Influenza and Vaccines Flashcards
Why is influenza significant?
Epidemics of it occur every year
It is ubiquitous and very common
It kills people (mainly elderly and children)
What are the key differences between influenza A and influenza B?
Influenza A: bird virus (RNA) with lots of strains, causes epidemics and pandemics, has 8 genes and 10 viral proteins (H/N nomenclature)
Influenza B: human virus (RNA) with only one strain, only causes epidemics
What was the first strain of bird influenza to enter human populations and how did its affects differ then to now?
H1N1 (1918) killed more people than WW1, mostly young people as old people had some immunity. It has remained causing seasonal epidemics since then but doesn’t kill people as we all have immunity now
How long does an influenza infection last and what are its symptoms?
High fever, muscle aches, lethargy, no appetite for 5-6 days (worst on 1st day then gets better)
Why is someone with cold symptoms more likely to have influenza in June than February?
There is no influenza circulating in February
Why do we continue to have influenza infections and epidemics each year despite gaining immunity upon catching it?
The RNA virus has no proof reading capacity so surface glycoproteins continuously mutate sufficiently enough to not match current antibodies (antigenic drift)
What is the name of the protein that connects the virus to sialic acid in the cells of your respiratory tract?
Haemaggluttinin
What does neuraminidase do?
Acts like scissors and snips the haemaggluttin off from the sialic acid so the virus can go off and infect more cells
What causes influenza symptoms?
Interferon alpha
What are the two ways that influenza can kill you?
Cytokines go crazy and cause multiple organ failure
Lungs get damaged so badly respiration cannot occur
How is influenza transmitted?
By droplets ( virus can live on a surface for up to 24 hours)
Which influenza drug is a neuraminidase inhibitor and what are the issues with it?
Oseltamivir- only really effective if given within 48 hours of infection so by the time the person comes to the doctor it is usually too late. But it does work very well with preventing at risk people getting sick
What is a seed virus used in a vaccine?
A non virulent laboratory strain containing the H and N from the predicted circulating strain
Which virus is actually used in the vaccine?
Trivalent vaccine containing the antigen from all three potential influenza strains, cultivated in a chicken embryo and split/washed so no active virus ends up in the vaccine
What is an alternative to vaccines that is difficult/expensive to produce?
Live attenuated vaccine
