antibody
antigen
avian flu virus
blood
bronchitis
coughing
defense
disease
epidemic
epitope
fever
flu
flu virus
headache
hemaglutinin
human immune system
humoral immune response
illness
immune system
immunity
immunization
immunoglobulin
infection
infectous
influenza
macrophage
neuraminidase
opsonization
outbreak
pathogenic agent
pneumonia
protein
rna
russian influenza
spanish flu
specific
swine flu
vaccination
vaccine
viral infection
virus
weakness