We strongly feel that antibody testing for COVID-19 should be available for patients during this pandemic. We are now able to perform in-office testing for the COVID19 virus and antibody tests for COVID-19 and results are available in less than one hour.
A positive IgM test suggests recent/active exposure or infection. A positive IgG test suggests prior/remote exposure or infection and possible decreased susceptibility to future COVID19 infection. It does not indicate the presence or absence of an infectious virus (which the nasal PCR swab for viral particles does). Keep in mind there may be a delay for antibodies to develop after exposure to or infection with the virus. This test is being distributed under Emergency Use Authorization by the FDA in the face of the current pandemic. Please call the office for more information.
The question of immunity
The unknowns begin with how much an immune response to COVID-19 tells us. Early studies suggest the production of IgM and IgG in COVID-19 patients typically occurs between 7 and 11 days after exposure. IgM antibodies appear first, followed by IgG antibodies. The presence of these antibodies indicates that a person has been exposed, and their immune system has reacted. The question that scientists are trying to answer is: can an immune person still get re-infected?
Often, but not always, the presence of antibodies corresponds to immunity to that agent. If that turns out to be the case for COVID-19, that would be extremely important. Early studies from China studied monkeys previously infected and cured of the virus. The results, which showed no recurrence of COVID-19 in the re-challenged monkeys, suggest some level of protective immunity after infection. That’s a very encouraging finding, but we don’t know yet whether that is true yet in humans. We certainly don’t know how long is the duration of immunity. If some level of protective immunity for people who’ve had COVID-19 does exist, serologic testing can help in multiple ways. It can help guide us as we try to figure out how, or whether shelter-in-place orders can be eased, more people can return to work, and children can return to school.
Widespread testing needed
Antibody testing can help us identify who in our community is at risk of developing an infection. Knowing how many people in a given community are still susceptible to the virus will be very important for us to decide what to do next winter. Together with sensible milder methods of physical distancing (maybe including masks) and proper testing and contact tracing of active infections, we might hope to resume activity in a more ‘normal’ way in the coming months if a substantial fraction of the population show immunity.
Some countries, like Germany and the United Kingdom, have even floated the idea of “immunity passports” that could be issued to people based on the results of antibody tests. While that might seem like science fiction, scientists feel we are now “entering into a new world.” One could imagine this being applied primarily to everybody who might need to be in the workforce or might need to go to school. People who are positive can potentially go forth and do critical jobs that involve exposure, and they would be at no risk, or much-reduced risk, compared to people who are negative.