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Flu Vaccine

by: Dr. Reagan Tan

The Disease
Influenza is caused by Haemophilus influezae. It occurs worldwide with humans the only known reservoir. It is recovered from the upper airway. Transmissions are through airborne droplets and direct contact with secretions. Risk factors of acquiring this disease include household crowding, large household size, low socioeconomic status, school-aged siblings, race sickle cell anemia, antibody deficiency syndromes, malignancies, and gender.

The Vaccine
It is a polysaccharide conjugate vaccine, stimulating T cell dependent immunity. It enhances antibody protection production especially in children. The vaccine is highly immunogenic with estimated clinical efficacy of 95-100%.

The Indications
• Routine immunization of Hib is indicated only for children less than 5 years of age
• Previously unvaccinated persons older than 59 months of age with one of the high risk conditions below should be given at least one pediatric dose of any Hib conjugate vaccine
• Individuals more than 50 years of age
• Healthcare workers
• Resident of chronic care facilities and nursing homes
• With chronic disorders:
  o Chronic pulmonary diseases (including bronchial asthma)
  o Chronic cardiovascular/renal/liver disease
  o Neurological disorders
  o Chronic metabolic disease

• Pregnant women in the 2nd or 3rd trimester without a flu shot in the last 12 months
• Healthy persons providing essential and emergency community services
• Student and other persons in institutional settings
• Functional or anatomic asplenia (sickle cell disease, post splenectomy)
• People living with HIV who acquire splenic dysfunction, whether or not they were immunized in infancy
• People living with HIV who have recovered from Hib disease and have risk factors for further disease, those with recurrent pulmonary infections or other risk factors for severe disease
• Immunodeficiency
• Immunosuppression from cancer therapy
• Receipt of hematopoietic stem cell transplant

Dose and Schedule
• Single dose of 0.5 ml intramuscular injection (or subcutaneous injection in persons with bleeding disorder), preferably in the deltoid, annually

Special Situations
  HIV-infected individuals and other persons with altered immune status
o Maybe given safely to people living with HIV regardless of CD4 T cell count considering the individual patient's risk of Hib disease and the effectiveness of the vaccine for these persons
o Patients with Hodgkin's disease should be vaccinated at least 2 weeks before the initiation of chemotherapy or, if this is not possible, 3 months after the end of chemotherapy

  Pregnancy and Breastfeeding
o Recommended for pregnant women at increased risk of Hib disease (eg. hyposplenia, asplenia)
o Available clinical data suggest that it is unlikely that use of Hib vaccine in pregnant women would have any deleterious effects on the pregnancy

  Transplant Recipients
o H. influenzae type B vaccination is also known to be safe and effective in bone marrow recipients and solid organ recipients
o Given 6-12 months post-HSCT

Side Effects and Adverse Effects Local
o Swelling, redness or pain at the injection site Systemic
o Fever, irritability
o Serious adverse effect are rare

Precautions and Contraindications
• Severe allergic and life threatening reaction to a vaccine component (eg. egg) or following a prior dose
• Moderate to severe acute illnesses with or without fever
• History of Guillain-Barre syndrome within 6 weeks following a previous dose of vaccine

Vaccine Storage and Handling
• Unreconstituted or liquid vaccine should be stored at 2-8oC
Locally Available Vaccines

Split Type Vaxigrip (Sanofi Pasteur) Fluarix (GSK) Single IM 0.5ml; Given Annually
Inactive Influenza Aggripal S1 (Novartis) Influvac (Solvay Pharma) Single IM 0.5ml; Given Annually
Split virion inactivated Intanza (Sanofi) 15 ug in a prefilled syringe, ID Indicated only for patients more than 60 years old

PSMID Guidelines on Immunization
Philippine Foundation for Vaccination

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