Test and trace ... and test again?

Editor – I read with interest the rapid report on contact tracing for SARS-CoV-2.¹ The authors refer to the potential for a much larger network of potentially secondarily infected contacts, but don't address how this could be solved other than by prompt contact tracing. One addition to the current system which may help would be testing of all identified contacts. This is standard practice in the given examples of sexually transmitted infections and tuberculosis, and recommended for SARS-CoV-2, yet remains curiously absent from the NHS Test and Trace programme unless contacts develop symptoms.^2,3

Testing of all contacts, regardless of symptoms, would ensure any secondarily infected contacts (including those who are asymptomatic or presymptomatic) are identified early, enabling their own contact tracing processes to be started promptly. It could also aid compliance to self-isolation for those with positive tests. This would need to be offset by clear messaging and incentives to reinforce the need for ongoing isolation in those with negative tests; one potential solution would be to offer tests at multiple timepoints during the isolation period, to ensure continued compliance and to confirm negativity prior to release from isolation.

The test, trace and isolate (TTI) modelling group published a report in November advising that daily test of contacts could offer an improvement over the current strategy; consideration should be given to implementing testing for all traced contacts at the earliest opportunity.⁴