Federal health officials have identified more measles cases, bringing the total nationwide number to 101.
So far, the Centers for Disease Control and Prevention (CDC) says there are confirmed cases in 10 US states since January 1.
The first measles vaccine was introduced in 1963 and, by 2000, it was considered to be eradicated in the US.
But the highly infectious disease has been spreading among people who are unvaccinated or live in states that allow non-medical exemptions for vaccines.
Doctors say these states, have become 'hotspots' of the anti-vaccine movement and that the only way to curb the crisis is to ban non-medical exemptions completely.
As of January 1, the Centers for Disease Control and Prevention has identified 101 confirmed cases in California, Colorado, Connecticut, Georgia, Illinois, New Jersey, New York, Oregon, Texas and Washington
Cases have been confirmed in California, Colorado, Connecticut, Georgia, Illinois, New Jersey, New York, Oregon, Texas and Washington.
Of those states, four - Colorado, Oregon, Texas and Washington - allow exemptions for philosophical and/or personal beliefs.
Washington and New York, particularly, have been struggling to contain the disease that was considered eliminated 20 years in ago.
Last month, Washington declared a public health emergency after a measles outbreak that has affected 53 people in Clark County.
STATES THAT RECENTLY REVOKED THIS ALLOWANCE:Vermont California Missouri West Virginia
Forty-seven of the cases are in residents who have not been vaccinated. Thirty-eight cases are in children aged 10 and under.
State records show that 77.4 percent of all public students in Clark County received all their vaccines, making it among the worst in Washington state, according to The Oregonian.
Meanwhile, for the 2017-18 kindergarten school year, the median vaccination rates nationwide were 95.1 percent for DTaP, 94.3 percent for the MMR vaccine and 93.8 percent the chicken pox vaccine, the CDC reported.
In Washington, nearly eight percent of children in the county were exempt from getting vaccines required for kindergarten for the 2017-18 school year.
A mere 1.2 percent were for medical reasons, while the rest were for 'conscientious objector' or 'philosophical/personal