Prevention of Seasonal Influenza Disease

FLUENZ is a prophylactic vaccine used for active immunization to prevent seasonal influenza disease. It is indicated for use in children and adolescents aged 2 years to less than 18 years. The primary therapeutic benefit is the reduction in the incidence of confirmed influenza cases and the prevention of subsequent clinical manifestations. The vaccine is utilized in annual vaccination programs to target specific viral strains circulating during the influenza season.

Managing Risk of Acute Flu Symptom Clusters

The preventative benefit is relevant for managing the symptoms that interfere with daily functioning, specifically the acute systemic and respiratory symptom complex characteristic of the flu. This includes managing the risk of experiencing clusters of symptoms related to physical discomfort, such as high fever and generalized body aches, as well as respiratory issues like cough and nasal congestion. By reducing the risk of contracting the disease, the vaccine assists in maintaining physiological and functional stability during the flu season.

Managing Risk of Severe Clinical Outcomes

The use of this vaccine is relevant for managing the risk of developing severe influenza illness and experiencing serious secondary complications, such as pneumonia. It is particularly focused on contexts involving heightened systemic burden, aiming to support pediatric patients by easing potential distress and reducing the risk of serious secondary health outcomes during influenza outbreaks.

Quick Fact Block

Regulatory References

1. European Medicines Agency (EMA) therapeutic overview

Eligibility for FLUENZ

FLUENZ is an attenuated live virus vaccine with strict, regulatory-defined eligibility rules. The officially approved age range is limited to children and adolescents aged 2 years through 17 years. Use is contraindicated in children younger than 2 years due to documented safety concerns regarding increased rates of hospitalization and wheezing in that specific population.

Absolute contraindications prohibit use in individuals with a history of severe allergic reaction to any vaccine component, including egg proteins or gentamicin. It is also strictly forbidden for those with clinical immunodeficiency or those receiving immunosuppressive therapy (e.g., high-dose corticosteroids). Furthermore, the vaccine is contraindicated for children and adolescents under 18 years of age who are receiving aspirin or salicylate-containing therapy due to the potential risk of Reye's syndrome.

Usage is not recommended during pregnancy or breastfeeding. Administration should also be postponed for individuals with severe acute febrile illness or those experiencing heavy nasal blockage. Individuals with severe asthma or current wheezing are also generally advised against using this specific vaccine formulation, as efficacy has not been fully established in these groups.

FLUENZ is an attenuated live virus vaccine, and its administration requires consideration of potential interactions with other medicines, particularly those affecting the immune system or containing salicylates.

Salicylates and Aspirin

FLUENZ must not be administered to children and adolescents under 18 years of age who are currently receiving salicylate therapy (e.g., aspirin). The use of salicylates during or shortly after vaccination may pose a theoretical risk of Reye's syndrome, an extremely rare but serious condition affecting the brain and liver, due to the association between this syndrome and wild-type influenza infection.

It is generally recommended that salicylates not be used for four weeks following FLUENZ vaccination unless specifically indicated by a healthcare professional.

Antiviral Agents

Concurrent use with influenza-specific antiviral medicines (such as oseltamivir or zanamivir) has the potential to reduce the effectiveness of the vaccine. It is recommended that FLUENZ not be administered until at least 48 hours after the cessation of antiviral therapy. If antiviral agents are administered within two weeks of vaccination, revaccination may be necessary, and clinical judgment should be exercised.

Other Vaccines

FLUENZ can generally be given at the same time as other live attenuated vaccines, including those for measles, mumps, rubella, and varicella, as well as orally-administered poliovirus. While the co-administration of FLUENZ with inactivated vaccines has not been specifically studied, healthcare providers will determine if concurrent administration with any other vaccine is appropriate.

Local Activation and Nasopharyngeal Targeting

The mechanism begins with the live attenuated virus strains undergoing attenuated replication within the nasopharyngeal epithelial cells of the upper airways. This process is restricted to this cooler area by the virus's cold-adapted, temperature-sensitive design. This limited, local replication serves as a generator of viral antigens, which are then recognized by the host's immune system, initiating the immune signaling cascade.

Dual Induction of Mucosal and Systemic Immunity

Following local antigen release, the host’s entire adaptive immune pathway is engaged. The vaccine induces the differentiation of B lymphocytes to produce Secretory IgA (sIgA), establishing a foundation for local immune response on the mucosal surface, while simultaneously activating T cells and generating systemic IgG antibodies. This process establishes immunological memory against the specific viral strains. The inclusion of multiple strains allows for the simultaneous induction of memory against all circulating antigens in the formulation.

Mechanistic Constraints

The entire mechanism depends on the initial viral replication phase; any external factor, such as antiviral agents or immunosuppressive conditions, that blocks this replication or suppresses the host's immune response will functionally antagonize the establishment of immunological memory.

The following instructions detail the administration of FLUENZ (Live Attenuated Influenza Vaccine, nasal spray) for individuals 24 months to less than 18 years of age.

Administration Scope

Procedural Requirements

Dose Division: The total 0.2 mL dose is delivered as 0.1 mL into each nostril using the single-use nasal applicator.

Technique: The recipient must be in an upright position. The patient can breathe normally during administration; there is no need to actively inhale or sniff the vaccine.

Procedural Constraints: Administration should be postponed in individuals with nasal blockage or those suffering from a severe acute febrile illness. Furthermore, administration must be delayed until at least 48 hours after the cessation of influenza antiviral therapy, due to the potential for reduced vaccine effectiveness.

Research Evidence / Overview of Studies for FLUENZ

Evidence for Prevention of Seasonal Influenza Disease

The main body of research for this condition has been evaluated in studies that examined how frequently laboratory-confirmed influenza illness occurs. Research included Randomized Controlled Trials (RCTs) that used either an inactive placebo or the injectable inactivated influenza vaccine (IIV) as comparators. These trials were evaluated in the core licensed population of children and adolescents aged 2 years to less than 18 years.

Studies observed the incidence of confirmed influenza cases across the study groups during single influenza seasons. This seasonal difference was associated with the similarity between the vaccine strains and the strains that were circulating in the community that year. Long-term effects are not fully established regarding the observed effect after revaccination over multiple, consecutive seasons. Also, findings were mixed regarding observed patterns against specific subtypes of the virus, such as A(H1N1), across different study settings and years.

Research Examining Severe Clinical Outcomes

Beyond confirmed infection, studies explored clinical outcomes considered more severe. Research examined the incidence of hospitalization (both influenza-related and all-cause) and lower respiratory tract illness (LRTI) events as studied in trials. This evidence was observed in observational cohort studies and through the analysis of secondary data points collected in the larger RCTs. These studies often focus on children with conditions characterized by fluctuating or episodic manifestations who may be at higher risk for severe illness.

Much of the data regarding severe outcomes comes from observational studies, which may be subject to limitations like confounding factors. Data for certain groups remain insufficient, particularly for children who have severe, uncontrolled underlying medical conditions included in clinical trials. Evidence quality varies across studies, and comparative evidence is lacking for some outcomes when comparing FLUENZ directly to all other available preventative options.

Common questions about FLUENZ (FAQ)

Q: Does FLUENZ contain live or inactivated (killed) virus?

A: FLUENZ is classified as a live attenuated (weakened) vaccine. According to the official product information, it contains influenza viruses that are active but have been modified so they cannot cause the flu. The regulatory documents note that these vaccine viruses are cold-adapted and temperature-sensitive, meaning they grow primarily in the cooler environment of the nose.

Q: What is the primary way FLUENZ is administered?

A: Regulatory documents state that FLUENZ is administered via the intranasal route, which means it's sprayed into the nose. This delivery method is designed to activate the immune system at the site where influenza typically enters the body. Regulatory documents clarify that the vaccine is administered intranasally rather than by injection, and it is supplied in a specific nasal device.

Q: Can FLUENZ be used for people who are immunosuppressed?

A: Official product information indicates that FLUENZ is not recommended for individuals who are severely immunosuppressed due to disease or medical treatment. This exclusion is a precaution required because the product is a live vaccine. However, specific regulatory documents allow its use in children with stable HIV infection who meet certain specified criteria.

Q: How long after getting FLUENZ does it take for immunity to develop?

A: According to official documentation, the immune response that provides protection against the influenza viruses usually develops within 10 to 14 days after receiving the vaccine. This timeframe is necessary for the body to build up enough antibodies. Regulatory data suggests that the full protective effect is typically established after this period.

Q: Is FLUENZ approved for use in infants under 2 years old?

A: Regulatory documents state that FLUENZ is not approved for use in children under 2 years of age. Official documents note that the safety and effectiveness have not been established in children under 2 years old, which is why it is not approved for this group. It is specifically licensed for use only in individuals within a higher, defined age range.

Q: Can FLUENZ be given to children who have asthma or recurrent wheezing?

A: Official information indicates that FLUENZ is contraindicated (should not be used) in children under 5 years of age who have recurrent wheezing or current asthma. This is noted due to risks observed in clinical trials within this specific group. For children aged 5 years and older, the vaccine can be considered, though consultation with a healthcare provider is necessary to determine appropriateness for those with chronic respiratory conditions.

The official requirements for storing and disposing of FLUENZ nasal spray suspension are defined by regulatory agencies to maintain the viability of the live attenuated vaccine.

Required Storage and Handling

Disposal Instructions

Any unused or expired FLUENZ must be discarded at the end of the flu season or immediately if the temporary temperature excursion limit is exceeded. The product must not be thrown away with household waste or disposed of in wastewater, but must be managed in accordance with local requirements for pharmaceutical waste.