Influenza Vaccine: What to select? Trivalent form or Tetravalent Form
Vaccination is the process of immunizing an individual from life threatening diseases and infections. The principle of vaccination is to administer an antigen either in a heat killed or live attenuated form, to elicit a potent secondary antibody response in future. The secondary antibodies that are formed neutralize the effects of disease or infection causing antigens (with which an individual is already immunized) in the long run. One such vaccine that is popular in use is the influenza vaccine. The Influenza vaccine which is commonly referred to as “Flu-Shot” is an annual vaccination that provides protection against various strains of influenza virus. The vaccine is available in two classes- the trivalent flu vaccine and the tetravalent flu vaccine.
Both these classes are so named according to the strains of influenza virus, against which it offers protection. The trivalent form offers protections against three strains of influenza virus- influenza A virus (H3N2), influenza A virus (H1N1) and one strain of influenza B virus. On the other hand the tetravalent form offers protection to an additional strain of influenza B virus, in addition to the strains covered by the trivalent form. The trivalent form is an inactivated or heat killed type of antigen while the tetravalent form is used as live attenuated form. Apart from its coverage, the vaccines also differ in their potency and adverse effects profile. A comparison of both these forms of influenza vaccine is provided as below:
| Features | Trivalent Influenza Vaccine | Tetravalent influenza Vaccine |
| Coverage of influenza viruses | Offers protections against three strains of influenza virus- influenza A virus (H3N2), influenza A virus (H1N1) and one strain of influenza B virus | Offers protections against four strains of influenza virus- influenza A virus (H3N2), influenza A virus (H1N1) and two strains of influenza B virus |
| Form in which used | inactivated or heat killed | live attenuated |
| Magnitude Of Secondary Antibody Response | Lower than the tetravalent form | Higher than with trivalent form |
| Potency of administered vaccine | Lower, as because probability of coverage of all B strains are not possible | Higher, as because probability of coverage of B strains are higher |
| Presence of live influenza virus in vaccine | No | Yes |
| Time of administration | Prior to flu seasons hence are the typical flu vaccines | Anytime during the year |
| Target Population | 6 months and older | 2 years and older |
| Efficacy in Child and elderly | In child efficacy documentedIn elderly efficacy is classified as “acceptable” | In child efficacy documentedIn elderly efficacy is classified as “medium” |
| Manufactured from | Fertilized chicken eggs | |
| Safety | Safe , may cause reactions like pain, redness and swelling at injection site | Since live vaccine it is less safe than trivalent form |
| Chances of Influenza | no chance of acute influenza | Chances of acute influenza is high as viruses are administered in live form |
| Systemic Adverse Reactions | Mild & Self limiting, with common symptoms like malaise, fever and myalgiaImmediate hypersensitivity ranges from urticaria to angioedemaFebrile seizures may occur
Guillain-Barre syndrome might be present Headaches, cough chills and sinusitis common Rhinitis and nasal congestion uncommon |
More reports of fever Immediate hypersensitivity ranges from urticaria to angioedemaFebrile seizures may occurGuillain-Barre syndrome is not correlatedHeadaches, cough chills and sinusitis common Rhinitis and nasal congestion common |
| Population most susceptible to adverse reactions | Young children having no previous exposure to influenza vaccine | All individuals having no previous exposure to influenza vaccine |
| Contraindications | Prior incidence of allergy to seasonal influenza vaccines(trivalent form)Should not be administered strictly to infant under age of 6 monthsSafe in pregnancy Egg allergy Safe in asthma |
Prior incidence of allergy to seasonal influenza vaccines(tetravalent form)Should not be administered strictly to children under age of 2 years or adults over the age of 50 yearsPregnant woman and patients receiving aspirin or salicyclates
Egg allergy Metabolic diseases and asthma |
| Dosage route | Intramuscular | intranasal |