The critical difference is that older patients and those who are immune-compromised tend to lack a robust T-cell response, which Heat Biologics believes is important in preventing the disease. With the typical flu, seniors are often prescribed a double-dose of vaccine to compensate for their inability to mount an effective adaptive response. This approach, however, may not be optimal in vaccinating against COVID-19. New data suggests that a combination of T-cell and antibody responses against COVID-19 may provide the best protection for seniors and others.