Why testing is paramount | The Daily Star
12:00 AM, April 02, 2020 / LAST MODIFIED: 01:25 AM, April 02, 2020

Why testing is paramount

The Covid-19 pandemic has touched almost every territory of the world and terrified its 8 billion population. As of this article going to print on Wednesday, some 876,782 people have been infected by the disease and the global death toll stands at 43,533 and counting. There are 648,284 active cases, many among them in critical conditions, while the number of patients who recovered are 184,965. Those who keep an eye on the day-to-day update of the outbreak can understand how quickly the virus is spreading. In many countries, the contagion has pushed their healthcare systems to the limit.

In this situation, the most important thing that a country can do is testing. Because, testing allows the infected people to know that they are infected. This can help them receive the care they need and let them take measures to reduce the probability of infecting others. Responsible agencies can take appropriate measures involving contact tracing, quarantine and isolation once the infected are identified. On the other hand, if an infected person goes unidentified, they risk infecting others. Even if they stay at home, they are likely to infect their family members and spread the infection in their neighbourhood. Therefore, testing is critical for an appropriate response to such a highly contagious disease. It allows us to understand the nature of the spread of the disease and take evidence-based steps to slow down the spread.

If we look at the infection figures of the Covid-19 globally, we can have some understanding as to why large numbers of testing are essential in a pandemic. The more tests a country has done, the more confirmed cases it has. Since we can only get a positive test if a test is carried out in the first place, countries that have performed more tests tend to have more confirmed cases. In other words, there is a positive correlation between tests performed and cases confirmed. That doesn't necessarily mean that countries that have done more tests really have more cases, although in many cases they might. However, the differences between countries can tell us important things. For instance, we can see that some countries have done more tests per confirmed case. For example, the UK has done more tests than other European countries with a similar number of confirmed cases. A look at a chart showing the number of tests performed in each country can also be quite revealing. For instance, South Korea has done more tests than other countries. Inevitably, it can be expected that the number of confirmed cases or positive test results in South Korea is closer to the real number of infected people than it is in other countries.

For a contagion like Covid-19, per capita tests performed in a country is also another crucial factor. Just look at a chart that takes the size of the population into account and shows the total number of tests per million people against the total number of confirmed cases (per million people). The higher the dot, the more tests per million people have been carried out in that country. The further right it is, the more tests per million people have come back positive. Therefore, we see that countries with higher rates of confirmed cases tend to be also countries where a larger share of the total population has been tested.

However, again, there are important differences between countries. Vietnam, for example, shows a much higher testing rate than Indonesia, although as of March 20, both have a similar number of confirmed cases per million people. From this perspective, it is clear that the US is lagging behind. The number of tests per million people in the US is almost 10 times lower than in Canada, and about 20 times lower than in South Korea. The US has been lagging behind these countries in terms of rolling out their testing strategy, although it seems to be fast catching up. Indeed, the number of a country's population and the capability of its health system are two main factors that determine how many tests a country can perform.  

Unfortunately, the capacity for Covid-19 testing is still low in many countries around the world. For this reason, we still do not have a good understanding of the spread of the pandemic. Bangladesh is not an exception and testing is still available only in Dhaka (although some measures to decentralise testing are underway). The number of tests carried out since the first Covid-19 patient was identified in Bangladesh has crossed 1,600 and, out of them, 54 positives have been identified so far. This number is not satisfactory. The tests should have been started earlier and by this time thousands of tests should have been done.

The reality is, we have never faced such a pandemic in the past and our capability to tackle this is not strong enough. But we got enough time to prepare for the outbreak since the disease originated in December 2019 in Wuhan, China. We had over two months' time to prepare several testing laboratories with trained personnel. The most common tests for Covid-19 involve taking a swab from a patient's nose and throat and checking them for the genetic footprint of the virus by a technique called RT-PCR. The method was developed soon after the onset of the outbreak and now it is part of the World Health Organization's recommended protocol for dealing with the disease. Definitely, we could have adapted it and started it across the country. Diagnosing the disease by this technique is not very easy and it needs trained personnel under the supervision of experts. It also needs proper containment of the diagnostic facility, called a Biosafety Level 2 (BSL2) laboratory, in order to protect the working personnel and also to contain the disease from spreading from the laboratory.

In two months' time, we could upgrade our existing laboratories to BSL2 and develop some new ones utilising our resources. However, it is heartening to know the ministry of health has taken the initiative to set up diagnostic facilities at the division and district levels. Some selected medical colleges will have the capability to test soon. Local experts from different institutes and universities should be coordinated and mobilised to quickly launch those facilities and keep them under safe operation. Test quality control is also very important. Generally, in RT-PCR, quality control is a challenging task and the quality of test results can be compromised in any step down the process like sample collection, viral RNA extraction, PCR mix preparation, running the PCR reaction, etc. Any possible contamination while handling RNA has to be strictly avoided and appropriate controls have to be put in place in every step. The process requires strict temperature control and an absolutely contamination-free environment, otherwise the specimens can show false negative/positive results.

These are the reasons why the tests should be performed under a uniform guideline or protocol that should be developed considering our context without any further delay. So far, the number of positive cases identified per tests performed in Bangladesh is quite different from that of other countries. It is imperative that we take extra measures to maintain the quality of our tests.  

The government has taken some serious measures to contain the disease so far. People have also responded well and they seem to be quite aware of the danger. However, we have to keep in mind that a huge number of people entered Bangladesh from countries worst affected by the Covid-19 pandemic in February and March. An outbreak may start from any corner of the country at any moment. Therefore, the next few weeks are very important for us in tackling the spread of the disease. We know the limitations of our health system and hospitals, public or private. The system will be saturated early in a potential Covid-19 outbreak which causes patients to require critical care. It will also be a challenge to keep our healthcare professionals safe across the country. As well as addressing these challenges, our strategy should be centred on doing more and more tests of the suspected patients as well as subsequent isolation or quarantine of their contacts to prevent further transmission of the virus. Indeed, it is a tough time for all of us. Nevertheless, by undertaking pragmatic steps we can overcome the current crisis and prepare for the future challenges.

 

Muhammad Sougatul Islam, PhD, is a public health researcher and Director at BioTED.

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