Universal screening for SARS‐CoV‐2 infection: a rapid review
Cochrane published a rapid review in September 2020 where the effectiveness of universal screening for SARS‐CoV‐2 infection compared with no screening and the accuracy of universal screening in people who have not presented to clinical care for symptoms of COVID‐19 were assessed.
The evidence current up to May 2020 found 22 studies; 17 assessed people (cohort studies) and five were computer‐generated models (modelling studies). Studies took place in USA, Europe, and Asia. Two modelling studies reported on the benefits and negative effects of screening. One suggested that asking about symptoms at airports may slightly slow, but not stop, the importation of infected people. Another model reported that weekly or biweekly screening of healthcare workers may reduce transmission to patients and other healthcare workers in emergency departments. No studies reported on negative effects of screening.
Seventeen cohort studies and three modelling studies reported on whether screening can correctly identify those with and without the virus. Studies varied widely in the baseline level of COVID‐19, settings, and methods. All cohort studies compared screening strategies to a ‘gold standard’ test called RT‐PCR.
There was insufficient evidence from two small studies on rapid laboratory tests and repeated symptom assessment to tell how accurate they were in identifying healthy and infected people. Three studies modelled entry and exit screening in airports. One study missed 70% of infected travellers. Another detected 90% of infections, but used an unrealistic scenario. The third used very unreliable methods so could not use evidence from that study.
The confidence in these findings is limited because most studies did not describe their screening methods clearly, some found very few cases of infections and the types of participants and settings varied greatly, making it difficult to judge whether the results apply broadly. One‐time screening in apparently healthy people is likely to miss people who are infected and are unsure whether combined screenings, repeated symptom assessment, or rapid laboratory tests are useful. As more people become infected, screening will identify more cases. However, because screening can miss people who are infected, public health measures such as face coverings, physical distancing, and quarantine for those who are apparently healthy, continue to be very important.
The review can be accessed at https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD013718/full#CD013718-abs-0002