Why COVID-19 clusters should be identified? | 5th April 2020

Spread the love

Do not wait; the time will never be ‘just right.’ Start where you stand, and work with whatever tools you may have at your command, and better tools will be found as you go along.– George Herbert

“Why must COVID-19 clusters be identified?



Why must COVID-19 clusters be identified?


Can infected individuals be tracked and quarantined quickly with the help of contact tracing?

SYLLABUS COVERED: GS 1:3:Demography:Population:Cluster


Around 9,000 people from across the country, Indonesia, Malaysia, Thailand and Saudi Arabia had attended a gathering at the Alami Markaz Banglewali Masjid, the headquarters of the Tablighi Jamaat, in the Nizamuddin area of Delhi in March.

Tamil Nadu, for instance, has identified all 1,103 people (from the State) who attended the conference in Delhi, helped by cooperation of the participants themselves.

Several State governments have struggled to identify the participants as some of them switched off their phones or have simply gone off the radar.


#In a paper published in The Lancet journal by the Singapore 2019 Novel Coronavirus Outbreak Research Team, the process of discovering clusters is described in detail (see graphic).

#The graphic shows one such cluster of cases which originated in a company conference in Singapore.

#The conference that happened between January 20 and 22 was attended by 111 participants from 19 countries and at least one of them was from Wuhan, China, the epicentre of the novel coronavirus outbreak.

#Part B of the graphic shows detailed activity trails of all the primary, secondary and tertiary contacts.


  • A disease cluster is defined as “an aggregation of cases in an identifiable subpopulation.” .
  • The word ‘cases’ in the definition stands for people with similar symptoms or a medical condition and ‘subpopulation’ points to those who share or belong to the same space, time, family, workplaces, etc.


  • Reports show that the novel coronavirus can travel about six feet from a diseased person and cause infection between two and four individuals.
  • When people congregate in a place — typically for worship/shopping/commute — the chance of a disease spread multiplies, resulting in a cluster of cases.
  • All patients who belong to a disease cluster need not have shared space and time.
The size of a disease cluster could vary widely from just four cases to as many as 5,000 depending on the place visited by the infected individuals.


A person who picks up the infection from a co-passenger during a flight may infect a taxi driver who picks him up from the airport.

Such secondary transmissions also belong to the same cluster with the primary source being the passenger.

The cluster keeps growing as the driver could infect a family member, the passenger could infect a nurse in a clinic after developing symptoms and so on.



  • Health workers often stumble upon clusters accidentally.

On February 4, Malaysia declared a person who had been to the conference as a COVID-19 case. Singapore authorities were alerted.

The health workers contacted the other participants and quarantined them.

  • Then they mapped their secondary and tertiary level of contacts (all those not infected by the primary case) — as shown in Part A of the graphic.
  • Then they were tested and isolated if necessary.


  • Once they found a set of cases among those who attended the conference, it was identified as a cluster.
  • In parallel, the activity trails of the primary infected during the conference and also of others outside the conference were pieced together like a puzzle.
  • Such mapping also helps in calculating the time taken by each individual to show symptoms, or to be declared as suffering from COVID-19, from the time he or she was infected.

Those who had come in contact with the infected during such activities, for example the hotel workers, were called in for testing. This is called contact tracing.


  • Discovering a cluster is akin to a fire alarm going off. Every moment wasted will spread the fire further.
  • The faster the infected individuals are identified and quarantined, the lesser the number of future contacts.
  • Sources said Andhra Pradesh is tracing the digital footprints of those who tested positive for COVID-19.

As those who were infected respond differently in each State, a common protocol cannot be followed and this has pushed the States to adopt various uncharted methods making the process challenging.


A group boarded a train to Erode, Tamil Nadu. One of the attendees, Navi Mumbai’s index patient, had visited Noor Masjid in Vashi, Maharashtra.

This led to a secondary transmission to six people, including the secretary of the mosque, his friend, son, grandson and maid and another person who was present at the mosque.

This leads to the possibility of a wide range of secondary and tertiary transmissions across many States of India.

      IASbhai Windup: 


Almost all countries have discovered a large cluster and in most of them, the number of COVID-19 cases shot up after identification of the infected and contact tracing began.

As of April 4, South Korea has mapped 83% of its cases to some clusters.

More than 51% of the country’s cases originated from the Shincheonji Church of Jesus.

And most of the infections were allegedly brought to the church by a 61-year-old woman who ignored her symptoms and attended the church.

Spread the love

You have successfully subscribed to the newsletter

There was an error while trying to send your request. Please try again.

IASbhai will use the information you provide on this form to be in touch with you and to provide updates and marketing.