What do we know about COVID-19?
We know much but still lack a great deal of information regarding COVID-19 infections. For one, we know that patients above the age of 50 with co-morbid conditions such as heart disease, lung disease, diabetes, cancer, or autoimmune disease are at increased risk of complications. We know that many children and young people have asymptomatic disease. We know that those children and young people with asymptomatic disease can transmit the virus to other people.
Who should be tested for COVID-19?
Everyone with symptoms suggestive of COVID-19. This is somewhat unique in that COVID-19 can present as many different illnesses. Fever, cough, shortness of breath and loss of smell or taste are well documented. Gastrointestinal symptom presentation is not unusual so it too, can be a COVID-19 infection. Patients with upper respiratory, lower respiratory, gastrointestinal symptoms, fever, fatigue, headache, myalgias (muscle pain), all may be COVID-19 symptoms and should be tested. Close contacts of COVID-19 confirmed patients should be tested.
How can we test for COVID-19?
There are two general types of tests for acute infection with COVID-19. Both are looking for evidence of the presence of the virus. The RT-PCR test is the test performed most of the time and the problem is the lack of a point of care RT-PCR test. These tests are swabs taken and sent to laboratories for evaluation. The turnaround time ranges from 2-7 days, delaying decisions for recommendations on isolation, retesting, or return to work or active family activities. The second test for the presence of the virus is an antigen test. This test looks for a “piece” of the virus and if present means the virus or at least that part of the virus is present in the patient and that is consistent with an acute infection. The antigen test is a good test when positive but when negative, there is still a 30% chance of the patient having the illness so negative antigen tests need a RT-PCR test to confirm a true negative.
A related test is the IgM/IgG antibody test for COVID-19. IgM antibodies are formed by patients exposed to COVID-19 viruses as part of their recovery. IgM antibodies take 1-2 weeks to form. IgG antibodies are also formed in response to infection but take longer, up to 3-6 weeks to form. The antibody test is useful when someone has “recovered” from a possible COVID 19 infection. If the IgM antibody is positive but the IgG is negative, than this is consistent with a very recent COVID-19 infection. If the IgM antibody is negative and the IgG antibody is positive, then this is consistent with a COVID-19 infection in the past but most likely not recently. If both are negative, then most likely no recent or past COVID-19 infection has occurred. Both antibodies could be negative for the first 2-3 weeks so a negative antibody test does not rule out an acute infection. Additionally, there is some cross reactivity with other coronavirus infections but a positive IgM suggests recent and most likely COVID-19 infection.
Summit Urgent Care Center offers both the antibody tests for COVID-19 recent or past infections and a rapid turnaround antigen test for current COVID-19 infection. Both tests take around 15 minutes for results. Due to the concerns that many COVID-19 tests are capable of a “false” negative tests, we recommend a PCR send out tests if the antigen test is negative. If the antigen test is positive, it is considered accurate and would confirm an acute infection.
