Over 95% of adults have been infected and are immune to HHV-7, and over three quarters of those were infected before the age of six. Primary infection of HHV-7 among children generally occurs between the ages of 2 and 5, which means it occurs after primary infection of HHV-6. A 2014 Washington University School of Medicine's analysis of 102 healthy adults sampled at as many as five major body habitats found that HHV-7 was present in 98% of them, especially in the mouth. A 2017 study looking at the human blood virome in 8,240 humans between the ages of 2 months to 102 years found that 20.37% of them were positive for HHV-7.
Human betaherpesvirus 7
Human betaherpesvirus 5
Human herpesvirus 6
Trichodysplasia spinulosa polyomavirus
Human T-lymphotropic virus
Human T-lymphotropic virus 1
Human T-lymphotropic virus 2
Yaba monkey tumor virus