The Centers for Disease Control and Prevention announced Saturday that it has begun studies to determine how many people in the United States have already been infected with COVID-19.
The new testing will look for the presence of antibodies, which are specific proteins made in response to infections. The test results will be important in detecting infections in people who have had few or no symptoms of the virus.
Some health officials, including Dr. Anthony Fauci, the director of the National Institute of Allergy and Infectious Diseases and a member of the White House Coronavirus Task Force, believe that up to 50 percent of the people who have contracted the virus have had no symptoms while the had the virus.
Someone infected with the COVID-19 can show mild symptoms similar to a cold or have more severe symptoms like high fever, severe cough and shortness of breath, which often indicates a person has pneumonia. However, more scientists are saying that perhaps a larger number of people have virtually no symptoms at all when they have the virus.
Could you have had the disease in the past few months and not known it? Here’s what we know about spreading the virus, mild or no symptoms and if there’s a test that can tell you if you have already had COVID-19.
1. Could I have had COVID-19 in the past few months and not known it?
The answer is yes, you could have had the virus and not shown symptoms or perhaps had symptoms so mild you assumed you had a cold or allergy.
Robert Redfield, the director of the CDC, said last week that up to 25% of people who have been infected with COVID-19 may never show symptoms.
“We have pretty much confirmed” that “a significant number of individuals that are infected actually remain asymptomatic,” Redfield told NPR last week.
If a person is asymptomatic it means they have an infection but are not suffering any symptoms of the virus.
Fauci said Sunday during a briefing by the White House Coronavirus Task Force that he believes the number of people infected with COVID-19 but show no symptoms is likely “somewhere between 25 and 50 percent.”He emphasized that until more testing information is available, that estimate is a guess.
The list of symptoms that have been associated with the virus is not a small one. According to the CDC, symptoms such as a dry cough, fatigue, low-grade fever, body aches, nasal congestion and sore throat are the most common with COVID-19. In addition, symptoms such as the loss of the senses of taste and smell, diarrhea and the appearance of conjunctivitis – commonly known as “pink eye” – have also been seen.
2. Is there a test that can tell me if I had it?
These tests are different from the tests conducted now to find out if a person is positive for COVID-19. Those tests are called PCR and they look for the presence of the virus in people at the time they are tested.
If a person has had the virus and recovered, the PCR test would show no virus in the person. The PCR test result does not mean that the person never had the virus, only that there is no virus in them at the time the test was taken.
The tests the CDC began look for something different.
When a person is infected with a virus, the body begins to fight it by producing antibodies. Antibodies, which are a protein in the blood, will combine chemically with viruses to kill them.
After the virus is dead, some antibodies remain in the blood, ready to fight the virus should it return.
Antibodies have properties unique to the virus it is fighting and those properties allow scientists to develop tests to see if a person’s body has fought off a certain virus.
According to a story from STATnews.com, researchers at the Icahn School of Medicine at Mount Sinai in New York City have also developed tests that look for the antibodies created to fight COVID-19.
“It seems very easy to be able to say yes or no, somebody was infected or wasn’t infected,” Florian Krammer, a virologist at the Icahn School of Medicine, told Stat.
According to the article, Krammer and several colleagues posted a paper describing how they developed the test. The paper has not been through the peer review process yet.
A website Krammer’s group has started directs labs on how they can order the ingredients they need to conduct the tests. Other laboratories around the world are also developing antibody tests.
3. If I had no symptoms but had the virus, was I contagious?
Scientists believe that people without symptoms can spread the virus.”There’s significant transmission by people not showing symptoms," Stephen Morse, an epidemiologist at Columbia University, told Business Insider.
In the interview with NPR, Redfield said it appears people with the virus are most contagious about 48 hours before symptoms appear.
“This helps explain how rapidly this virus continues to spread across the country because we have asymptomatic transmitters and we have individuals who are transmitting 48 hours before they become symptomatic,” Redfield said.
A CDC study of coronavirus patients in a nursing home in Washington showed that of 23 people who tested positive for COVID-19, only 10 had shown symptoms on the day of their diagnosis. Of the 13 others, 10 developed symptoms a week after being found to be positive for the virus.
4. If I have mild or no symptoms, how am I spreading the virus?
The virus is believed to be spread by droplets that come from an infected person’s body. Even if you do not feel ill or do not have severe symptoms, you can have a high virus “load,” or amount of virus in your body.
People shed the virus (pass it to others) through touching their mouths or noses and then touching a surface where it can stay for minutes or hours, or by coughing or sneezing. Some researchers believe that just by being near someone and talking can spread the virus.
5. If I’ve had it, can I get it again? Researchers say that having the virus and recovering from it will likely give a person immunity from the new coronavirus, at least for a time.
"It is reasonable to predict we will have some immunity. To say you will have lifelong immunity? We just don’t know yet,” Frances Lund, professor and chair of the department of microbiology at the University of Alabama at Birmingham, told NBC News.
“But I think it’s a reasonable conclusion that you will have immunity for the rest of this season.”
Viruses can and do mutate in order to survive. If the COVID-19 virus does mutate, a person could get the virus again, albeit a slightly different version of the virus.