Indoor masking required for all at Western Michigan University as of Wednesday By Will Kriss Aug 4, 2021 | 4:04 PM KALAMAZOO, MI (WKZO AM/FM) â Wednesday, officials with Western Michigan University (WMU) announced that masking when indoors will now be required, effective immediately. In a news release to the WMU community, medical officials explained that the decision is due to the ongoing spread of the Delta variant of COVID-19. Kalamazoo County was recently determined as an area with âsubstantialâ transmission by the CDC. People living in areas deemed to have âsubstantialâ or âhighâ transmission are advised to wear masks indoors, even if fully vaccinated.