confirm infection and within 5 days of symptom onset. Please see Outpatient COVID-19 Treatment and Pre-exposure Prophylaxis in the LAC DPH Guidelines for Preventing & Managing COVID-19 in SNFs for more details. LAC DPH’s COVID-19 Therapy for Non-Hospitalized Patients for healthcare providers is another helpful resource. Antiviral regimens for influenza treatment are the same for all individuals regardless of SARS-CoV-2 co-infection.

Please note that while Paxlovid can alter the concentration of some drugs, there are no clinically significant drug-drug interactions between the outpatient treatment options for COVID-19 and the influenza antiviral agents. In addition, Paxlovid can be safely co-administered with many commonly used medications despite its drug-drug interaction potential. The Infectious Disease Society of America offers guidance on simple steps that can be taken to avoid significant interactions with commonly prescribed medications, such as brief suspension or dose reduction. See NIH guidance Drug-Drug Interactions Between Ritonavir-Boosted Nirmatrelvir (Paxlovid) and Concomitant Medications and the Liverpool COVID-19 Drug Interactions website.

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Public Health has made reasonable efforts to provide accurate translation. However, no computerized translation is perfect and is not intended to replace traditional translation methods. If questions arise concerning the accuracy of the information, please refer to the English edition of the website, which is the official version.

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