D.C. health officials have issued a warning that attendees of the recent March for Life rally may have been exposed to measles. Multiple confirmed cases of the virus have been reported in the district, with potential exposures noted at various events and public locations, including Reagan National Airport and the national shrine. Health officials are urging individuals who attended the rally to monitor symptoms and ensure their vaccinations are up to date. The situation has raised concerns about the rally being a possible superspreader event for the measles virus during this outbreak.