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Delhi Health Minister has said recently that source of COVID-19 infection in 50 percent of the cases in the national capital was unknown, adding that it was up to the Centre to declare whether the city had entered the community transmission stage. He also indicated that the assessment of the local administration points towards the “third stage of spread”.
What is ‘Community Transmission’?
- According to the World Health Organisation (WHO), 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 other words, community transmission or spread is said to be taking place when the source of the contagion is not known, i.e. when one is unable to trace an infection back to a carrier who has travelled in an affected area, or through contact with a person who has the disease.
- A state of community spread implies that the virus is now circulating in the community, and can infect people with no history — either of travel to or contact with affected people and areas. At this stage, it is theoretically possible for everyone to catch the infection.
What are the different stages of a pandemic?
- In the first stage of a disease that eventually takes the form of a pandemic sweeping the globe, cases are imported into a country in which the infection did not originate. An infection whose spread is contained within the boundaries of one or some countries is obviously not a pandemic. The first case of Covid-19 outside China was reported in Thailand.
- The second stage is when the virus starts being transmitted locally. 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.
- The third stage is that of community transmission.
- There is also a fourth stage in every pandemic. It is when the disease becomes endemic in some countries. The Indian government’s containment plan takes this possibility into account. Among diseases that are currently endemic in India — meaning they occur round the year across the country — are malaria and dengue.