Cowling 2010.
| Methods | Retrospective cohort study carried out to test whether entry screening practices delayed the onset of endogenous (i.e. not linked with travel of travel contacts) cases of nH1N1 during the recent influenza pandemic in countries which had introduced them compared to countries which had not | |
| Participants | 35 countries which reported more than 100 cases of nH1N1 influenza to WHO by 6 July 2009 and for which entry policies could be ascertained or date of first untraceable local case (n = 26 countries). Participants excluded Mexico and US where transmission seemingly occurred earlier | |
| Interventions | Dates and types of entry screening: temp check prior to disembarkation, health questionnaires from traveller with H1N1 cases, observation of arrivals for symptoms and thermal body imaging. There was wide variation in implementation with China and Japan implemented all 4, and 5 other nations none (Table 1) | |
| Outcomes | Laboratory: n/a Effectiveness: dates of first imported pandemic influenza case and confirmation of first untraceable case (identified by Google and sundry searches) Safety: n/a |
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| Notes | The authors conclude that entry screening provided an additional 1 to 2 weeks’ delay with distributions delay ranging from 0 to 30 days (the CIs of median days of delay overlap). The authors question the cost‐effectiveness of entry screening given the uncertainty of its effects and the enormous amounts of resources required to implement it This an interesting broad‐brush study, heavily dependent on web‐based searches but with a wide‐ranging scope reflected in the multilingual capabilities of the study group. Its many weaknesses are known to the authors and are discussed. |
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| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | N/A |
| Allocation concealment (selection bias) | Unclear risk | N/A |
| Blinding (performance bias and detection bias) All outcomes | Unclear risk | N/A |
| Incomplete outcome data (attrition bias) All outcomes | Unclear risk | N/A |
| Selective reporting (reporting bias) | Unclear risk | N/A |