Influenza%20(pediatric) Management

• Vaccines are the primary preventive measure against influenza
• Vaccine used should comply with current World Health Organization (WHO) recommendations
  • Annual seasonal influenza vaccination is recommended for all pediatric patients ≥6 months of age
  • Highly recommended for pediatric patients at increased risk for complications

Influenza Vaccine

• Both inactivated and live attenuated influenza vaccine can be used for the prevention of pediatric influenza
• Quadrivalent vaccines are recommended for all pediatric influenza vaccines 
• Live attenuated virus vaccine 4 (LAIV4) is an option for patients in whom it is appropriate (≥2 years old, no risk factors for complications, no history of antiviral medication intake within 48 hours or up to 2 weeks if with previous Baloxavir use)
• Dosing depends on child's age during 1st dose and immunization history
  • Children 6-35 months old may receive either 0.25 mL or 0.5 mL dose
  • Children ≥36 months of age may continue to receive 0.5 mL dose
  • For children 6 months - 8 years old:
    • 2 doses ideally by end of October, separated by at least 4 weeks, are needed if given for the 1st time or <2 doses received before July 1, 2019
    • 1 dose needed by end of October if already received ≥2 total doses before July 1, 2019
  • Children ≥9 years old require only 1 dose

Composition:

• WHO has a global influenza surveillance program
  • The collaborating centers provide early warning system for emerging strains of influenza that have epidemic potential
  • This system is necessary to create effective vaccines that contain the current circulating strains

• Valency and composition depends upon the number and type of strains covered by the vaccine:
  • Trivalent vaccines: Contain 2 type A strains and 1 type B strain of influenza
  • Quadrivalent vaccines: Contain 2 type A strains and 2 type B strains of influenza
  • Recommended vaccine composition is issued yearly by WHO in March for vaccines used in the northern hemisphere and in October for vaccines in the southern hemisphere

• For the 2020/2021 northern hemisphere flu season, the recommended egg-based trivalent vaccine should contain an A/Guangdong-Maonan/SWL1536/2019 (H1N1)pdm09-like virus, an A/Hong Kong/2671/2019 (H3N2)-like virus and a B/Washington/02/2019 (B/Victoria lineage)-like virus
  • Quadrivalent vaccines will contain above 3 viruses, plus a B/Phuket/3073/2013–like virus (B/Yamagata lineage)
• For the 2020/2021 northern hemisphere flu season, the recommended cell- or recombinant-based trivalent vaccine should contain an A/Hawaii/70/2019 (H1N1)pdm09-like virus, an A/Hong Kong/45/2019 (H3N2)-like virus, and a B/Washington/02/2019 (B/Victoria lineage)-like virus
  • Quadrivalent vaccines will contain above 3 viruses, plus a B/Phuket/3073/2013–like virus (B/Yamagata lineage) 
• For the 2020 southern hemisphere flu season, the recommended trivalent vaccine should contain an A/Brisbane/02/2018 (H1N1)pdm09-like virus, an A/South Australia/34/2019 (H3N2)-like virus, and a B/Washington/02/2019-like (B/Victoria lineage) virus
  • Quadrivalent vaccines will contain above 3 antigens, plus a B/Phuket/3073/2013–like virus (B/Yamagata/16/88 lineage)

Inactivated Influenza Vaccine [Intramuscular (IM) or Deep Subcutaneous (SC)]

• Uses vaccine composition issued by WHO in March (northern hemisphere) and in October (southern hemisphere)
• Various types of inactivated influenza vaccine have been formulated to increase immunogenicity: Split-virion,whole-virion, surface-antigen/adjuvant containing vaccines (eg aluminum, monophosphoryl lipid, virosome)
• If the vaccine used contains the predominant circulating influenza strains, the vaccine can be 70-90% effective in preventing illness in healthy adults
• Patients with concurrent medical conditions may have a reduced rate of severe respiratory illness and death (up to 50%)
  • 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
• For individuals with history of egg allergy, the American Academy of Pediatrics (AAP) and Advisory Committee on Immunization Practices (ACIP) recommend to proceed with administration of influenza vaccine, although ACIP recommends specific situations based on previous symptoms:
  • Presence of hives/urticaria only should not be a contraindication
  • Those who experienced symptoms other than hives (eg angioedema, respiratory distress, lightheadedness, recurrent emesis) and needed Epinephrine or other medical interventions may receive influenza vaccine
  • Severe allergic reaction is a contraindication for vaccination with any form of influenza virus
  • A 15-minute observation period is recommended following administration of any vaccine
  • Patients/guardians who refuse egg-based vaccines may receive recombinant or cell-cultured products

Live, Attenuated Influenza Vaccine (Intranasal)

• Approved in some countries for the following uses:
  • Option for vaccination of healthy persons aged 2-49 years old
  • May be used in healthy individuals aged 2-49 years in close contact with high-risk groups except those in close contact with immunocompromised patients, or children aged 2-4 years diagnosed with asthma or with wheezing episode within the past 12 months