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It has been said that there is some likelihood that exposure to a previous Coronavirus made some people partially resistant to Covid-19. Would that mean that th

It has been said that there is some likelihood that exposure to a previous Coronavirus made some people partially resistant to Covid-19. Would that mean that there is a chance that some people test positive for Covid-19 antibodies due to a different strain of Coronavirus?

zatertip 6y ago
IIRC, no samples from before December 2019 tested positive for SARS-COV-2 antibodies in the papers I’ve read.
shireboy 6y ago
From CDC on antibody tests: A positive test result shows you may have antibodies from an infection with the virus that causes COVID-19. However, there is a chance a positive result means that you have antibodies from an infection with a virus from the same family of viruses (called coronaviruses), such as the one that causes the common cold. https://www.cdc.gov/coronavirus/2019-ncov/testing/serology-overview.html https://www.cdc.gov/coronavirus/2019-ncov/testing/serology-o... I have not read enough on this specific NYC testing to know for sure if they control for that somehow, or if controlling for it is even possible. Seems like it would be a factor, though.
ageitgey 6y ago
You are probably talking about how previous coronavirus exposure seems to give some people some level of T-cell protection against SARS-CoV-2. T-cells are a different part of the immune system from immunoglobulin proteins, which is what these antibody tests measure. So it's more likely that those people would show up as a negative on this test because they wouldn't have the right immunoglobulins in their blood. It's also possible that some people are fighting off COVID via a T-Cell response while not developing significant immunoglobulins or that immunoglobulin levels fade quickly while T-Cells don't. Those people can also test negative for immunoglobulin antibodies despite fighting off the disease. So it's actually more likely that these tests are significantly under counting exposed people in total. But these tests aren't perfect and for any specific person, they could give you a false positive or a false negative result.
UncleOxidant 6y ago
I don't think so. Antibodies are pretty specific. However it's possible and there is some data to suggest that some people have T-Cell level immunity to SARS-Cov-2 that was likely induced by exposure to an earlier coronavirus.
- mr_toad 6y ago
  > Antibodies are pretty specific. Not always. Famously, cowpox antibodies protect against smallpox.

zatertip 6y ago

IIRC, no samples from before December 2019 tested positive for SARS-COV-2 antibodies in the papers I’ve read.

shireboy 6y ago

From CDC on antibody tests: A positive test result shows you may have antibodies from an infection with the virus that causes COVID-19. However, there is a chance a positive result means that you have antibodies from an infection with a virus from the same family of viruses (called coronaviruses), such as the one that causes the common cold. https://www.cdc.gov/coronavirus/2019-ncov/testing/serology-overview.html https://www.cdc.gov/coronavirus/2019-ncov/testing/serology-o... I have not read enough on this specific NYC testing to know for sure if they control for that somehow, or if controlling for it is even possible. Seems like it would be a factor, though.

ageitgey 6y ago

You are probably talking about how previous coronavirus exposure seems to give some people some level of T-cell protection against SARS-CoV-2. T-cells are a different part of the immune system from immunoglobulin proteins, which is what these antibody tests measure. So it's more likely that those people would show up as a negative on this test because they wouldn't have the right immunoglobulins in their blood. It's also possible that some people are fighting off COVID via a T-Cell response while not developing significant immunoglobulins or that immunoglobulin levels fade quickly while T-Cells don't. Those people can also test negative for immunoglobulin antibodies despite fighting off the disease. So it's actually more likely that these tests are significantly under counting exposed people in total. But these tests aren't perfect and for any specific person, they could give you a false positive or a false negative result.

UncleOxidant 6y ago

I don't think so. Antibodies are pretty specific. However it's possible and there is some data to suggest that some people have T-Cell level immunity to SARS-Cov-2 that was likely induced by exposure to an earlier coronavirus.

mr_toad 6y ago
> Antibodies are pretty specific. Not always. Famously, cowpox antibodies protect against smallpox.