DES MOINES — As Iowa officials work to speed up inoculations in hopes of halting the COVID-19 pandemic, a lawmaker Tuesday subjected one of the state’s top health experts to a series of questions skeptical of vaccinations.The encounter came during a hearing on a bill that would, among other provisions, bar Iowa businesses including hospitals and other health care providers from requiring their employees to get any vaccine, or using people’s vaccination history to determine employment.Legislative hearings typically feature rapid-fire comments from dozens of organizations and individuals who are interested in a bill.