Hong Kong’s health department is investigating at least one private clinic over the alleged use of HPV (human papillomavirus) vaccines from unknown sources, after the sole manufacturer denied providing products to it.The investigation was launched as manufacturer MSD paid for front-page ads in local newspapers on Friday reminding customers not to use “Gardasil 9” vaccines that did not carry its local registration details on the packaging. A lawmaker also reported to the department that she had…