Coronavirus outbreak: What are the stages of transmission and what they mean

India reported more than 850 confirmed cases of the coronavirus disease and 19 deaths on Saturday as the country entered the fourth day of the three-week nationwide lockdown.

The government has taken a slew of measures to step up against the spread of Covid-19, including announcing the 21-day lockdown across the country and the economic stimulus package.

As the numbers neared the 900 mark, many have expressed concern that the coronavirus epidemic could be advancing towards community transmission in the country.

The Indian Council of Medical Research (ICMR), the Union ministry of health and family welfare and members of Covid-19 task force have been said India is not in the dreaded Stage 3 or there is no community transmission of the coronavirus at the moment.

China, Italy and the United Kingdom have already reached Stage 3 of the pandemic and reported hundreds of deaths and ballooning cases of the coronavirus disease.

Here is what the four stages of the Covid-19 pandemic mean:

Stage 1

Stage 1 is when cases are imported from affected countries without any local origin and only those who have travelled abroad test positive for the respiratory illness. The disease does not spread locally at this stage.

Stage 2

This is the stage when local transmission happens and its source is known and can be located. At this stage, people testing positive have come in contact with a patient who has travelled outside the country. They are usually those in close contact with the patient such as family members or others who have been in touch with the infected.

Fewer people are affected at Stage 2 and it is easier to perform contact tracing and contain the spread via self-quarantining. India is currently in Stage 2.

Stage 3

This is the stage of community transmission and takes place when the source of an individual’s infection can’t be traced and isolated.

During this stage, those who have not been exposed to an infected person or anyone who has a travel history to affected countries still test positive for the coronavirus. The outbreak will spread fast in clusters once the community transmission starts.

Countries like Singapore, Italy and Spain are currently in Stage 3.

Stage 4

It is the most dreaded stage during which there are several clusters of the infection and it takes the form of an epidemic. Massive numbers are infected making it very difficult to control and contain the spread of the disease.

China has already been in Stage 4.