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Asymptomatic Carriers: Can They Unknowingly Be Spreading COVID-19?

Asymptomatic Carriers: Can They Unknowingly Be Spreading COVID-19?

A retrospective review published in the Annals of Internal Medicine by the Scripps Research Translational Institute claims that 30% to 45% of COVID-19 patients were infected by asymptomatic carriers. This recent discovery is pretty alarming. Is there asymptomatic transmission of the coronavirus disease?

Is There Asymptomatic Transmission of the Coronavirus Disease? What Does the Study Say?

Previous information about asymptomatic carriers said that the possibility of them spreading the virus is “extremely rare.” The study, which reviewed data from 16 groups of COVID-19 patients, says that it is much higher than previously known.

According to Dr. Eric Topol, founder of the institute and one of the paper’s authors, “The range we found is extraordinarily high, that means the range of what can happen with SARS-CoV-2 is from no symptoms to [death]. That’s not at all similar to any virus or pathogen we’ve experienced that has killing potential in the past. What we have here is an extraordinary spectrum, including this quiet, stealth mode of infecting somebody.”

The authors of the study, Dr. Topol and Daniel Oran, based their conclusions on diverse cohort studies that took into account symptomatic and asymptomatic patients. One of the results they studied was on the residents of a town called Vo, in Italy.

Researchers sampled 2812 residents in the first sampling, and 2343 during the second sampling. In the first group, 73 people tested positive. Of them, 30 (or 41.1%) were asymptomatic. In the second group, 29 people tested positive, with 13 (44.8%) being asymptomatic.

Is There Asymptomatic Transmission of the Coronavirus Disease? Other Studies Support the Findings

Their results are supported by other studies that show asymptomatic patients having the same amount of viral load as symptomatic patients. People with a high viral load are more likely to be infectious compared to those with a lower viral load.

Dr. Topol adds that there is also the possibility of the virus causing damage without any outward symptoms. According to data, 76 out of the 331 people on the Diamond Princess cruise ship showed signs of lung damage, but no outward symptoms.

Dr. Topol continues, “Basically, the reason why we have to all wear masks—because nobody knows who is an asymptomatic carrier. The person doesn’t know it, and the person’s contacts don’t know it. That has enormous implications, and it’s an area we need to study more, on how to test people without symptoms on a very large scale, to understand these people better and follow them to determine precisely their ability to transmit.”

Woman in Italy Received 6 Doses of COVID-19 Vaccine At Once

Is There Asymptomatic Transmission of the Coronavirus Disease?

While it seems that Dr. Topol’s findings show asymptomatic transmission of COVID-19, other medical experts beg to disagree. Maria Van Kerkhove, a WHO official and epidemiologist, added that asymptomatic transmission is rare.

Van Kerkhove said, “From the data we have, it still seems to be rare that an asymptomatic person transmits onward to a secondary individual.” She continues, “We have a number of reports from countries who are doing very detailed contact tracing. They’re following asymptomatic cases, they’re following contacts, and they’re not finding secondary transmission onward. It is very rare — and much of that is not published in the literature.”

However, her statements have sparked debate. Some groups are saying that wearing masks and practicing social distancing are not necessary because of her remarks.

Soon after, Van Kerkhove backtracked on her comments. She said that her statement was based on smaller studies, and should not be taken as WHO’s recommendations. People should still follow the WHO protocol when it comes to preventing the spread of the disease.

A number of studies have described individuals who were asymptomatic at the time of testing but upon following up, they were found to be “pre-symptomatic” and they would eventually go on to develop COVID-19 symptoms.

Is There Asymptomatic Transmission of the Coronavirus Disease? What does the WHO have to say?

Because of the resulting confusion and conflicting information, the WHO released a statement in an attempt to clear things up. In her statement, Van Kerkhove shared that “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 people who don’t develop symptoms, and to truly understand how many people don’t have symptoms, we don’t actually have that answered yet.”

She continues, “We do know that some people who are asymptomatic, or some people who don’t have symptoms, can transmit the virus on. So what we need to better understand is how many of the people in the population don’t have symptoms and separately how many of those individuals go on to transmit to others.”

So is there asymptomatic transmission of the coronavirus disease? Van Kerkhove also clarified that asymptomatic transmission of the virus is still a “large unknown.”

Is There Asymptomatic Transmission of the Coronavirus Disease? What is the Verdict?

To put it simply, we do not really know the answer yet. The medical community needs to conduct more studies to find out whether or not COVID-19 can be spread by asymptomatic individuals. The current information is inconclusive.

Additionally, we have evolving information regarding COVID-19’s transmission. This mainly stems from the fact that COVID-19 is a very new virus, and researchers are still learning more about it every day.

While we are not certain on is there asymptomatic transmission of the coronavirus disease, the best way to prevent infection would be to take precautionary measures.

Given the large number of people who have no symptoms when they test positive for the virus, continued vigilance can not be overemphasized. These preventive actions can help lower your risk of infection and prevent the spread of the disease.

Here are some ways to lower your risk of being infected:

  • Wear a face mask when you go outside.
  • If you have to cough or sneeze, use a handkerchief or tissue.
  • Practice social distancing and avoid crowds or crowded places.
  • Wash your hands for at least 20 seconds as often as you can.
  • Avoid touching your face, especially if you have not washed your hands.
  • Be sure to eat right and engage in exercise to keep your body and immune system healthy.
  • If you can, try to stay at home to lower your risk of infection significantly.
  • Keep your surroundings clean and disinfect any areas that may be contaminated.
  • If you experience any symptoms, consult a doctor, and get tested.
  • As much as possible, avoid going in and out of the house to lower your risk of infection

Learn more about COVID-19 here.

Hello Health Group does not provide medical advice, diagnosis or treatment.


Nearly Half of COVID-19 Cases May Be Spread Asymptomatically | Time, https://time.com/5848949/covid-19-asymptomatic-spread/?fbclid=IwAR3k_hmsNlCwa-a0tGW3Dro6_l7SOAhdWAYfZ_l2Crm0GxkbRJoo8PXf9MU, Accessed June 10 2020

Are asymptomatic people spreading the coronavirus? A WHO official’s words sparks confusion, debate – The Washington Post, https://www.washingtonpost.com/health/2020/06/09/asymptomatic-coronavirus-spread-who/, Accessed June 10 2020

Asymptomatic Transmission, the Achilles’ Heel of Current Strategies to Control Covid-19 | NEJM, https://www.nejm.org/doi/full/10.1056/NEJMe2009758, Accessed June 10 2020

Coronavirus: Asymptomatic transmission still an ‘open question’ – BBC News, https://www.bbc.com/news/health-52977940, Accessed June 10 2020

Asymptomatic spread of coronavirus ‘appears to be rare,’ WHO official says – CNN, https://edition.cnn.com/2020/06/08/health/coronavirus-asymptomatic-spread-who-bn/index.html?utm_content=2020-06-09T03%3A29%3A05&utm_source=fbCNN&utm_medium=social&utm_term=link, Accessed June 10 2020

Viral dynamics in asymptomatic patients with COVID-19 – ScienceDirect, https://www.sciencedirect.com/science/article/pii/S1201971220303374, Accessed June 10 2020

Asymptomatic coronavirus spread: WHO clarifies comments saying “There’s much unknown” – CNN, https://edition.cnn.com/2020/06/09/health/who-coronavirus-asymptomatic-spread-bn/index.html?fbclid=IwAR34sCjCmxC_XD7LzdK9t1cHx8WzbIUUxFsex2-86tuvS2R1SGUJ_vHIC90, Accessed June 11 2020

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Written by Jan Alwyn Batara on Jun 10, 2020
Medically reviewed by Dr. Erika Caperonce