The Centers for Disease Control and Prevention said Friday the number of measles cases in the United States has increased to 62 as of Thursday, higher than the whole of last year.

The CDC issued a health advisory on Monday urging people, particularly children and international travelers, to get vaccinated against measles due to the increase in cases this year. Total cases were at 58 last week.

Most cases reported this year have been among children aged 12 months and older who had not received the measles-mumps-rubella (MMR) vaccine.

The World Health Organization issued a global warning on Tuesday pointing to "big gaps" in immunization programs putting more than half of the world's countries at high or very high risk of measles outbreaks by the end of the year.

Measles is a highly contagious, airborne virus that mostly affects children under the age of 5. It can be prevented by two doses of vaccine and more than 50 million deaths have been averted since 2000, according to the WHO.