the influenza Flashcards
what does a flu virus look like?
eight genes inside, spikes on outer surface
what are the parts of the virus and the human cell that binds together to trigger an immune response?
2 proteins on the virus’ surface- hemagglutinin (H) and neuraminidase (N)
recognized by antibodies in the immune system
what processes does the flu virus use to change form?
“antigenic drift”
H proteins come in 15 varieties; N proteins come in 9 varieties– not every combination works
what processes does the flu virus use to change form?
“reassortment”
mixing of genes from different flu strains; this can cause a shift in surface proteins, producing new strains of H and N numbers
what happens after a shift or reassortment?
the human immune system cannot fight it as they have no antibodies to the new strain
what part of the human anatomy does the flu virus most often attack?
the respiratory tract
what are the steps involved in producing a flu vaccine?
surveillance strain selection manufacturing and production purification and testing filling and packaging shipping vaccination
surveillance
what must be identified before production can begin each year?
influenza vaccine protects against three prominent virus strains (the three must be identified)
surveillance
what is key to predicting which three strains will circulate each influenza season?
ongoing global surveillance
strain selection
what do world health officials do?
analyze and identify the dominant circulating strains
strain selection
why are the strains submitted to the Food and Drug Administration (FDA)?
to recommend which three to include
strain selection
what does the FDA distribute?
seed viruses to manufacturers to begin the production process
strain selection
what do manufacturers’ scientists predict?
the circulating strains for the coming season and begin preparing vaccine at risk before final FDA selection
manufacturing and production
how are vaccines made?
each virus strain is produced separately and later combined to make one vaccine
manufacturing and production
how are chicken eggs used in this process?
millions of specially prepared chicken eggs are used to produce the vaccine. for seven months, fertilized eggs are delivered to the manufacturer. each egg is cleaned with a disinfectant spray and injected with one strain.
manufacturing and production
how do we collect the virus?
the eggs are incubated for several days to allow the virus to multiply. after incubation the virus loaded fluid is harvested
purification and testing
how do they ensure that the virus is inactive?
the virus fluid undergoes multiple purification steps and a special chemical treatment
purification and testing
how do they split the virus?
by chemically disrupting the whole virus
purification and testing
what viral fragments are combined?
viral fragments from all three strains are collected from different batches, and combined upon completion of quality control tests
purification and testing
why do manufacturers and the FDA test the vaccine concentrate?
to determine amount and yield of the virus to ensure concentrate is adequate for immunization
filling and packaging
when is the vaccine released for distribution?
upon FDA approval and licensing, in time for immunization
filling and packaging
after manufacturers begin filling the doses into vials and syringes, which are then sealed and carefully inspected, labels are applied. what do the labels show?
the vaccine batch, lot numbers, and expiration date
filling and packaging
what must happen before manufacturers can ship?
each lot must be specifically “released” by the FDA
shipping
when do vaccine shipments typically begin?
in August/September and continue into November
shipping
why are partial shipments sent early into the season to all customers?
to ensure broad access for high-risk patients
shipping
when would additional doses may be released and distributed into December and beyond to support late season immunization?
depending on viral yields and virus activity
vaccination
who is immunized?
particular high-risk populations
other persons who wish to reduce their risk for influenza
vaccination
when does immunization generally begin?
in October or as soon as vaccine becomes available and continues through the influenza season which typically ends in March
vaccination
when does immunity develop?
approximately two weeks following vaccinations
when does surveillance occur?
year round
when does strain selection occur?
January-March
when does manufacturing and production occur?
January-July
when does purification and testing occur?
June-October
when does filling and packaging occur?
July-December
when does shipping occur?
August-November, beyond as needed
when does vaccination occur?
October and beyond
what processes does the flu virus use to change form?
“jumping”
viruses that infect different species combine viral genes during replication process
