Influenza vaccine (inactivated)

How it works

It contains inactivated influenza virus antigens, reformulated each season to match anticipated circulating strains, which stimulate strain-specific protective antibodies.

Prescribing in practice

• Annual revaccination is required because circulating strains and antibody levels change, and the inactivated vaccine cannot cause influenza infection.
• Defer in significant acute febrile illness, and review egg-allergy status as some inactivated products are egg-grown, choosing an appropriate product per current guidance.
• Administer intramuscularly into the deltoid in adults, separating from other injections as advised.

Monitoring

No laboratory monitoring is needed; the patient should be observed briefly for immediate hypersensitivity after vaccination.

Counselling the patient

• You need a flu vaccine every year to stay protected as the virus changes.
• The injected vaccine is inactivated and cannot give you flu; a sore arm or mild fever can occur.
• Tell the vaccinator about any serious egg allergy or previous vaccine reaction.

Evidence & guidelines

Annual inactivated influenza vaccination follows the eligible groups and product recommendations of the UK immunisation guidance (Green Book) and seasonal flu programme.