COVID-19 Antibody Testing – An Update and Pitfalls

1. COVID-19 ANTIBODY TESTING AN UPDATE AND PITFALLS Covid19antibody testing has been a much talked about the topic recently. Broadly speaking there are instant-result home testing and laboratory tests – both use different methods.Regarding the point of care/home testing, most manufacturers report >95% accuracy, however, there was hesitation about them being widely rolled out. This comes down to 2 main reasons; False negatives – most tests have been validated on known COVID-19 patients that have been admitted to the hospital. By default, these patients will be quite unwell and have likely mounted a strong immune response so antibodies will be more easily detected.

2. False positives – there are other coronaviruses that have been circulating seasonally for many years – often causing mild cold / flu-like symptoms. We are unsure whether these home testing kits are specific enough. So an individual may test positive if they have been infected with a coronavirus that is not SARS-CoV-2, this is obviously a concern and can lead to individuals/families/companies making unwise decisions based on the assumption that they are immune. New Laboratory testing using methods such as ELISA is more promising. They can provide quantitive antibody levels, rather than a negative or positive reading, so are able to identify those patients that had mild symptoms with lower antibody levels in the community. The body produces different antibodies to different parts of the SARS-CoV-2 virus. Some antibody responses are stronger than others. The better tests now look for more than 1 antibody which also increases sensitivity. Also, many of the lab-based tests report better no cross-reactivity to other coronaviruses which increases specificity, this should mean fewer false positives. In fact, the latest laboratory-based antibody tests have sensitivity and specificity values of over 99%. The big question however remains, what does a positive antibody result mean? Does it guarantee protection from COVID19 or a less severe infection in the future – hopefully, yes, but unfortunately we don’t yet know for sure. Contact Us thegpclinondon.com info@thegpcliniclondon.com