Community spread of coronavirus: What is it, and what does it entail?

Understanding 'community spread' of coronavirus: what is it, what does it entail?

Community spread of coronavirus: In a situation of community transmission, it is theoretically possible for every person regardless of where they are from or whether they have been in contact, to spread the infection. (File photo)

The government is yet to confirm community transmission of the novel coronavirus (SARS-CoV-2), but experts feel that an announcement is now only a question of when, not if.

There are suggestions that community spread is already happening.

What is community spread of the infection?

The World Health Organisation (WHO) says community transmission “is evidenced by the inability to relate confirmed cases through chains of transmission for a large number of cases, or by increasing positive tests through sentinel samples (routine systematic testing of respiratory samples from established laboratories)”.

In the simplest terms, community spread is when you do not know the source of the infection — you are unable to trace it back to someone who has travelled in an affected area overseas, or got it through contact with someone who is infected.

Community spread implies that the virus is now circulating in the community, and can infect people with no history — either of travel to affected areas, or of contact with the infected person.

In a situation of community transmission, it is theoretically possible for every person regardless of where they are from or whether they have been in contact, to spread the infection.

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Community transmission of coronavirus: In Mumbai during the Janata Curfew on Sunday. (Express Photo)

So are all the cases in India so far traceable to a history of travel or contact?

Officially, almost all. But there have been a few cases in which the contact tracing has not been conclusive. Those cases serve as evidence that the infection could have reached the stage of community spread.

One example is that of a 20-year-old barber from Rampur in Uttar Pradesh who travelled by train from Delhi to Chennai. After he tested positive, the government was unable to establish a history of foreign travel or traceable first-level contact with a recent arrival in India from abroad.

The Health Ministry had recently issued a statement on the possibility of “community transmission” in Agra — scientists had, however, said that instead of the classic community spread, it was likely a case of local transmission at a community level.

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In the death that occurred in Mumbai on Saturday, that of a 63-year-old man who had been admitted to H N Reliance Hospital on March 19, state officials have been trying to track a relative or friend with a travel history. A top official said that the “likelihood of community transmission was high”.

It is also important to remember that testing in India has progressed slowly. A lot of experts believe that the reason India has not shown many cases is simply that the country has not tested enough people.

When can it be said that the virus is definitely in the stage of community spread?

Irrespective of what is being posted on social media and the apparent inevitability of community spread, the general public should wait for an official announcement, either from the ICMR or any other responsible government body.

There have to be several cases of untraced infection source to conclude definitively that the outbreak has moved to the next level.

As of Sunday afternoon, the government’s position remains that the outbreak is still in Stage II, that it is being transmitted locally.

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Community spread of coronavirus: Outside a testing clinic in New Delhi. (Express Photo: Tashi Tobgyal)

Local transmission means that the source of the infection is from within a particular area and the trajectory the virus has taken from one person to the next is clearly established.

What steps will be taken if — and when — the stage of community spread is declared?

India has been calibrating its response with the spread of the outbreak.

Restrictions on travel to China were imposed very early on, as the cases then were all imported from China. Later, as cases started being imported from other countries, flight and visa restrictions were put in place for those countries.

It has now shut itself to every country in the world because the virus has spread almost everywhere on the planet, even to remote Pacific Ocean islands. Large numbers of people are in government quarantine facilities, in home quarantine or under community surveillance.

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The lockdowns announced on Sunday, restricting movements to only essential services in 75 districts, appear to be a precursor to such a step nationwide in the event of community transmission.

How long before India enters the stage of community transmission?

We have to wait for the government's announcement.

The janata curfew, shutting down of trains and Metro services, and the lockdowns announced by states like Punjab and Rajasthan suggest it could be very soon.

Here’s a quick coronavirus guide for you to stay updated: Who all should be tested for Covid-19 and when? | How should you quarantine yourself? | How often (and how) should you clean your home? | What is the Janata Curfew announced by PM Modi? | Who are restricted from coming to India, and from when? | How long can the virus live on surfaces or in air around you? | Still more Coronavirus Q&A Explained news here