Measles is spread through contact with an infected person’s mucus or saliva which can happen when an individual coughs/sneezes without covering their mouth; additionally, it can also be passed on by sharing eating utensils or other objects that have come into contact with someone who is contaminated.
Quarantine and isolation are effective control measures when immunization isn’t an option because they help limit the spread of the virus. For example, if someone comes into contact with a contagious virus like measles but doesn’t yet have symptoms then placing them under quarantine for 14 days will greatly reduce their chance of infecting anyone else even if they become ill during that period. Separating a sick person from others will stop any transmission.
The methods described above are effective in preventing potentially devastating outbreaks. But, there could also be factors like access to health care that can impact the effectiveness of these measures.