Testing for Covid-19
The PCR nasal swab is best performed within the first 24-48 hours when symptoms first appear. If it not done properly or at the early stages of the virus it will show a false negative.
Many of the labs doing the antibody testing have only a fifty to eighty percent accuracy rate according to the CDC. According to the CDC in a population where the prevalence is 5%, a test with 90% sensitivity and 95% specificity will yield a positive predictive value of 49%. In other words, less than half of those testing positive will truly have antibodies. The higher specificity the more accurate the test.
This means that even though you do the antibody test you still have to practice social distancing and wear a face mask. Even though you showed positive you also can get re-infected. It is shown in South Korea that 600 people have gotten re-infected. This can be due to the virus mutating or inaccurate testing.
Over the course of an infection, the immune system produces different types of antibodies including IgM, which develops early in the immune response and is not typically long-lasting, and IgG, which develops later and may be a possible marker of immunity. Antibody testing can provide important information about the different stages of one’s immune response to the COVID-19 virus.
When to get tested:
The timing and type of antibody test affects accuracy. If you have testing done too early in the course of infection, when the immune response is still building up in your body, the test may not detect antibodies.
Who should get tested?
While everyone is a candidate for COVID-19 antibody testing, consider testing if you:
· Believe that you may have been exposed to the coronavirus based on your previous signs and symptoms (such as fever, chills, cough, difficulty breathing, loss of taste/smell, muscle pain, headache, diarrhea, sore throat, fatigue, rash, etc.)
· Have been in close contact with an individual suspected of or confirmed to have COVID-19
· Have tested positive for COVID-19 and have recovered
How do antibodies work?
When exposed to a virus, your immune system develops antibodies against it, which may protect you from future infections. Antibodies (also called immunoglobulins), are protective proteins that recognize and latch onto antigens to remove them from the body. IgM and IgG antibodies both play key roles in the body’s immune response.
After a viral infection starts, different types of antibodies are produced in different stages. For example, IgM antibodies are typically detected earlier in the course of an infection whereas IgG antibodies generally develop later. When measured together, these antibodies can provide a comprehensive picture of one’s immune response. Of all of the antibodies, IgG is the best marker to indicate exposure to SARS-CoV-2. Typically, IgG will be detectable in the blood for months or even years after the resolution of an infection.
Is antibody testing a diagnostic test?
No. Antibody testing is not a diagnostic test to determine if you have an acute infection, but will tell you if you have developed antibodies against the virus. Until we learn more, antibody testing should not be used to change recommendations on social distancing, personal protection (face covers/masking), or work-related polices. It is vital to continue to follow COVID-19 guidelines from the Centers for Disease Control and Prevention until further notice. If you feel sick and are looking to confirm an active COVID-19 infection, please contact your local health department or healthcare provider to seek appropriate medical attention.
What do test results mean?
If test results show that you have antibodies, it indicates that you were likely exposed to COVID-19 at some time in the past. It may also mean that you have some immunity. But the World Health Organization (WHO) cautions that there is a lack of evidence on whether having antibodies means that you are protected against reinfection with COVID-19. The level of immunity and how long immunity lasts are not yet known. Ongoing studies will eventually reveal more data.
Do test results correlate with the severity of the disease?
No. In fact, results may indicate that you were infected with the SARS-CoV-2 virus even if you did not show any symptoms whatsoever. A person who was hospitalized in critical condition and a person who had barely a slight cough could both show antibodies to this virus.
Can a positive antibody test ensure immunity?
Because this virus has only recently come into existence, scientists are still learning about the human immune response to the disease. Although the presence of antibodies against SARS-CoV-2 suggests immunity, it has not yet been proven. It is possible for immunity to be partial, or wane over extended periods of time.
How accurate is antibody testing?
Since the SARS-CoV-2 virus is structurally similar to some other viruses, there is a very small chance of a false positive test the results can be positive even if the person has not had SARS-CoV-2 virus but has built immunity to a different virus, such as SARS-CoV-1. Also, a negative result may occur if you are tested early in your illness and your body has not had time to produce antibodies to infection.
How can I get tested?
Call the office 970-926-7606 to schedule a blood draw. I am currently do the 3 different antibody test IGA, IGM & IGG.
