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Recruit athletes upon arrival at athletes village. Recruitment involves baseline survey and blood test. Follow up weekly during time spent in athletes village (depending on latency period) then 6 monthly post leaving olympics.

Challenges include obtaining consent - athletes focusing on training less likely to want to spend time filling out forms, undergoing blood tests.

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Challenges: exposures before they arrive at Brazil,different countries may have different prevention methods

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·      Loss in follow up with participants as they could be traveling elsewhere- home country, thus manipulating the incidence of person days

·      Participants would drop-outs of the study sample

·      Underestimation or overestimation risk estimate of cases within the target population, in the context that some participants could have similar symptoms, but could have a fever and not Zika. This leaves the question

1.     How do we diagnose that the target sample has Zika and not common fever.

2.     Do we conclude them sick based on common fever symptoms or through blood test

We would run blood test and rule out common fever

3.     How do we follow them up and how often to determine that it is indeed Zika and not a common fever

We would follow up target sample for a period of 4months, through phone calls. And this could also reduce the drop-out rate

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Follow time: through out the Olympic Games, person-day Need to pay attention to the athletes leave earlier;

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- loss to follow up of athletes after Olympic games finish

- loss to follow up of athletes who are disqualified/do not make it to the finals

- based on onset and duration of infection and symptoms, can use person days for new incidence

- exposure to mosquitoes: indoor sports versus outdoor sports

- Assessing symptoms versus laboratory confirmation of virus

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Prospective cohort study
athletes followed for weeks. Person time measured as person days.

Methodological challenges
time restraints - may not detect any disease cases

also may be difficult to recruit enough participants to have any disease cases

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FOLLOW UP TIME: 1 month (including follow-up in and after the Olympic Games)

Recruitment: all athletes

Assess incidence: analyse every athlete's urine sample or blood sample that taken before and after each game

methodological challenges:
communication barrier; collaboration with the health department of other countries after.

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measure the new incidence of zika virus among the athletes that competing in the 2016 olympic games and all women athletes that in reproductive age who competing in the 2016 olympic games will be the population at risk. the population at risk should be healthy proved by existing medical record (as athlete the record should be available). first, recruite all population at risk and ask for participating to fill participation form. follow up the participant for 3 weeks. assessment of new infection could be assess by medical doctor if the case come to seek health services during competition and at home country back.

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sor

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Recruit all the participanting athletes

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Exclusion criteria
=>Exclude people from countries

Follow up time
Given the incubation period of two weeks,

=> start observation two weeks after the athletes arrive

=> finish observation two weeks after the athletes leave

Methodological challenges

=> Language barriers
=> Test kit vs Lab test
(In terms of financial issue & accessibility, it is better to use test kits, but the results of test kits may not be consistent with that of lab test.)

Incidence rate
=number of cases/person-days at risk

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Prospective Cohort study

Recruitment: all participating athletes

Incidence rate: development of Zika symptoms from start of Olympic game (e.g. having Zika fever, giving birth to microcephaly infant)/person time for 1 year (2016-2017)

methodological challenges:
competing diseases that athletes could contract during their stay
symptoms may closely resemble that of Dengue fever, therefore, could be mistaken
Possibility of re-contracting the disease

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Follow-up

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recruitment: athletes participate in 2016 Olympic Games
follow-up time: person-days
start at 12 days after the athletes arrive and finish at 12 days after athletes leave

challenges: lost follow-up

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Methodological challenge: Loss to follow up

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Methodological challenge: Loss to follow up

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Recruitment: athletes who participant in 2016 Olympic games
Follow-up time: from the 13 days after they arrive the host country to they leave host country 13 days.

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Recruitment: athletes
Follow up time: 2 weeks (person-day)
study design: interviews/survey daily

Methodological challenges
- language barriers between interviewers and participants (when study is done during the Olympics)
- athletes leave early from Olympics?
- consent
- potential resource deficiencies?
- blood test every day! especially when undertaking official sports lab test?(incentive is they know if zika positive/negative results)
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If you were to design a prospective cohort study to assess the following question, what would be the optimal design (recruitment, follow-up time etc.) and what would be the methodological challenges?

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If you were to design a prospective cohort study to assess the following question, what would be the optimal design (recruitment, follow-up time etc.) and what would be the methodological challenges?

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The incidence of Zika virus infections among athletes competing in the 2016 Olympic Games