A need to reassess the traveller testing strategy

The Government of Karnataka has advised travellers coming into the state to be tested for COVID-19 upon arrival. Private labs are being pressed into action to supplement the existing COVID-19 testing capacity. The advisory recommends collecting samples from incoming travellers, followed by an institutional or home quarantine period depending on the point of departure. The test costs INR 650 per individual and results are expected within 24 hours. While testing and isolating positive cases remains the most effective way to contain the spread of COVID-19, the current strategy does not account for the disease being picked up in transit.
Consider any traveller coming into Karnataka, either by flight or train. Even if they followed all social distancing norms and came from a low-risk area, they risk exposure to virus during their travel. Interaction with new people and physical interaction/proximity to them can increase risk of exposure to the virus. Further, since there is no control over who the fellow travellers are, there is possibility a person from high-risk area may be proximal to a person from a low-risk area. Hence, the segregation of people based on their original departure point is not an effective measure.
There are two scenarios – a traveller coming into Karnataka already has the disease (before travel) or contracts it during the travel. Under the current policy, if the traveller travels when infected, the test at the airport/station may detect the disease, enabling rapid monitoring of others who may have come in contact with her. This rapid response would be key to containing the disease.
But suppose the traveller has contracted the disease only a day prior to travel or during the travel. Their test will likely come negative – and a negative result will lead to a complacent approach to maintaining quarantine. Since 80% of COVID-19 cases in India are supposed to be asymptomatic, such a traveller may not even display symptoms and would be free to go out in the public after 14 days of quarantine.
Inadequate screening and quarantining in the early stages of COVID-19 outbreak have contributed to the spread of the disease in India. Hence, a stricter testing protocol is needed to mitigate the resurgence or spread of cases into new areas.
A comprehensive COVID-19 containment programme would include testing travellers on their arrival, quarantine for 14 days and a second test within 8-10 days of travel. The first test can help initiate immediate medical intervention for positive cases and medical monitoring of their contacts. This is a decisive step in preventing spread of the disease.
Since, there is a possibility of the travellers contracting the disease a day or so prior to travel or even during travel, it is crucial to follow the 14 day quarantine period, irrespective of the status of the test. Home quarantine, where feasible should be encouraged to reduce the burden on institutional quarantine capacity. Further, keeping high risk individuals in an institutional quarantine with other individuals can increase risk of disease spread.
Finally the third step would be to perform a COVID test anytime between day 7- day 10 of quarantine. If someone has contracted the disease, they will be likely to give a positive result in this time frame. This will reduce the likelihood of incoming asymptomatic travellers from spreading the disease post-quarantine.
However, this test-quarantine-test regime depends on aggressive testing and tracing of each individual who has entered the state. Excellent institutional quarantine facilities or monitoring of home quarantine capacities are also required to ensure travellers adhere to quarantine protocols.
Testing facilities need to be ramped up to achieve a quick turnaround on samples. Further the Government of Karnataka advisory suggests using pooled testing on incoming travellers, even for those coming from high-risk areas. This suggestion is against the recommendations of the ICMR advisory which suggests that pooled testing should only be used in areas of low disease prevalence. Pooled testing is not a cheaper substitute for RT-PCR. When pooled samples are all negative, 5 individuals can be tested using 1 RT-PCR assay. However, if there is one positive sample in the pool, all 5 samples need to be individually tested. In this case, pooled testing actually uses more resources than normal RT-PCR.
We might soon be in an era where upon arrival instead of taxi drivers heckling for rides, we will have private company representatives heckling people to get their COVID-19 tests done. There is a need for transparent regulation on how tests will be paid for, who can perform the tests, how samples should be pooled, and redressal mechanisms in case of any dispute. Testing is important and competition in testing will help increase coverage and reduce costs, but in the absence of standards and accountability, inappropriate testing measures can lead to chaos.
An effective containment protocol will come at additional cost – more testing, quarantine policing, logistics. But on the other hand, lockdowns on travel has already incurred a significant human and economic cost. The burden of containing COVID-19 falls on the government and society – if travellers follow quarantine rules, it will lead to lessening the strain on government expenses. Essentially the fight against COVID-19 depends on scientifically-driven policy and public trust – containing COVID-19 is something we all need to contribute to.