Travelers in at Least 5 U.S. Airports Were Exposed to Measles in December

There is no scientific link between vaccines and autism, according to the Centers for Disease Control.

Countless flyers may have been exposed to measles after individuals with the highly infectious virus entered at least five airports around the country this month, according to officials.

The Chicago Department of Public Health reported a passenger with measles entering Chicago’s O’Hare International Airport twice in less than a week in mid-December. The unidentified traveler first entered the airport through Terminal 3 on December 12, then reentered through Terminal 1 five days later. Chicago has some of the highest rates of measles, mumps and rubella vaccination in the U.S., ABC News noted.

Another traveler with the virus entered Richmond International Airport in Virginia on December 17. That same day, another infectious passenger entered the United Airlines gate area at Austin-Bergstrom International Airport, according to Austin Public Health.

“Measles is an acute, highly contagious viral disease. A small number of cases are capable of quickly producing epidemics,” Dr. Mark Escott, interim health authority and medical director at Austin Public Health, said in their statement. “The best way to protect yourself and your family against measles and other vaccine-preventable diseases is by immunization.”

According to the CDC, it takes between seven and 14 days for signs of measles to first appear. These symptoms can manifest as a cold, high fever, runny nose and watery eyes. Just days after these symptoms begin, tiny white spots may become visible inside the infected person’s mouth, followed by a rash — marked by small raised bumps — appearing on their face and body.

RELATED: Measles Outbreak the Worst in Over 25 Years with Nearly 1,000 Cases in the U.S.

In early December, three unvaccinated children visited two U.S. airports after they returned home from a country with an ongoing measles outbreak.

On December 11, the children traveled through multiple areas of Denver International Airport, including the baggage and pickup area in Concourse A, Fox News reported.

They also traveled through Terminals 4 and 5 of Los Angeles International Airport during their trip home, the Los Angeles Department of Public Health said.

As PEOPLE previously reported, some parents are choosing for themselves or their children to go unvaccinated, despite extensive research proving the safety of the vaccine. This is partially due to the spread of misinformation about the vaccine, which has led parents to opt-out of giving children the life-saving protections.

RELATED VIDEO: Michigan Mom Is Jailed for 7 Days After Refusing to Vaccinate 9-Year-Old Son

Cases of the measles worldwide are up by 300 percent in the first three months of 2019, compared to the same time period last year, based on preliminary data, the World Health Organization says.

While there are continued outbreaks in countries with low vaccination rates —the Democratic Republic of the Congo, Ethiopia, Georgia, Kazakhstan, Kyrgyzstan, Madagascar, Myanmar, Philippines, Sudan, Thailand and Ukraine — they are also occurring in countries where the disease was thought to be eradicated, thanks to the measles vaccine.