June 2, 2020
Summer is coming and things are slowly starting to open up. We are beginning to see more and more patients in the office but with social distancing, temperature check, symptom screening, masks/gloves and cleaning of rooms.
With the feeling that severe lockdown may gradually end with phased opening of services including hair salons, churches and restaurants, more patients are asking about antibody testing.
Antibody testing looks for IgM and IgG responses to virus. These are immunoglobulin responses and most look for the response to spike protein on virus surface. The IgM response peaks first and declines in about 4 weeks while IgG response peaks around 4 weeks and persists for some time. We do not know how long it lasts or what level is needed to prevent reinfection but so far there are no clear documented cases of reinfection!
If you have antibodies it means you have been infected with the virus and have devleoped an immune response. What we do not know yet is if you are totally protected from future infections or you have partial/minimal immunity.
Most people in United States are still going to test antibody negative and also in New York where we were an epicenter of disease. Here the positive rate has been about 15 % in surveys but only 3-4 % in California. This is a novel virus that has not been present before. We need to get immunity close to 70% in population to have herd immunity which is why we need a vaccine. Until then we all need to continue to wear masks, wash our faces and hands and socially distance.
Nancy Nealon MD