It is also preferably known as “cluster containment strategy or analysis”. Cluster Testing is widely being used across the globe to curb the spread of Covid-19.
Introduction
Cluster testing is a strategy which helps in the collection of various cases of diseases within and limited to a defined geographical area by the early discovery of cases. It is also preferably known as “cluster containment strategy or analysis”. It helps in breaking up the chain of communication and lead to stoppage of transmission. In this way, it helps in preventing the widespread disease and infection in various new places and locations. Currently, Cluster Testing is widely being used across the globe to curb the spread of Covid-19 which has brought devastating impact on the entire world affecting the nation, various countries, industries, sectors, and the general public of the entire world. The Government of India and the State Governments decided that India would be following this strategy[1] for all cases like travel-related cases which are reported in India, or the locally transmitted coronavirus etc.
Cluster testing helps in breaking the connection and categorizing all the cases into cluster or group and study them individually to know their unique characters. Under the cluster testing which basically includes geographical quarantining, it also includes social distancing measures with enhanced and extra active surveillance, public to get testified in all suspected cases, if found positive, sending them to an isolation room. There is a huge responsibility on the authorities to conduct extensive contact and trace down all the active cases in all nook and corners of the country witnessing containment with the full lockdown.
History & Origin
Cluster analysis (Cluster testing) is a basic name which is used for a large number of statistical methods which helps in the detection of groups forming a sample of objects, which are called clusters[2]. Clustering is one of the elementary processes in data analysis, and the cluster arrangement of a data-set often has a noticeable effect on observed designs in data. Testing whether a data mining outcome is implied by the cluster arrangement can give considerable information on the formation of the data-set[3].
Pros & Cons
Cluster testing is a concept which has its own pros and cons. Later in this article, we will be discussing them in detail; there are various nations where this cluster testing has made the situation a lot better, but at the same time there are nations where it has failed miserably. Cluster testing is a conventional method for stopping everything and declaring lockdown at all places. This method can be helpful in breaking the chain of transmission. Cluster testing can be an important tool in the war against coronavirus. If the people follow it wisely and passionately, by not going out, taking reasonable precautions, the situation can get better like Bhilwara, Rajasthan or Indore in India and Singapore, Taiwan and Hong Kong. In cluster testing, huge measures are required to be taken while screening, taking reports from various individuals etc. Cluster testing requires a lot of care on both the public side and the authorities’ side as well. Talking about the cons, as cluster testing requires a large number of testing kits, it is difficult for India right now to make it available for its entire population. Firstly, it cannot be made available. Secondly, even if it was made available, the cost will be extremely high which will not be affordable given the economic disproportionality that persists in India. We do not have enough funds for purchasing it for the entire population.
Cluster Testing & COVID-19
Cluster testing mainly as the name suggests deals with forming clusters of cases of disease at a definite geographical location which breaks the chain of transmission of the disease. Like in the case of COVID-19, the states and country would limit and block all the borders national and international, between countries and states. After sealing the boundaries, the local authority would clampdown on movement and intensive screening would take place in all the places, with particular focus on the hot spots i.e. red zones of that particular area. Social distancing will prevail among the human and extra precautionary measures will be taken by authorities. The people forming each cluster will be scrutinized on the basis of their symptoms, travel history, immunity level, and other related aspects which can be useful for detecting the cases.
Hence, the overarching concept of cluster testing is dividing the nation into innumerable clusters of different geographical locations and conducting surveys.
Indian Perspective
Cluster testing in India happens using the anti-body tests, which have been approved in India by the Indian Council of Medical Research (ICMR). On 11th April 2020, Gangakhedkar stated[4] that India wishes to use the speedy and fast diagnostic tests in the places which have been shortlisted as a hotspot. This will help us to understand the number of people infected and we can also compare the results on a day to day basis. The epidemiologists of ICMR also contended that healthcare workers should also be tested in order to check whether they are positive or not. If they are tested positive but are negative in RT-PCR tests, then they are immune to virus. RT-PCR is Real Time-Polymerase Chain Reaction is a nuclear-derived method for detecting the presence of specific genetic material from any pathogen, including a virus.[5] Other states like Kerala and Rajasthan have also shown faith in the testing as the test being new and first-generation, will work effectively and become better with time. It will help to isolate patients who have tested positive.
States like Rajasthan, which was once the highest contributor for the number of cases in India, has reported successful of cluster testing. By adopting cluster testing, the number has fallen down hugely. The strategy was three-pronged, firstly, it included the strict implementation of curfew, locking down all boundaries of the containment zones and guaranteeing zero vehicular movements. Secondly, the task was to identify major potential clusters and conduct intensive testing and possibility of contact i.e. any traveller etc. The third step was a strict screening task to cover the entire population to detect influenza-like symptoms. This was later referred to as ‘Bhilwara Model’.[6] Similar successful case has also been found in Indore, Madhya Pradesh.[7]
However, according to the researchers and analysts, they estimated that for a population of 256 individuals, only 7.3% test on an average can be conducted, in a situation like India. Also, in such tests with a prevalence of 1%, the probability of detection of 5% where 95% of the probability of false confirmed cases of 4%.[8] They also concluded that in a population like India, it will be leading to high costs which are currently not possible for India at this stage.
Around the world
When we see across the globe, the results have been poor in the United Kingdom, Spain and the Czech Republic. UK government decided to apply the cluster testing using anti-body to know the widespread of the disease so that the process is fast and recovery is smooth and speedier. After the study which was performed by the Oxford University, where multiple clusters were tested, but it was found that none could perform well. It gave false results and most of them were negative. Later, the UK cancelled the decision of cluster testing and had to recover the heavy costs of testing kits. Similar failures have also been reported in Spain, Czech Republic and Slovakia.
If we see on another side, South Korea and Taiwan have witnessed a successful report on the cluster testing. The famed “Korean Model” is based on concentrated testing of hot spot area by forming clusters. At the beginning only, Korea had found out that the major reason for the spreading of coronavirus was due to the spread of certain religious cult group. They had huge gatherings in a closed space where people were closely in contact with each other, violating the basic norm of social distancing. The group was targeted and the names of all the members were listed, their locations were tracked and tests were conducted. All borders were sealed and so that there is no one entering the marked geographical area. There were a good number of increased confirmed cases and later in the very initial stage, Korea adopted the cluster testing which helped in finally flattening the curve of the positive cases. From March 1, 2020, till May 4, 2020, the number of tests conducted went from 98, 921 to 6,33,921 on May 4, 2020[9]. Dr. Roh Kyoung-Ho from National Health Insurance Service Ilsan Hospital said,
“Blocking off certain areas and stopping movement was what people did in the Middle Ages when they were dealing with the Black Death.”[10]
The second example for the success story of cluster testing is of Taiwan, where they acted upon the virus even faster. Singapore, along with Taiwan and Hong Kong, offers successful approaches, in battling a pandemic that has infected the whole world. It has been quite a few months that we have been attacked by the virus but these three Asian societies have recorded a very low number of deaths although the risk is still huge from the people emerging from United States, Europe etc. It is observed that early intervention is the key. The huge precautionary measures taken, the compulsory quarantines and meticulous social distancing has helped immensely to these locations. Taiwan started screening people when the spread was not even confirmed and admitted by China. It started testing passengers from Wuhan when the world did not even know that coronavirus is going to spread among humans. In January end, it suspended all flights to China, even when WHO was against it. Where on April 20, 2020, the number of reported cases was 1638 and now on May 5, 2020, was 560[11]. The reason for this huge decline is that everything is coordinated by the government who are willing to be fast and be transparent in all aspects[12].
However, the WHO has ruled and decided against the application of this cluster testing as the tests will cross-react with pathogens including the human coronavirus and tend to give false confirmed results[13]. On April 8, 2020, WHO briefed that antibody test kits detect the presence of the virus in the second week of the infection, hence cannot be used as a confirmatory test in this situation where the stage is deteriorating each minute. There is no evidence to support that the usage of the rapid diagnostic test will be able to predict the immunity of any person to the spreading virus.
Conclusion
Therefore, after researching the ways and aspects of cluster testing, we see there are various pros and cons for this concept. Various nations have tried and tested this concept, and some have failed as well. Before applying this test, the country or state should take care of the major factors involved in the process of conducting cluster testing and access its own condition to it either perform or not. Cluster testing requires a lot of precautionary and voluntary care from all side i.e. the public and the government. Lastly, we should keep in mind the possible ways of safeguarding ourselves in this COVID-19 is self-care and awareness.
[1] Advisory & Strategy for Use of Rapid Antibody Based Blood Test, Indian Council of Medical Research, (May 5, 2020) available at this link .
[2] F. W. Wilmink & H. T. Uytterschaut, “Cluster Analysis, History, Theory and Applications”, available at this link.
[3] N. Vuokko and P. Kaski, “Testing the Significance of Patterns in Data with Cluster Structure”, (2010) IEEE International Conference on Data Mining, Sydney, NSW, 1097-1102, available at this link.
[4] Swagata Yadavar, ‘India will use rapid antibody tests in Covid clusters even after WHO advised against it’, The Print, (Mayt 06, 2020) available at this link.
[5] Nicole Jawerth, ‘How is the COVID-19 Virus Detected using Real Time RT-PCR?’, International Atomic Energy Agency, (May 5, 2020), available at this link.
[6] Centre may adopt Bhilwara model to contain spread of Covid-19 in other hotspots, The Economic Times, (May 4, 2020), available at this link.
[7] Diagnostic Study Report Pharmaceutical Cluster at Indore (Madhya Pradesh), (May 6, 2020) available at this link.
[8] Bindu Shajan Perappadan, ‘Coronavirus | Rapid antibody testing for hotspots first, says ICMR’, The Hindu, (May 6, 2020) available at this link.
[9] Health & Pharmaceuticals, State of Health, ‘Cumulative number of coronavirus (COVID-19) tests conducted in South Korea from January 23 to May 4, 2020’, available at this link.
[10] Kelly Kasulis, ‘South Korea’s coronavirus lessons: Quick, easy tests; monitoring’, Aljazeera, (May 05, 2020) available at this link.
[11] Taiwan Centre for Disease Control, (May 4, 2020), available on this link.
[12] Tracking the Coronavirus: How Crowded Asian Cities Tackled an Epidemic, The New York Times, (May 6, 2020) available at this link.
[13] Id. at 7.
