President Donald Trump on Friday urged parents to get their children vaccinated after the Centers for Disease Control and Prevention announced this week that measles cases had reached a record high since the disease was declared eliminated in 2000.
"They have to get the shot. The vaccinations are so important," Trump said outside the White House on his way to Indianapolis to address the NRA. "This is really going around now, they have to get their shot."
Nearly 300 students and employees at two Los Angeles universities were under quarantine Thursday and Friday after possible exposure to measles.
Trump's comments on Friday differed from his past remarks on vaccinations.
At a 2015 Republican presidential candidate debate hosted by CNN, Trump said that he wanted to change the vaccine schedule for children, erroneously linking autism to vaccines.
RELATED: Treatment, preventative care and vaccinations for measles around the world
Treatment, preventative care and vaccinations for measles across the world
Treatment, preventative care and vaccinations for measles across the world
A child receives a vaccination against measles by a family physician on April 16, 2018 in the Romanian capital, Bucharest.
Measles still claims young lives in Romania, where nearly 40 children have died in an outbreak that many blame on parents being misled by scare stories that vaccinating them is dangerous. Some 12,000 people have contracted measles since late 2016 in the European Union's second-poorest country, 46 of them died. Among the dead, 39 were children under the age of three who had not been vaccinated, making Romania one of the worst affected countries in the ongoing measles outbreak in Europe. / AFP PHOTO / Daniel MIHAILESCU (Photo credit should read DANIEL MIHAILESCU/AFP/Getty Images)
A family physician prepares a measles vaccine during a consultation on April 16, 2018 in the Romanian capital, Bucharest. - Measles still claims young lives in Romania, where nearly 40 children have died in an outbreak that many blame on parents being misled by scare stories that vaccinating them is dangerous. Some 12,000 people have contracted measles since late 2016 in the European Union's second-poorest country, 46 of them died. Among the dead, 39 were children under the age of three who had not been vaccinated, making Romania one of the worst affected countries in the ongoing measles outbreak in Europe. (Photo by Daniel MIHAILESCU / AFP) (Photo credit should read DANIEL MIHAILESCU/AFP/Getty Images)
A nurse was seen vaccinating school children at her school in Lhokseumawe, August 4, 2018, Aceh, Indonesia. Vaccination Measles-Rubella (MR) for Indonesian school children is part of the Indonesian government's health program to provide physical immunity from two dangerous diseases, Rubella and Measles in Indonesian children. (Photo by Fachrul Reza/NurPhoto via Getty Images)
Artists wearing superhero costumes comfort an elementary student while she receives a German Measles, also known as Rubella, vaccination in Pekanbaru, Riau province on August 1, 2018 as part of the Indonesian governments health program to combat childhood diseases. (Photo by WAHYUDI / AFP) (Photo credit should read WAHYUDI/AFP/Getty Images)
ALEPPO, SYRIA - APRIL 17 : A Syrian child is vaccinated during the measles campaign in Al-Bab district of Aleppo, Syria on April 17, 2018. Kids fled from Eastern Ghouta's Douma after Assad regime forces' suspected chemical attack on April 7, 2018 receive measles vaccine Al-Bab district of Aleppo. (Photo by Omer Alven/Anadolu Agency/Getty Images)
A Venezuelan woman is vaccinated against measles in Cucuta, Colombia, at the international brigde Simon Bolivar on the border with Venezuela, on March 21, 2018. / AFP PHOTO / Schneyder Mendoza (Photo credit should read SCHNEYDER MENDOZA/AFP/Getty Images)
Venezuelan, Yan Manuel, receives a free measles vaccine given by a volunteer, after showing his identity card at the Pacaraima border control, Roraima State, Brazil August 19, 2018. REUTERS/Nacho Doce
A member of the Free Revolutionary Police carries out an inspection on a measles vaccine in the southern Idlib countryside September 17, 2014. Fifteen children died after being vaccinated against measles in northern Syria, resulting in the programme being halted, aid workers said on Wednesday, a tragedy likely to damage trust in health services in opposition-held areas. The Free Revolutionary Police is a newly launched unarmed police movement that works in areas controlled by the Free Syrian Army to solve the day-to-day problems in Idlib, the group said. Picture taken September 17, 2014. REUTERS/Khalil Ashawi (SYRIA - Tags: CIVIL UNREST CONFLICT HEALTH)
A girl receives anti-measles vaccination drops at a health centre in BASECO compound in Tondo, Manila September 3, 2014. Philippine President Benigno Aquino said on September 1, 2014 between 11 to 13 million people in the country are at risk from measles, polio and rubella (German measles), and asked the public to cooperate in eradicating the preventable diseases, during Monday's launch of a mass national vaccination campaign against measles and polio, reported local media. REUTERS/Erik De Castro (PHILIPPINES - Tags: HEALTH SOCIETY)
A vial of measles, mumps and rubella vaccine and an information sheet is seen at Boston Children's Hospital in Boston, Massachusetts February 26, 2015. REUTERS/Brian Snyder (UNITED STATES - Tags: HEALTH)
Rowan Walters, aged four, is held by her mother as she given an MMR injection at the Paediatric Outpatients department at Morriston Hospital in Swansea, south Wales April 6, 2013. Following an increase in the number of confirmed cases of a measles in south Wales, parents in the area were urged to vaccinate their children, and hospitals in the region opened drop-in clinics on Saturday, local media reported. REUTERS/Rebecca Naden (BRITAIN - Tags: SOCIETY HEALTH)
A health worker in Ciudad Juarez at the Mexican border crossing with El Paso, Texas, hands out leaflets to passing motorists and people as part of a measles prevention programme, February 16, 2015. California public health officials have confirmed three more cases of measles in an outbreak that began in late December, bringing to 113 the total number of people believed to have been infected in the state. Health officials in Arizona, where seven cases of measles have been documented, said the outbreak would likely be considered over in that state if no further infections were reported over the weekend. Across the United States, more than 150 people have been diagnosed with measles, many of them linked to an outbreak that authorities believe began when an infected person from out of the country visited Disneyland in late December. REUTERS/Jose Luis Gonzalez (MEXICO - Tags: SOCIETY HEALTH IMMIGRATION)
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"Autism has become an epidemic…I am totally in favor of vaccines. But I want smaller doses over a longer period of time," he said.
In a March 2014 tweet, Trump questioned why a child "gets pumped with massive shot of many vaccines."
"Healthy young child goes to doctor, gets pumped with massive shot of many vaccines, doesn't feel good and changes — AUTISM. Many such cases!" he tweeted.
There is no link between vaccines and autism, according to multiple studies, health care experts and the CDC. Since 2003, the CDC has also conducted or funded nine studies that show that vaccine ingredients, such as the mercury-based preservative thimerosal, do not cause autism.
The CDC has urged health care providers to assure patients that the vaccine is safe and effective, reiterating in a Thursday statement that "vaccination is the best way to protect against measles."
The reported measles cases were scattered across 22 states, an outbreak that CDC Director Robert Redfield called "deeply troubling” in a tweet.
"I encourage all Americans to adhere to CDC vaccine guidelines to protect themselves, their families, and their communities from #measles and other vaccine preventable diseases. We must work together as a Nation to eliminate this disease once and for all," he said Thursday.
I encourage all Americans to adhere to CDC vaccine guidelines to protect themselves, their families, and their communities from #measles and other vaccine preventable diseases. We must work together as a Nation to eliminate this disease once and for all. https://t.co/EljIiiBp5T
On Wednesday, New York City and suburban Rockland County confirmed an additional 37 measles cases, and California reported seven new cases. The second-highest number for measles cases in the U.S. was 667 in 2014, according to the CDC.
In New York City and Rockland County, there have been 590 cases since the measles outbreak began in October 2018. Los Angeles reported its first five cases on Monday.