Influenza Management

Principles of Therapy

Management Decision

The initial management of influenza in adults is based on clinical presentation and epidemiological data. 

Seasonal Influenza*  

Seasonal influenza may present as a mild respiratory illness similar to the common cold or it may present without any characteristic signs and symptoms. Diagnosis based on typical symptoms may be difficult because other pathogens cause similar symptoms (eg coronavirus disease 2019 [COVID-19], respiratory syncytial virus, rhinovirus, parainfluenza virus). Identification is made easier when it is known that the influenza virus is present in the community. 

Course of Illness  

The course of illness for uncomplicated influenza typically resolves for most patients after 3 to 7 days. Cough and malaise can persist for more than 2 weeks.  

*Please see Etiology and Laboratory Tests and Ancillaries for further information.

Avian Influenza*  

During the initial stages of illness that are caused by avian influenza infection, the clinical examination does not accurately distinguish it from other causes of community-acquired pneumonia, influenza-like illness, acute gastroenteritis, or acute encephalitis.  

Course of Illness  

The course of illness of avian influenza often presents as a rapidly progressive pneumonia with respiratory failure ensuing over several days. Hospital care is warranted for patients with significant dehydration and those with respiratory distress, hypoxemia, impaired cardiopulmonary function, or altered mental status. Admission for observation may also be warranted for patients with increased risk for complications. The incubation period for human H5N1 and H7N9 infection following exposure to infected poultry is ≤7 days and is often 2-5 days.  

Risk Stratification  

High-risk exposure groups are currently defined as household or close family contacts of a strongly suspected or confirmed H5N1 patient because of potential exposure to a common environmental or poultry source as well as exposure to the index case.  

Moderate-risk exposure groups are currently defined as personnel handling sick animals or decontaminating affected environments (including animal disposal) if personal protective equipment is not used properly. Individuals with unprotected and very close direct exposure to sick or dead animals infected with the H5N1 virus or to particular birds that have been directly implicated in human cases are likewise considered under moderate-risk exposure groups. Healthcare personnel in close contact with strongly suspected or confirmed H5N1 patients such as during intubation or performing tracheal suctioning, delivering nebulized drugs, or handling inadequately screened or sealed body fluids without any or with insufficient personal protective equipment is also under moderate-risk exposure groups. This group also includes laboratory personnel who might have unprotected exposure to virus-containing samples.  

Low-risk exposure groups are currently defined as healthcare workers not in close contact (distance >1 m) with a strongly suspected or confirmed avian influenza patient and having no direct contact with the infectious material from that patient. Healthcare workers who used appropriate personal protective equipment during exposure to infected patients, personnel involved in culling non-infected or likely non-infected animal populations as a control measure, and personnel involved in handling sick animals or decontaminating affected environments (including animal disposal), who used proper personal protective equipment are also considered as low-risk exposure groups.  

*Please see Etiology and Laboratory Tests and Ancillaries for further information.

Pharmacological therapy

Symptomatic Therapy

Fever and myalgia may be treated with analgesics (non-opioids) and antipyretics (eg Paracetamol). Avoid salicylates in children ≤18 years of age because of the risk of Reye’s syndrome. Cough and colds may be treated with cough and cold preparations (eg expectorants, mucolytics).  

Antivirals for Seasonal Influenza

Prophylaxis

Antivirals used for prophylaxis for seasonal influenza include Baloxavir, Oseltamivir, and Zanamivir. Antiviral agents may be used to prevent the spread of influenza among unvaccinated high-risk household members within 48 hours of contact with a person with influenza, and during an influenza outbreak in an institutionalized setting. 

They may be used in persons who cannot be vaccinated due to contraindications to the vaccine and do not start until the influenza epidemic has begun and stop only when the epidemic is over. They may also be used in persons at high risk for complications who have been vaccinated after an outbreak of influenza begun but should be given for 2 hourly starting from the day of vaccination to give sufficient time for immunity to develop. They may be given to asymptomatic persons who are at extremely high risk (ie >85 years old with or without risk factors for severe disease or younger patients with multiple risk factors) for severe illness if they contact influenza or have been exposed to seasonal influenza viruses in the past 48 hours.

Treatment 

Empirical antiviral treatment should be started as soon as possible for all patients with suspected influenza who have progressive, complicated or severe disease, are hospitalized, or are at high risk for influenza complications, regardless of illness duration and even without confirmed influenza test results. When used within 48 hours of symptom onset, antiviral agents may reduce the duration of symptoms and reduce the risk of influenza complications. They should not be used if there is uncertainty about the diagnosis or if a bacterial infection cannot be ruled out. Giving antibiotics to patients with suspected or confirmed non-severe influenza infection when there is low probability of bacterial co-infection is not recommended. Empiric antibiotic therapy may be considered in patients presenting with respiratory failure and/or hemodynamic instability, those who fail to improve or clinically deteriorate after 3-5 days of antiviral therapy and supportive care. Optimal dosing and duration of antiviral therapy should be individualized according to patient’s clinical circumstances. A longer daily dosing of oral Oseltamivir or IV Peramivir for hospitalized patients with influenza who continue to be severely ill after 5 days of treatment should be considered. A longer duration of treatment may be necessary in immunocompromised patients or critically ill patients with respiratory failure who may have prolonged influenza viral replication.
 
Baloxavir marboxil 

Baloxavir marboxil is the first approved influenza virus-specific enzyme polymerase acidic (PA) protein-targeting drug used for the treatment of acute uncomplicated seasonal influenza (A and B viruses) in patients ≥12 years old who exhibited symptoms for no more than 48 hours and are at high risk of developing influenza complications. It may also be used as a single-dose post-exposure prophylaxis agent in children ≥12 years of age. Based on several studies, the therapeutic effect of a single dose of Baloxavir marboxil is comparable to that of the 5-day twice-daily treatment with Oseltamivir. Baloxavir may be considered in patients at high risk of progression to severe illness (≥65 years old or with one or more risk factors [immunocompromise, chronic illness]). However, it should not be used for treatment of immunocompromised patients as its use has been associated with emergence of resistance. 

M2 Inhibitors

Example drugs: Amantadine, Rimantadine  

M2 inhibitors are active against influenza A viruses, but not against influenza B viruses. High resistance to adamantanes is continuing among influenza A (H3N2) and influenza A (H1N1) pdm09 viruses. Thus, Amantadine and Rimantadine are not recommended for treatment and chemoprophylaxis of currently circulating influenza A viruses.  

Its effect as a treatment is apparent when used within 48 hours of illness onset in otherwise healthy adults as it can reduce the duration of uncomplicated influenza. As chemoprophylaxis, both drugs are 70-90% effective in preventing illness from influenza A infection. They prevent illness while allowing subclinical infection and the development of protective antibodies. Additionally, therapy does not interfere with the antibody respiratory response to the vaccine.  

The incidence of central nervous system (CNS) side effects is higher among persons taking Amantadine than those taking Rimantadine.  

Neuraminidase Inhibitors

Example drugs: Oseltamivir, Peramivir, Zanamivir  

Oral Oseltamivir and inhaled Zanamivir are used for the treatment and prophylaxis of infection with influenza A or B viruses. It is recommended to give Oseltamivir (oral or enterically administered) to hospitalized patients, those with progressive, complicated or severe disease who are not hospitalized, and those at high risk for influenza complications. Zanamivir is contraindicated in patients with asthma or COPD due to the risk of bronchospasm. IV Peramivir is used for the treatment of influenza A and B viruses, especially for those who are intolerant to oral medications and to enterically administered Oseltamivir. Combination treatment with neuraminidase inhibitors is not recommended. Inhaled Laninamivir may also be used for influenza, but its use is limited by its availability as it is only available in Japan.
 
As a treatment, they can reduce the duration of uncomplicated influenza A and B illness by approximately 1 day compared with a placebo when used within 2 days of illness onset. Both drugs are effective, 82% Oseltamivir and 84% Zanamivir, in preventing febrile, laboratory-confirmed influenza illness in otherwise healthy individuals. As chemoprophylaxis, the experience in preventing the spread of influenza within institutions is limited when compared to the M2 inhibitors.

Antivirals for Avian Influenza

Prophylaxis  

Antivirals for prophylaxis for avian influenza include Baloxavir marboxil, Oseltamivir, and Zanamivir. They are given within 48 hours of exposure to zoonotic influenza associated with high risk of mortality or unknown risk for severe disease (ie H5N1, H7N9). In high-risk exposure groups, including pregnant women, Oseltamivir should be administered as chemoprophylaxis continuing for 7-10 days after the last exposure. Zanamivir could be used in the same way as an alternative. In low-risk exposure groups and pregnant women, chemoprophylaxis is not recommended. In areas where neuraminidase inhibitors are not available, Amantadine or Rimantadine might be administered for chemoprophylaxis if local surveillance data show that the virus is known or likely to be susceptible to these drugs among high- or moderate-risk exposure groups. In low-risk exposure groups and pregnant women, Amantadine and Rimantadine should not be administered for chemoprophylaxis. In pregnant women, Amantadine and Rimantadine should not be administered for chemoprophylaxis as well. In the elderly, people with impaired renal function, and individuals receiving neuropsychiatric medication, or with neuropsychiatric or seizure disorders, Amantadine should not be administered for chemoprophylaxis.  

Treatment  

It is recommended that treatment with a neuraminidase inhibitor is started as early as possible in the clinical course. Initiation of treatment should occur simultaneously with testing; laboratory confirmation is not required prior to treatment. Treatment should still be initiated even 48 hours after illness onset. Data regarding the effectiveness of these antiviral medications against H5N1 infections is limited. 

M2 Inhibitors  

Example drugs: Amantadine, Rimantadine  

Early Amantadine treatment of patients with adamantane-susceptible influenza A(H5N1) virus infections in Hong Kong in 1997 may have been associated with clinical benefit. They are not recommended for patients with avian influenza A(H7N9) virus infection and should only be considered in H5N1 influenza as a treatment option if with treatment failure after neuraminidase inhibitors.  

Neuraminidase Inhibitors  

Example drugs: Oseltamivir, Peramivir, Zanamivir  

Oseltamivir is the primary antiviral agent of choice for the treatment of influenza A(H5N1) and A(H7N9) virus infections. It is the preferred agent for hospitalized patients. The cultivable virus generally disappears within 2 to 3 days after initiation of Oseltamivir among avian influenza survivors, although clinical progression has been reported. The standard duration of therapy is 5 days but may be extended to 10 days if with no clinical improvement. It is highly active in vitro and in animal models, including those that are due to the Oseltamivir-resistant influenza A(H5N1) virus.

Orally inhaled Zanamivir has low systemic absorption and may not be useful if extrapulmonary dissemination has occurred. It is considered for patients who cannot tolerate oral therapy. Intravenous Zanamivir may be considered for inpatients with suspected or confirmed resistance to Oseltamivir and Peramivir therapy. Zanamivir monotherapy is associated with a rapid emergence of resistance.  

They may be used as an off-label treatment option in patients with confirmed or strongly suspected infection if Oseltamivir is unavailable especially if the virus is known or likely to be susceptible.

Influenza_Management 1

Nonpharmacological

Rest is recommended for patients with influenza. Strenuous physical activities (eg running) should be avoided until complete recovery. Patients are advised not to go to work or school and to avoid crowded places to reduce transmission. They may return to full activity gradually after the illness has resolved, especially if it has been severe. 

Advise patients to wear masks in public areas, cover their nose or mouth when coughing or sneezing, and perform frequent hand washing. Advise patients that adequate fluid intake is necessary to prevent dehydration and that adequate nutrition will assist in recovery. Advise the patient, if necessary, to stop smoking.

Supportive Therapy for Hospitalized Patients

Oxygen (O2) Therapy  

Administer O₂ by face mask rather than nasal prongs. The goal is to maintain >80 mmHg partial arterial pressure of O₂ (PaO₂) and >90% (95% for pregnant women) O₂ saturation (SaO₂).  

Continuous O₂ therapy is indicated for patients with PaO₂ of <80 mmHg, hypotension, metabolic acidosis with bicarbonate of <18 mmol/L, or respiratory distress with a respiratory rate of >24 breaths per minute.  

As a caution, the use of nebulizers and high airflow O₂ masks has been potentially implicated in the nosocomial spread of severe acute respiratory syndrome. Use these measures only if clinically justified and apply them under strict infection control including airborne transmission precautions. 

Hydration and Nutrition  

It is vital to assess volume depletion in patients with influenza and consider administering intravenous (IV) fluids if necessary. Patients who are hospitalized for prolonged periods may require increased nutritional support (enteral, parenteral). 

Prevention

Influenza Vaccines

The following recommendations apply to seasonal influenza only; vaccines against avian influenza are still being developed.  

Vaccines are the primary preventive measure against influenza, and it decreases morbidity and mortality caused by influenza. It is vital in reducing the impact of influenza-related respiratory illnesses on the population and resulting burdens on the healthcare system during the COVID-19 pandemic. Vaccines used should comply with the current WHO recommendations.  

Routine influenza vaccination should be given annually to persons ≥6 months old with no contraindication/s to any of its components. An age-appropriate formulation of inactivated influenza vaccine (IIVs), recombinant influenza vaccine (RIV), or live attenuated influenza vaccine (LAIV) should be given. 

Vaccines may be trivalent, containing two type A strains and one type B strain of influenza, or quadrivalent, containing two type A strains and two type B strains of influenza. Patients aged ≥65 years should preferentially receive high-dose IIV, RIV, or aIIV, while high-dose IIV and aIIV are preferred for solid organ transplant recipients aged 18–64 years who are on immunosuppressive medication. If the preferred vaccines are not available, age-appropriate vaccines should be used instead.

Special populations that may be given the influenza vaccine include those with a history of egg allergy who only have hives after exposure, those with a history of egg allergy other than hives (ie angioedema, lightheadedness, recurrent emesis, respiratory distress, and those who required Epinephrine or other emergency medical intervention), and pregnant women including those who want to become pregnant.  

Influenza vaccines should be administered in settings in which personnel and equipment needed for rapid recognition and treatment of acute hypersensitivity reactions are readily available. A history of severe allergic reaction (eg anaphylaxis) with any form of influenza vaccine is a contraindication for future receipt of all egg-based IIV and LAIV. Any previous severe allergic reaction to any egg-based IIVs, RIV or LAIV is a precaution for using cell-based IIVs. If administered, the occurrence of severe allergic reaction to cell culture-based IIV and RIV is a contraindication for future receipt of the same vaccine.

Travelers who would want to reduce the risk of influenza may receive influenza vaccination at least 2 weeks prior to departure. A history of influenza vaccination does not exclude the possibility of influenza virus infection in a patient presenting with signs and symptoms suggestive of influenza. It is acceptable to administer any IIV4 or RIV4 to individuals receiving antiviral drugs for treatment or prophylaxis of influenza.

Composition  

For the 2025/2026 northern hemisphere flu season, the recommended egg-based trivalent vaccine should contain an A/Victoria/4897/2022 (H1N1)pdm09-like virus, A/Croatia/10136RV/2023 (H3N2)-like virus, and a B/Austria/1359417/2021 (B/Victoria lineage)-like virus. Quadrivalent vaccines will contain the mentioned three viruses, plus a B/Phuket/3073/2013 (B/Yamagata lineage)-like virus.
 
For the 2025/2026 northern hemisphere flu season, the recommended cell culture- or recombinant-based protein- or nucleic acid-based trivalent vaccine should contain an A/Wisconsin/67/2022 (H1N1)pdm09-like virus, an A/District of Columbia/27/2023 (H3N2)-like virus, and a B/Austria/1359417/2021 (B/Victoria lineage)-like virus. Quadrivalent vaccines will contain the mentioned three viruses, plus a B/Phuket/3073/2013 (B/Yamagata lineage)-like virus. 
 
For the 2025 southern hemisphere flu season, the recommended egg-based trivalent vaccine should contain an A/Victoria/4897/2022 (H1N1)pdm09-like virus, an A/Croatia/10136RV/2023 (H3N2)-like virus, and a B/Austria/1359417/2021 (B/Victoria lineage)-like virus. Quadrivalent vaccines will contain the mentioned three viruses, plus a B/Phuket/3073/2013 (B/Yamagata lineage)-like virus.
 
For the 2025 southern hemisphere flu season, the recommended cell- or recombinant protein- or nucleic acid-based trivalent vaccine should contain an A/Wisconsin/67/2022 (H1N1)pdm09-like virus, an A/District of Columbia/27/2023 (H3N2)-like virus, and a B/ Austria/1359417/2021 (B/Victoria lineage)-like virus. Quadrivalent vaccines will contain the mentioned three viruses, plus a B/Phuket/3073/2013 (B/Yamagata lineage)-like virus. 

Inactivated Influenza Vaccine (IIV)  

Examples of IIV include trivalent IIV, quadrivalent IIV, adjuvanted trivalent vaccine, and adjuvanted inactivated quadrivalent vaccine. IIV is given intramuscularly and contains killed or inactivated viruses (egg-based or cell culture-based), so it cannot cause influenza. It is licensed for use among persons aged >6 months, including those who are healthy and those with chronic medical conditions. High-dose IIV is preferred for people ≥65 years of age.

In terms of effects, if the vaccine used contains the predominant circulating influenza strains, it can be 70-90% effective in preventing illness in healthy adults aged <65 years. It is approximately 50-77% effective when the vaccine strains were antigenically dissimilar to the majority of circulating strains.            

Patients with concurrent medical conditions may have a reduced rate of severe respiratory illness and death (up to 50%). The main benefit of vaccination in these patients is the prevention of severe consequences of infection rather than preventing uncomplicated illness. Vaccines that conform to international standards of purity and potency are usually free from systemic side effects. 

Recombinant Influenza Vaccine (RIV)  

Examples of RIV include trivalent RIV and quadrivalent RIV. RIV is an approved influenza vaccine that is neither inactivated nor weakened. It is recommended for patients aged ≥9 years. It uses recombinant DNA technology and an insect virus expression system to produce an egg protein-less vaccine against seasonal influenza. 

Live Attenuated Influenza Vaccine (LAIV4)  

Examples of LAIV include trivalent LAIV and quadrivalent LAIV. It is an egg-based vaccine that is given intranasally and contains live attenuated viruses that may cause mild signs and symptoms. It is licensed for use among non-pregnant persons aged 2-49 years without contraindications (eg anatomic and functional asplenia, cerebrospinal fluid leak, cochlear implants), including healthcare personnel and other close contacts of high-risk persons (except severely immunocompromised persons who require care in a protected environment). It may be used postpartum.  

In terms of effects, it significantly reduces the incidence of severe febrile illnesses, number of sick days, frequency of physician visits, and antibiotic use. Effects include a 55% reduction in culture-confirmed influenza among children who received LAIV compared with those who received IIV, a 52% greater efficacy than TIV in preventing influenza among children aged 6-71 months who had previously experienced recurrent respiratory tract infection, and a 32% increased protection in preventing culture-confirmed influenza in children and adolescents aged 6-17 years with asthma.  

LAIV should not be used in children and adolescents who are receiving Aspirin or salicylate-containing products, persons who have experienced severe allergic reactions to the vaccine or any of its components and previous dose of any influenza vaccine, pregnant women, immunosuppressed children and adults (includes immunosuppression caused by medication and human immunodeficiency virus [HIV]), caregivers and close contacts of immunocompromised individuals who require a protected environment, children 2 to 4 years with asthma or with a wheezing episode; and persons who took Oseltamivir and Zanamivir within the previous 48 hours, Peramivir within the previous 5 days, or Baloxavir within the previous 17 days.
 
Coadministration with Other Vaccines  

Influenza vaccines may be administered simultaneously or sequentially with other inactivated or live vaccines. LAIV4 may be administered simultaneously with other inactivated or live vaccines. For live vaccines given sequentially, an interval of at least 4 weeks is recommended. Current guidelines indicate that COVID-19 vaccines can be administered with influenza vaccines. IIVs and RIVs may be given at the same time as COVID-19 vaccines but should be administered on another site.

Influenza_Management 2

• Patients who have been fully vaccinated and with no known recent exposure to individuals with suspected or confirmed COVID-19 infection may proceed to receive the influenza vaccine
• Influenza vaccine may be given to patients in quarantine due to close contact exposure with a COVID-19-positive individual if another opportunity to be vaccinated is not likely; vaccination may be deferred until quarantine has been completed if possible symptoms of COVID-19 infection may cause diagnostic confusion
• Vaccination should be delayed for symptomatic individuals with suspected or confirmed COVID-19 infection until the criteria to discontinue isolation is fulfilled (at least 10 days after symptom onset and 24 hours afebrile without the use of fever-reducing medications) and COVID-19 symptoms are improving, and the person is no longer moderately to severely ill
• Vaccination may be given to asymptomatic or presymptomatic individuals with suspected or confirmed COVID-19 infection, or those who have fully recovered and are now asymptomatic, even if criteria to discontinue isolation has not been fulfilled, especially if another opportunity to be vaccinated is not likely 

Timing of Vaccination

During vaccination, it is essential to follow the local programs for control of priority diseases, if available.  

Timing of Seasonal Influenza Vaccination  

The influenza vaccine is administered yearly to provide optimal protection against influenza virus infection. Vaccine should be administered before influenza activity in the community begins and should commence throughout the flu season due to its varying duration.   

Vaccination campaigns may start earlier (July-August or as soon as vaccines are available) to ensure that there is sufficient time for the community to be vaccinated against influenza while adapting to the social distancing practices implemented in different countries to reduce the spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).    

Northern Hemisphere   

In the northern hemisphere, annual vaccinations are typically administered to high-risk individuals and their close contacts by the end of October. Vaccinations that are given in December or later might be considered in most influenza seasons. Influenza activity typically occurs from October to May.   

Southern Hemisphere   

In the southern hemisphere, annual vaccinations are typically administered to high-risk individuals and their close contacts between March to May. Influenza activity typically occurs from April to September.   

Tropical or Subtropical Regions   

In tropical or subtropical regions, laboratory-confirmed influenza can occur anytime throughout the year. The peaks of influenza activity can occur 1-2 times in a year. Epidemics often coincide with the rainy season. Public health programs where high-risk individuals and their close contacts are vaccinated should be performed at the same time each year if >1 peak of influenza activity occurs within a year. The latest available vaccine formulation should be used.   

Recommended Target Groups for Seasonal Influenza Vaccination 

Seasonal influenza vaccination is recommended for all persons ≥6 months of age without contraindications. During pandemics or outbreaks, when vaccine supply may be limited, high-risk groups and their close contacts may be prioritized. For individual protection, the administration of seasonal influenza vaccination is recommended for the following persons at higher risk for complications secondary to severe influenza:

• All persons aged ≥6 months without contraindications
• Children aged 6-59 months
• Adults aged ≥50 years old
• Immunocompromised individuals, including those with HIV, cancer, or undergoing treatment (eg chemotherapy, radiation therapy, chronic corticosteroids)
• Individuals with chronic pulmonary (including asthma, chronic obstructive pulmonary disease [COPD], cystic fibrosis), cardiovascular (congenital heart disease, congestive heart failure, coronary artery disease except for isolated hypertension), renal, hepatic, hematologic (eg sickle cell anemia), neurologic (eg stroke), and metabolic disorders (including diabetes mellitus [DM] and mitochondrial disorders)
• Individuals with body mass index BMI ≥40 kg/m²
• Children and adolescents 6 months to 18 years of age currently receiving Aspirin- or salicylate-containing medications who will be at increased risk for Reye's syndrome after a bout of flu 
• Women anticipating pregnancy, pregnant or at least 2 weeks postpartum during the flu season
  • WHO considers the vaccine safe at any gestational age of pregnancy
• Poultry workers, pig farmers, and those in the pig-slaughtering industry
• Close contacts of high-risk individuals (eg healthy household members, caregivers, healthcare workers)
• Residents of institutions for the physically and mentally disabled, nursing homes, and other long-term care facilities
• Members of other groups are advised to consult their physician should they wish to obtain seasonal influenza vaccine

Infection Control or Isolation Procedures

Infection Control Measures for Outpatients  

It is highly advised that outpatients frequently wash their hands with soap and water, cover their nose and mouth when sneezing or coughing, and dispose of nasal and mouth discharge and used tissue papers properly. It is recommended that ill persons use surgical masks since paper masks are not recommended. All members of the household should be educated on personal hygiene and infection control measures (eg hand washing, use of surgical mask) and be advised to avoid sharing utensils, towels, and beddings between patients and others. Advise them to clean all environmental surfaces soiled by body fluids with a household disinfectant according to the manufacturer’s instructions and make sure to wear gloves during this activity.   

For adults, there should be restrictions on social contacts (patients should not go to work, school, or other public areas). Advise them to continue infection control precautions until 21 days after the resolution of fever and improved or absent respiratory symptoms.   

For children under 12 years, there should likewise be restrictions on social contacts (patients should not go to school or other public areas). Advise them to continue infection control precautions until 21 days after the resolution of fever and improved or absent respiratory symptoms.   

Individuals with exposure to birds or livestock potentially infected with avian influenza virus should adhere to personal protective measures (eg use of gloves, gowns, N95 masks, eye protection, frequent handwashing). Household members or other close contacts of diagnosed avian influenza patients who develop fever or respiratory symptoms should immediately contact the local public health authority or WHO hotlines. 

Isolation Precautions for Hospitalized Patients  

Isolation precautions implemented for all hospitalized patients with confirmed or suspected influenza A should include standard, droplet, or airborne precautions.   

Standard precautions require scrupulous hand hygiene before and after patient contact along with appropriate use of gloves or gowns when needed. Droplet precautions require wearing a surgical mask if within 1 meter of the patient. Airborne precautions are controversial and are only warranted for selected patient care procedures. If available, place the patient in an airborne isolation room (ie monitored negative air pressure in relation to the surrounding areas with 6 to 12 air exchanges per hour). When entering the room, use a high-efficiency mask, if available, or a surgical mask.   

During isolation, restrictions should be followed. If a single room is not available, place patients separately in designated multibed rooms or wards. Beds should be placed 1 meter apart from other beds and preferably separated by a physical barrier (eg curtain or partition). Limit the number of healthcare workers who have direct contact with the patient. These healthcare workers should not look after other patients. Restrict the number of visitors and provide them with the appropriate personal protective equipment (mask, gown, gloves, face shield, or goggles) and instruct them in their use.   

Hospitalized patients discharged after less than 14 days should implement the necessary isolation precautions as mentioned above for outpatients.   

Clinicians should check with the local health authority for the latest updates because recommendations will change as new information becomes available.