A COVID-19 Infection with No Symptoms?

As the coronavirus disease (COVID-19) circulates across the globe leaving clusters of infection in its wake, the scientific community has begun to question how it is possible that the virus is spreading so quickly and ferociously throughout the population.

As of the morning of April 7, 2020, more than 1.36 million global citizens were reported to have tested positive for the COVID-19 virus. However, the actual number of people who have contracted the virus is essentially unknowable. This is, in part, due to a gap in testing supplies, but also due to the fact that many with COVID-19 may be asymptomatic (meaning without symptoms) and not seek testing.

How is it possible to have the novel coronavirus but not have any symptoms? Read on to learn more about the nature of transmission of the novel coronavirus, and what we know so far about cases that are asymptomatic.

How is the novel coronavirus being contracted?

Whether you are symptomatic or asymptomatic, when it comes to developing a COVID-19 infection, you must first come into contact with an “infectious dose” of viral cells. These viral cells must then enter your body and begin replicating. Scientists believe the novel coronavirus is being transmitted a few different ways:

• Transmission through respiratory droplets: This occurs when you are within close enough proximity to someone (approximately three-and-a-half feet) who is actively coughing or sneezing, and a droplet of their saliva is expelled and is then transferred into your mouth, nose, or eyes. Respiratory droplets generally can travel up to six feet before they succumb to gravity.
• Contact transmission: This occurs when a respiratory droplet from an infected person’s cough or sneeze lands on a surface, and then you touch the surface and proceed to touch your mouth, nose, or eyes. The novel coronavirus has been shown to persist on certain surfaces for up to three days, so contact transmission is likely a formidable form of viral spreading, particularly in densely populated settings.
• Airborne transmission: A question of airborne transmission has been raised and is actively being studied. When a virus is truly airborne, its particles can remain suspended in the air for long periods of time. These particles can travel through the air and be conferred to others who are more than three feet away. In this way, the novel coronavirus could be easily and rapidly transmitted by simple processes such as talking or even breathing. In medical settings, the novel coronavirus can be “aerosolized” in this manner during certain procedures such as intubation, suctioning, nebulizing, mechanical ventilation, or performing CPR.
• Fecal-oral transmission: One study has found that the virus is present in the feces of COVID-19 positive patients, meaning that another possible route of transmission is fecal-oral, wherein infectious viral particles in the feces reach the mouth, usually due to improper handwashing practices.

How can the novel coronavirus be detected?

Regardless of how you contract the virus, its presence is assessed in the same way. When the virus has replicated to a certain extent in your body, it can be detected using a swab that is placed either into your nose or the back of your mouth, and then identified in a laboratory process known as a polymerase chain reaction (PCR). If not enough virus has replicated yet, it is possible to get a “false negative” test; however, it is unlikely to get a “false positive.”

Can I test positive for COVID-19 before I develop symptoms?

New research reveals that it is quite possible for the novel coronavirus, also known as the SARS-CoV-2 virus, to be present in your body and detected via testing before you have any symptoms, a state known as “presymptomatic.” A study conducted by researchers in Singapore and China examined the average incubation period of the virus (which is the amount of time that it takes between coming into contact with the virus and developing symptoms of an infection) and its pattern of spread through the community. They found that, based on the rate at which viral clusters are emerging, the virus is likely being transmitted about 2.55 to 2.89 days before its new host develops symptoms.

Is it possible to have the virus and never develop symptoms?

Resoundingly: Yes. It is possible to have the novel coronavirus and have no symptoms at all. This asymptomatic classification goes beyond the designation of “presymptomatic,” as there have been people who have tested positive for COVID-19 (whether through routine screening or contact tracing) who have never gone on to develop any symptoms. Asymptomatic people who have the novel coronavirus likely quietly mount an immune response and then clear the virus without it ever registering as a disease state.

A harder question to answer is just how many people may currently have, or have recovered from, an asymptomatic infection. The evidence on this is variable:

• Medical data collected from passengers of the Diamond Princess cruise ship showed that 18% of passengers who tested positive for COVID-19 were persistently asymptomatic.
• According to a recent interview with the director of the U.S. Centers for Disease Control and Prevention (CDC), up to 25% of COVID-19 cases may be asymptomatic.
• Earlier data cited by the CDC indicate that up to 13 percent of children could have asymptomatic infections.
• A study of 36 children in China showed that 28 percent of COVID positive children were asymptomatic.
• Recent reporting on testing done in Iceland indicates that up to 50% of the positive COVID-19 infections detected in Iceland have been asymptomatic.

As these numbers regarding asymptomatic infections vary widely, more testing and research are certainly needed. More information emerges by the day. It may be that, ultimately, the only way to truly assess the magnitude of asymptomatic COVID-19 infections within the population is retroactively, by administering a population-wide blood test that examines antibodies that have been produced in response to the virus.

What to do if you are concerned you may be an asymptomatic carrier of COVID-19

Given the high transmissibility of the virus, coupled with the possibility of having an asymptomatic infection, it is easy and understandable to be concerned about whether you fall into the “infected, but unaware” category of the COVID-19 disease population.

If you are concerned, you may be able to access an on-the-spot COVID-19 test to get clarity, but most tests are being reserved by health care systems for patients who are displaying symptoms. In the future, though, you may be able to get a serology test to check for evidence of a past infection.

For now, it is best for everyone to presume that they are asymptomatic carriers of the virus, and to act accordingly. Rest assured that you can do your part to control the spread of the disease by following these simple steps:

• Wash your hands frequently, with soap, for 20 seconds at a time
• Cover your mouth when coughing or sneezing
• Try to avoid touching your face as much as possible
• Clean commonly touched household or office surfaces frequently
• Maintain a six-foot distance between yourself and others
• Wear a face covering when in crowded public places

For more information about what you can do to slow the spread of the virus, regardless of whether or not you may be an asymptomatic carrier, visit https://www.coronavirus.gov/.