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Current Affairs

Asymptomatic people carry high viral load

Date: 12 August 2020 Tags: Miscellaneous

Issue

Evidence suggests that people without symptoms can and do readily spread coronavirus, and people are most infectious just a couple of days before symptoms show up. 

 

Background

One reason why containing novel coronavirus spread is challenging is that people who seem to be healthy despite being infected with the virus can spread it to others.

 

Details

  • It is during the presymptomatic phase when infected people don’t exhibit symptoms but do shed substantial amounts of virus.

  • A retrospective study of 303 symptomatic and asymptomatic patients infected with SARS-CoV-2 during March 6-26 has found definite evidence that people who do not exhibit symptoms carry the same amount of virus as those who are symptomatic. 

  • Of the 303 patients studied, 110 (36.3%) were asymptomatic at the time of isolation. The team found that only 21 of 110 asymptomatic patients subsequently developed symptoms.

  • This study thus provided the much-needed evidence that many people with coronavirus infection can remain asymptomatic for a “prolonged period”.

  • A review states that asymptomatic persons account for nearly 40-45% of SARS-CoV-2 infections. The review also said that such people transmit the virus for an extended period, perhaps longer than 14 days.

  • While the incidence of asymptomatic patients carrying high viral load raises the possibility of such people spreading the virus to others, the study did not determine this.

  • Both symptomatic and asymptomatic patients were isolated, thus providing no opportunity to study the chain of transmission.

  • Also, live virus was not cultured (grown) in labs to confirm the infectious nature of the virus. Hence, they note that detection of viral RNA does not equate infectious virus being present and transmissible.

  • The challenge with asymptomatic infection is the heightened risk of such people travelling freely and mingling with others thus spreading the virus to them, whereas those with symptoms are more likely to stay at home.

  • The combination of prolonged period of being asymptomatic and carrying similar viral load as people with symptoms would necessitate isolation of all infected people regardless of symptoms.