What do we know about pre-symptomatic and asymptomatic transmissions?
What do we know about pre-symptomatic and asymptomatic transmissions?
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People who have been infected with COVID-19 but don't have symptoms are considered "asymptomatic." People infected with COVID-19 whose symptoms have not yet developed are called "pre-symptomatic." Even as people who are asymptomatic and pre-symptomatic don't display symptoms, they are still infected with the virus, and have the potential to shed the virus. This means that people without symptoms can still spread the virus to others, even if they don't feel sick.
People who have been infected with COVID-19 but don't have symptoms are considered "asymptomatic." People infected with COVID-19 whose symptoms have not yet developed are called "pre-symptomatic." Even as people who are asymptomatic and pre-symptomatic don't display symptoms, they are still infected with the virus, and have the potential to shed the virus. This means that people without symptoms can still spread the virus to others, even if they don't feel sick.
Publication
What our experts say
People who have been infected with COVID-19 but don't have symptoms are considered "asymptomatic." People infected with COVID-19 whose symptoms have not yet developed are called "pre-symptomatic." Even as people who are asymptomatic and pre-symptomatic don't display symptoms, they are still infected with the virus, and have the potential to shed the virus. This means that people without symptoms can still spread the virus to others, even if they don't feel sick.
People who have been infected with COVID-19 but don't have symptoms are considered "asymptomatic." People infected with COVID-19 whose symptoms have not yet developed are called "pre-symptomatic." Even as people who are asymptomatic and pre-symptomatic don't display symptoms, they are still infected with the virus, and have the potential to shed the virus. This means that people without symptoms can still spread the virus to others, even if they don't feel sick.
Context and background
There is concern about transmission by people without symptoms because this makes disease prevention more challenging. For example, while it is a helpful public health measure to recommend that people self-isolate when ill, it is insufficient to stop the spread of the novel coronavirus when someone who never develops symptoms or who has not yet developed symptoms can still infect others. In some recent publications, it is estimated that 6-41% of reported novel coronavirus infections may be due to asymptomatic and/or pre-symptomatic transmissions.
There is concern about transmission by people without symptoms because this makes disease prevention more challenging. For example, while it is a helpful public health measure to recommend that people self-isolate when ill, it is insufficient to stop the spread of the novel coronavirus when someone who never develops symptoms or who has not yet developed symptoms can still infect others. In some recent publications, it is estimated that 6-41% of reported novel coronavirus infections may be due to asymptomatic and/or pre-symptomatic transmissions.
Resources
- A study about viral shedding and transmission of COVID-19 (Nature)
- WHO clarifies comments on asymptomatic spread of Covid-19 (STAT)
- Prevalence of asymptomatic SARS-CoV-2 infection (Annals of Internal Medicine)
- Asymptomatic Transmission, the Achilles’ Heel of Current Strategies to Control Covid-19 (NEJM)
- Estimating the extent of asymptomatic COVID-19 and its potential for community transmission: systematic review and meta-analysis (medRxiv)
- A study about viral shedding and transmission of COVID-19 (Nature)
- WHO clarifies comments on asymptomatic spread of Covid-19 (STAT)
- Prevalence of asymptomatic SARS-CoV-2 infection (Annals of Internal Medicine)
- Asymptomatic Transmission, the Achilles’ Heel of Current Strategies to Control Covid-19 (NEJM)
- Estimating the extent of asymptomatic COVID-19 and its potential for community transmission: systematic review and meta-analysis (medRxiv)
