Covid-19: More Test or Accurate Test, is the Question
Guest Author
Dr Kanav Kahol, CEO, Pink Tech Design
As the looming threat of coronavirus continues to spread with the increasing number of infections and casualties, quality testing has become imperative. The criticality revolving around Covid-19 test adequacy, test facility, test availability and accessibility and the overall test strategy need to be addressed and resolved on an urgent basis in a move to dissipate the cascading effects of the pandemic.
Currently, there are many inadequacies in the testing ecosystem - false negative test results, sample collection practices and test performance and reliability. According to the Centre for Global Development, since India began Covid-19 testing in February till June 1, 2020, it had conducted around 3.8 million tests. However, the testing capacity is still drastically insufficient according to the size of the population, for instance, daily tests per 1,000 people are only 0.08 in India while the number is 1.16 in the United States and 1.02 in Italy (as of May 30).
To enhance our ability to control the pandemic, it is significant to know who is infected, who has been in contact with infected people, and who is immune. This is possible only if our Covid-19 testing facility is adequate.
Challenges Facing Testing
Significant challenges exist about how tests are conducted and applied in practice and how the test results are interpreted. Let's explore some reported issues that might potentially hamper the quality of the test and solutions to it:
Equip Diagnostics with Proper Instruments and Testing Kits
Prompt collection and testing of samples from patients meeting the suspected definition for COVID-19 are crucial for proper monitoring and control of infection in the community.
Sample Collection Practices
Unintentional variations in the sample collection process, such as air swabs, can result in lack of sample, which, subsequently, can produce errors in test results.
Test Performance and Reliability
It is important to gather maximum data on test sensitivity and specificity as they form the basis for decision making for patients, providers, and policy makers.
Testing Facility in India
The pandemic has had a significant impact on clinical microbiology laboratories since its outbreak. Currently, two types of testing are available in India. One is the most dependable testing i.e. RT-PCR based testing which takes between 2-5 hours to conduct and another one is Antigen based testing which is recently approved by ICMR and takes less than 30 minutes.
RT-PCR based testing remains the molecular test of choice as it has high sensitivity and specificity. Even the WHO recommends using RT-PCR testing. However, the establishment of this test facility involves a huge cost and requirement of expertise, trained technicians, investment and time. Moreover, while RT-PCR test diagnoses the infection by detecting the presence of a live virus, the antibody test tracks the history of infection by detecting antibodies specific to COVID-19. The rapid antibody tests are a better choice for epidemiological studies and surveillance assessments. Therefore, alternative testing systems that can deliver swift reports and require limited resources will be highly useful. A combination of both these testing protocols would enable a comprehensive testing approach in India.
Significance of Test Positivity Rate
The Centre for Global Development's report reveals that as of June 1, over 100,000 tests are carried out in India every day and the test positivity rate stands at about 5 percent. Though TPR is within the WHO's recommended rate of <10 percent, it is adequate only for the current size of the outbreak. However, a very low value of the TPR might also be bad news as it might be an indicator that testing is completely missing even for those who are likely to be infected. We need an almost tenfold increase in the number of daily tests to keep the positivity rates low.
The positivity rate captures both the size of the pandemic and the scale of testing. A state might be executing a very large number of absolute numbers of tests but still have a very high positivity rate which means not enough testing is being performed. India needs to increase its testing capacity to 5, 00,000 cumulative Antigen and RT-PCR testing to control the spread of the pandemic and come close to 5% TPR as per WHO recommendations.
Further, the raw number of tests carried out daily must be analysed either in the context of the scale of the pandemic i.e. TPR or the population in a given area i.e. the number of tests per million. Now, tests per million is a good method but it does not take into consideration the fact that different populations experience different levels of infection. For example, at 10,075 tests per million (according to Statistica), Delhi has one of the highest rates but that is because of the low population in Delhi. Therefore, we need a better method to see if a state is doing well or not.
Summing It All Up
We all need to agree that a bad test is worse than no test, however, a good test is only effective and useful if carried out in a carefully designed strategy. Testing remains a mainstay of any pandemic response and the world is excited and hopeful about technological advancements and approaches developed by researchers and industry as it may expand testing capacity and increase diagnostic technology. Hence, there is no scope for complacency; testing needs to be improved big time.
