A study out of the Harvard School of Public Health in april noted some strains were harder to locate out of a rapid test than others. The Delta Variant was more difficult to detect. It had a higher detection than omicron. And so this may relate to the omicron subvariants because some of the strains of the omicron subvariant do have mutations. Reporter dr. Kirby says like vaccines are getting new strain updates, so should tests. If we look at a lot of the antigen tests out there, they just have information in terms of how well they work for sort of original reporter its a sentiment echoed by a doctor of uc berkeley. We have to be constantly relooking at the rapid tests to make sure this virus spins off new variants and subvariants. Reporter dont be surprised if the rapid test comes up negative when you have symptoms. Oftentimes, early in the course of the illness the rapid test is negative when you actually have that disease. Reporter do what karl and his wife did. We knew that we were