SAN ANTONIO As the chair of the UTSA Department of Mathematics who develops infectious disease models, Dr. Juan Gutierrez warns against pursuing a fools errand to achieve herd immunity, especially without a proven COVID-19 vaccine. Until that happens, there is no herd immunity, Gutierrez said. There is no herd immunity for this disease without an exceedingly high human cost.If COVID-19 does run amok infecting more people, Gutierrez said, theres no guarantee it would lead to widespread immunity. It certainly didnt in Sweden, where the smaller country now has a higher COVID-19 death rate than in the U.S, Gutierrez said. Download it today for more exclusive content.