November 1 (Infectious Disease Epidemiology)

Question 1

What are study designs for infectious disease?

Answer 1

• observational studies and RCTs
• cohort study: inception cohort are people who are at a certain stage of illness (strengths are you can find incidence, temporality, you can measure risk factors you are interested in and other covariates. challenges are people can drop out, expensive.)
• case control study: starting with people who have the disease or don’t and looking if they had the risk (challenges are are your controls being selected from the source population)

Question 2

What are serosurveys?

Answer 2

• cross sectional study
• can be used as a counting exercise (use antibodies to see how many people are exposed) or estimate risk
• measure IV and DV at the same time
• relatively inexpensive, can be done rapidly, for virology it’s the method of choice for seroepidemiology
• lack of temporal association

Question 3

What are outbreak investigations?

Answer 3

• two components: descriptive and analytic component
• descriptive: define outbreak in terms of person, place, or time
• if there is a particular question, may do a cohort/case-control study (analytic component)

Question 4

How is vaccine efficacy measured?

Answer 4

• direct and indirect effects
• indirect effects: by you being vaccinated, does it indirectly protect others around you who weren’t vaccinated?
• OR is 0.2 for a vaccine then the protectiveness would be 80%

Question 5

What were the results of herd immunity study in rural colonies with randomly assigned hep A or influenza vaccines?

Answer 5

• people who did not get the vaccine but living with the kids who did get vaccines had a 60% protective effect
• 60% efficacy effect for getting the flu shot as well (for people living in general communities and in these communities)

Question 6

What is the test negative design for influenza?

Answer 6

• people come to the doctor with flu-like syndrome and get swabbed
• if you are positive for flu, you are a case and if you are negative, you are a control
• then look at how many were vaccinated for the flu
• potential biases (you have to be seeking healthcare)

Question 7

What is infectious disease modelling?

Answer 7

-involves building mathematical models usually based on assumptions to predict spread, risk, or efficacy of intervention