Charles Corfield, nVoq’s CEO, is back with his latest thoughts on antibody testing during the COVID-19 pandemic. Please check back weekly to read more of Charles’ thoughts.
On the pandemic front, the uptick in cases in various sunbelt states has been making the headlines. However, circumstances have changed since March/April. The testing capacity is higher, which means that people who could not get tested three months ago, would be able to now. So the uptick in numbers is, in part, a result of increased testing availability, and that is also supported by the decrease in average age of people testing positive. The more germane issue is to keep the hospitalization rate within the capacity of the hospitals.
As antibody tests become more widely available, let me clarify a few items which have been lost in the glare of publicity. A positive result from an antibody test means you have been exposed to sars-cov-2 (sliding over the small error rate in approved tests), but a negative result does not mean that you have not had covid-19 (apologies for a double negative). A good chunk of people who have been exposed to sars-cov-2 will not have detectable antibodies, but they would probably test positive by a type of test which measures whether T cells (strictly, PBMCs, or peripheral blood mononuclear cells) have been primed to recognize viral proteins. Currently, there are no widely available tests for this type of immunity. At risk of getting too far ahead of my ski tips, it is possible that if one person in a household has had symptomatic covid-19, we would find that most of the household will be either antibody positive or (antibody negative and) T cell positive. Those who had obvious symptoms are more likely to be antibody positive, and those with mild or no symptoms are more likely to be antibody negative and T cell positive.
The average household size in the US is 2.5 people, so it is easy to imagine doubling any of the figures we have heard about the number of people who have been infected. The lack of T cell tests means that we still have a large blind spot about the true rate of exposure and all the official figures are (likely) way below the real numbers. Fixing this data deficit in the coming months matters because good public health recommendations depend accurate data. There aren’t yet many published results of testing populations within the US for prevalence of antibodies, so let me share a number from Blaine County, Idaho, where a climbing/running buddy runs emergency services: antibody tests are running 23% positive. Blaine is a classic rural western county, the reason for its high incidence is that it hosts the Sun Valley ski resort and the virus came in via ski tourism.