If nursing a patient with measles, there is a reason why gloves and hand hygine is still required. Medically, we consider the 97% effective as a population average besed upon “usual exposure”. That means 3 in 100 vaccinated children are likely to contract measles this way. If your. local exposure is higher, then there are higher infection rates in that peer group. If you sit next to me for 5 mins you have one risk of exposure. If we are kids in a classroom together for several hours, then the transmission risk is higher. So yes, just like COVID, the higher the proportion of infective people and the longer the contact time the greater the risk of infection and also transmission.