Understanding The Differences Between COVID-19 Asymptomatic and Presymptomatic Conditions
COVID-19 Asymptomatic and Presymptomatic
: Recently, the ‘China owned’ WHO (or World Health Organization) , one of the main health entities with a track record for misinformation and fake news about the COVID 19 made yet more misleading information publicly when during a June 8 press briefing, Maria Van Kerkhove, PhD, the WHO's technical lead on the COVID-19 pandemic, said that asymptomatic spread of the coronavirus “appears to be rare.” https://www.who.int/docs/default-source/coronaviruse/transcripts/who-audio-emergencies-coronavirus-press-conference-08jun2020.pdf?sfvrsn=f6fd460a_0
That misleading official statement by WHO caused an uproar, contradicting what many public health experts have been saying for months about asymptomatic spread.
Additionally in trying to clarify her misleading statements, Van Kerkhove said that when health officials review cases that are initially reported as asymptomatic, "we find out that many have really mild disease." She revealed that there are some infected individuals who are “truly asymptomatic,” but countries that are carrying out in-depth contact tracing are not uncovering “secondary transmission onward” from those cases. “It is very rare,” she added.
Interestingly the WHO backtracked at a question-and-answer session the following day, STAT
reported, and Van Kerkhove stressed that the actual rates of asymptomatic transmission are not yet known. https://www.statnews.com/2020/06/09/who-comments-asymptomatic-spread-covid-19/
She said, "The majority of transmission that we know about is that people who have symptoms transmit the virus to other people through infectious droplets. But there are a subset of individuals who don not even develop symptoms, and to truly understand how many individuals do not have symptoms, WHO do not actually have that answer yet.”
Dr Anthony Fauci, MD, director of the National Institute of Allergy and Infectious Diseases said on June 10 that the WHO’s initial comment “was not correct and misleading.” Dr Fauci said 25% to 45% of individuals who are infected with COVID-19 likely do not exhibit any symptoms, adding, “We know from epidemiological studies they can transmit to someone who is uninfected even when they are without symptoms. So to make a statement to say that's a rare event was not correct and literally misinformation."
However it should be noted that one of the main confusion here is that the term "asymptomatic" has been used widely by both the general public and public health experts to describe two different groups of COVID-19 patients : individuals who are infected and truly asymptomatic, and individuals who are infected but are what medical experts call "presymptomatic" and there is a different between the two.
Differences between Asymptomatic and Presymptomatic
Typically, asymptomatic is when an individual does not exhibit any symptoms but is infected with the SARS-CoV-2 coronavirus. However, presymptomatic is the phase when an individual is infected and may be shedding virus but has not yet developed any symptoms. This is important in terms because, as the US CDC says, symptoms can show up in patients with COVID-19 two to 14 days after exposure. https://www.cdc.gov/coronavirus/2019-ncov/symptoms-testing/symptoms.html
Importantly, the term asymptomatic is not associated with time, while presymptomatic is.
Should a COVID-19 test comes back positive and the patient does not have symptoms, we do not know if they will remain asymptomatic the whole time, or develop symptoms within a day or so.
There is not much research that differentiates asymptomatic COVID-19 cases versus presymptomatic cases. The US Centers for Disease Control and Prevention (CDC) estimates that 35% of all individuals with COVID-19 are asymptomatic, but says that those individuals are just as infectious as those with symptoms. https://www.cdc.gov/coronavirus/2019-ncov/hcp/planning-scenarios.html
The US CDC also estimates that 40% of transmission happens before individuals feel sick. A research, published in the journal Science
, indicated that about 4 in 5 individuals with the SARS-Cov-2 coronavirus in China were likely infected by individuals who did not know they had the virus. https://science.sciencemag.org/content/sci/early/2020/03/24/science.abb3221.full.pdf
In daily lives, it is hard to tell the difference between both asymptomatic and presymptomatic individuals. Both types of carriers look and feel “normal” until in the case of presymptomatic infected individuals, symptoms develop.
However with PCR testing and specifically more widespread testing currently, physicians are finding individuals with a positive test who do not have any symptoms at the time of testing, indicating they are either presymptomatic or asymptomatic.
The polymerase chain reaction (PCR) test for COVID-19, which detects the genetic information of the virus (RNA), is to a certain degree sensitive enough. That means it has the ability to detect the coronavirus even in asymptomatic or presymptomatic individuals. It starts to pick up virus up to a week before symptoms develop, through the period of symptoms, and continues to detect particles of the RNA virus for up to and beyond six weeks after the patient has recovered.
Hence, in an individual not showing symptoms but who has been exposed to COVID-19, a PCR test can show whether they have the virus. After a positive test, if that person goes on to develop symptoms, they were presymptomatic at the time of the test; if they never develop symptoms, they're asymptomatic.
Individuals in the presymptomatic stage are highly contagious
. The peak of viral shedding occurs right before symptoms develop and immediately after, when the symptoms are still mild.
Dr Fauci also previously said that those who are presymptomatic are highly contagious. Individuals tend to be the most contagious before
they develop symptoms, if they're going to develop symptoms. But when it comes to asymptomatic patients, how much virus they shed and how contagious they are is still a matter of debate.
However from medical professionals’ perspective, it is critical to distinguish between asymptomatic and presymptomatic patients wherever possible, particularly when it comes to planning elective surgeries for patients who test positive for COVID-19 without symptoms.
There is information to suggest that if one is to intubate someone for a surgery in their presymptomatic stage, doctors may end up doing them harm and these patients will have the worse surgical and respiratory outcomes,. That's because, if the patient develops COVID-19 after surgery, they'll have the illness to fight as they recover. https://www.demedischspecialist.nl/sites/default/files/leidraad_preoperatieve_workup.pdf
Also there is a greater risk of transmission to health care workers because the viral load in the patient is the highest. https://www.apsf.org/covid-19-and-anesthesia-faq/
There’s still a lot to learn about how the SARS-CoV-2 coronavirus spreads, including the risk posed by both asymptomatic and presymptomatic carriers.
However in the meantime, wearing face masks and keeping a physical distance from others can help reduce the risk of infection whether an individual is symptomatic, asymptomatic, or presymptomatic.
For more about COVID-19 asymptomatic or presymptomatic
conditions and research, keep on logging to Thailand Medical News.