CD4 and infection: Concurrent infection of mice with influenza virus and BCG (challenge on day 0) and sequential infection of mice with TB and influenza virus (TB infection on day 0 and influenza virus 7 weeks later) compared to infection with BCG only resulted in reduction in BCG‐specific CD4 and CD8 T‐cell responses, increased pulmonary disease and a delay in mycobacterium clearance from the lungs of infected mice.