Frequently Asked Questions
Does having anti-SARS-CoV-2 antibodies provide protection from getting the disease again?
Can a person with anti-SARS-CoV-2 antibodies still spread the virus?
No, it does not seem that those who have elevated IgG anti-SARS-CoV-2 antibodies can easily spread the virus, as studies show an inverse level of viral shedding with the occurrence of an antibody immune response. Since antibodies persist for several months after infection, it would not be useful to continue PCR testing these individuals as long as they continue to have a positive antibody response.
Is PCR testing (the nose swab COVID19 test) still useful after a person has had a known infection with an antibody response?
Do we know what a serology response for an effectively vaccinated person looks like in comparison to a previously infected SARS-CoV-2 person?
This is currently unclear, however, as soon as a vaccine is available to the wider community (aside from only in trials), we will be able to compare our sample of previously infected patients’ serum to vaccinated patients’ serum. This will depend on the mechanism of action of the vaccine as well since the antibody response is not the only immune system action responsible for immunity
Are certain anti-SARS-CoV-2 antibodies more effective at predicting immunity than others?
Yes, it seems that antibodies to SARS-CoV-2 virus, specifically attaching to the Spike S1 protein and RBD (receptor binding domain) are the most specific to SARS-CoV-2 (as compared to the other benign coronaviruses) and have the best correlation with neutralizing the virus.
If I have anti-SARS-CoV-2 antibodies, does that mean my family would have the same antibodies and be protected from SARS-CoV-2 infection?
Just because people are infected with the same exact strain of SARS-CoV-2 does not mean their antibody response will be exactly alike. Everyone produces an individual antibody pattern depending on your genetic background. However, current antibody detection tests can’t detect minor differences in the types of antibodies produced and the exact binding sequence of those antibodies. Differences between patients infected with the same strain of virus are typically enumerated by the amount of antibodies produced. For example, children, mildly symptomatic/asymptomatic adults, and severely symptomatic adults have different antibody profiles.
How long do anti-SARS-CoV-2 antibodies last?
If I tested PCR positive for SARS-CoV-2, but was asymptomatic, does this have any effect on my level of antibodies?
While I have antibodies for SARS-CoV-2, should I still receive a vaccine?
There is currently not enough information available to answer this question. Until a vaccine is available in order to compare natural immunity to vaccine induced immunity, a vaccine will need to be widely available and administered. The Advisory Committee on Immunization Practices will make a recommendation to the CDC who in turn will advise the public once enough information is available. It is however likely unnecessary to receive a vaccine as long as you continue to have an overall positive result on an antibody test with reactive IgG antibodies.
What benefit is there for companies/communities to test their people for anti-SARS-CoV-2 antibodies?
If a person already has an antibody response to SARS-CoV-2, then repeat PCR testing would not be useful until the antibody response has been depleted (typically >6 months). If your organization/community is doing periodic PCR testing, those who have a positive antibody test could stop getting PCR testing and instead repeat antibody testing every few months to see when their antibody response becomes undetectable. Once an antibody response depletes, it may be useful to get either a vaccine or resume periodic PCR testing for that individual.
References: PMID: 32945214
Do I need to do the antibody test once, or should I get tested regularly?
Various studies have demonstrated that COVID19 antibodies remain in your body for some time after the infection. If your antibody test result is positive, we suggest that you get tested every 2-3 months to assure your antibody level has not depleted substantially. If your antibody test was negative and you have not had symptoms or known exposures, retesting is likely not useful as far fewer asymptomatic individuals produce a meaningful antibody response
References: PMID: 32945214
If a test is negative, but a low level of reactivity to SARS-CoV-2 is present, are those antibodies protective?
While presently unknown, it seems that antibodies that are not specific to SARS-CoV-2, but rather cross-reactive, do not protect you from contracting the SARS-CoV-2 virus. However, it is unclear if the cross-reactive antibodies make the disease milder or of shorter duration, as is seen with cross-reactive antibodies for influenza strains