What is known about COVID-19 continues to change, and I thought it might be useful to send out an update. But for now, please continue to schedule Virtual Visits if you have current symptoms of COVID-19, need testing for active infection, or would like the blood test for antibodies. And as before, please continue to schedule virtual visits for all your general primary care needs. We are scheduling “check-in” visits if your “check up” is overdue to give us a chance to review your care and to provide refills. This visit will not be billed as a “physical”, and I am recommending that you plan to come in for your routine “check up” when we are back in the office.
I am still recommending all of us do our best to avoid exposure to anyone outside of our homes. I want to thank all of you for the opportunity to provide your care virtually even though I think that in-person care would be better. I continue to be hopeful that the office will open soon, but cannot give you a date that any of us will feel safe. I imagine that a lot of us will want to continue to our interactions virtually for a long time, and of course these virtual visits will be fine with me whenever it makes sense. I am hopeful that we will start to see some patients in the office sometime in June, or maybe July.
What is the difference between the nasal swab (RT-PCR) and the blood test for IgG antibodies?
The nasal swab indicates the presence of virus particles in your nose, and indicates that you are actively sick. A positive result on the nasal swab means the person is likely to be contagious, and should be quarantined even if they are asymptomatic. Ideally, these patients will not leave quarantine until another nasal swab has come back negative. The blood test for IgG antibodies shows us something very different. If the person is generating IgG antibodies (a positive test), their immune system has seen this disease, and has successfully fought back. Antibodies should help prevent reinfection.
Can people who have antibodies get reinfected?
This disease is too new to know the answer. I believe that antibodies to COVID-19 will provide some protection. But there have been reports of patients who became ill with COVID-19, who appeared to recover fully including developing an antibody response, and then later became ill again. This is unusual in that with most other diseases, when someone makes IgG antibodies against that disease, it means that the person has recovered (or been vaccinated) and cannot get reinfected. However, it appears that COVID-19 is different, and antibodies may not prevent reinfection. Researchers are now trying to clarify the degree of immunity associated to COVID-19 antibodies. But a conclusion I feel we can confidently make is that once a person is making antibodies, you will know that they have successfully fought off this disease once, and are very likely to be able to handle a reinfection, should that ever happen.
Is the Quest antibody test accurate?
There has been a rapid growth in companies producing a COVID-19 antibody test, and accuracy is critical to successful reopening of society. Please see the information provided by Quest Diagnostics Lab:
Quest is using a test manufactured by Abbott, who has reported their accuracy through an internal study of 1,200 patients who were tested after 14 days of symptoms which showed Sensitivity of 100%, and Specificity of 99.5%. If these numbers are accurate, a “negative” result would mean that you definitely do not have immunity, and you continue to be vulnerable to this disease. And if you have a “positive” result, you are very likely to have antibodies and some protection. However, because of “false positives”, 8.6% of the people who are “positive” will not have antibodies at all (because there is an 8.6% false positive rate when the prevalence of disease is 5%, and a specificity of 99.5%). Even though these numbers have not been fully evaluated by the FDA due to time constraints, I have confidence that both Quest and Abbott are sufficiently careful about quality to continue to recommend that we use this test to learn about our immunity. LabCorp also does “serology” testing, but have not disclosed their Sensitivity or Specificity data. If new information becomes available on the testing, I will be sure to put it on my website (springvalleyim.com)
For more information, please see these comparisons of the accuracy of the different manufacturers of the antibody tests:
And this is a white paper from Johns Hopkins which thoroughly describes how we should approach Serology testing to help respond to this pandemic: