Abstract: Methods, formulations, and uses of a prophylactic nasal spray are provided. Many embodiments include nasal spray formulations including an microbicidal (e.g., virucidal) agent. Various embodiments include iodine, such as povidone iodine (PVP-I) as the microbicidal agent. Additional embodiments include methods to prophylactically treat an individual to prevent, mitigate, or otherwise limit a microbial infection.