Are inadequate testing techniques causing 'silent carriers' to spread COVID-19?

Dormant carriers of the novel coronavirus COVID-19, or “silent carriers”, as they are being dubbed show no evident symptoms of the virus or display symptoms very later on, may account for almost one-third of the total positive cases, the South China Morning Post reported.

The portal further claimed that these documents were classified.

By the end of February 2020, around 43,000 people had tested positive for the virus in China, but remained asymptomatic.

Even though the authorities had placed them under quarantine, these people were not included in the official tally. During that time, government sources claimed 80,000 were infected.

With the incubation period lasting for as long as three weeks in rare cases, it’s hard to ascertain the role played by silent carriers.

With different tally systems in place, countries have taken different approaches to count their cases.

The World Health Organisation claims that people who test positive with or without symptoms shall be included in the tally of confirmed cases.

South Korea has followed this calculative model. However, China changed its approach starting February 7, and started to include people in the tally only if they displayed considerable symptoms.

The model followed by China and South Korea includes testing anybody who may have come in contact with a person carrying the coronavirus, which helps in consolidating the numbers accurately.

However, many countries around the globe have opted for testing only people with symptoms, explaining why the number of cases have been rising tremendously in European countries like France and Italy.

The WHO had earlier claimed that the transmission from and among asymptomatic people was “extremely rare”. However, their recent report claims that one to three per cent of coronavirus transmission is caused by asymptomatic patients.

The major gap between cases counted in China and the rest of the world may be due to the different approach at testing patients.

Due to the extensive testing undertaken in South Korea, more than 20 per cent cases were asymptomatic. This could explain how the country was able to effectively contain the spread of the virus.

Italy, which has surpassed the Chinese death toll and is now being called the new epicentre of the virus has almost 44 per cent asymptomatic cases. The intensity of the havoc caused by the virus in the country may be attributed to the fact that majority of the testing is limited to people who show symptoms.

The number of asymptomatic cases and the health risk they post to others may be much higher than anticipated. For instance, Hong Kong recorded 138 cases of the virus, out of which 16 showed no symptoms.

This is in stark contrast to the official data released by China, for they claimed only 889 people were asymptomatic out of the 44,672 cases.

Even though the WHO claims that dormant carriers were not a key factor in the transmission, it seems like the role played by such carriers may have been swept under the rug.

Before the virus was identified, it was referred to as a pneumonia outbreak, for the symptoms were similar. A reported obtained by the South China Morning Post claimed that undocumented cases that displayed pneumonia like symptoms were responsible for 79 per cent of the documented cases in Wuhan.

Another study undertaken by the University of Texas at Austin claims that asymptomatic or pre symptomatic patients were responsible for at least ten per cent transmission in 93 Chinese cities.

As of now, based on the Johns Hopkins University tracker, at least 341,000 people have been infected with COVID-19. Around 14,700 have died.

Starting today, more than 750 million people in India have been placed under lockdown until March 31. Restrictions are travel, work, and movement based.

The US recently reported 400 deaths owing to the virus.