Republican Sen. Rand Paul said he will not get his COVID-19 vaccine because he had already contracted COVID-19 earlier, adding that he believes he now has a "natural immunity."

Paul was one of the senators who tested positive for COVID-19 last March. He told on his WABC 770 AM interview that it is his personal decision to opt-out of getting the vaccine, according to a Fox News report.

The Republican senator said that unless there is evidence that the vaccine is more effective than having survived the virus, he will not be getting his dose of vaccine.

Paul said that getting the vaccine should be a personal choice. The senator was known to have a tirade with the nation's top infectious disease expert, Dr. Anthony Fauci, at Senate hearings for mask-wearing and the origin of the virus.

Meanwhile, the Centers for Disease Control and Prevention has encouraged people who have had COVID to get a vaccine as experts are not certain how long an individual is protected against COVID-19 after recovering.

The CDC said that it is possible to be infected once again after being infected with the virus, although the chances are slim, according to a New York Post report.

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Paul Clashes With Fauci

Paul had attacked Fauci last November, telling the infectious disease expert that he "tends to gloss over the science."

This changed when Senate Minority Leader Mitch McConnell has supported Fauci and publicly encouraged Americans to take the vaccine, according to a Business Insider report.

Paul had said one time that people who had contracted COVID-19 and recovered did not need to wear masks.

He added that people should be told to scrap the masks and go to restaurants and live again, as they are already immune.

COVID-19 Vaccine in The U.S.

The CDC had reported that 61.1 percent of adults have already received at least one vaccination dose, while 49.1 percent of the adult population is already fully vaccinated.

Weeks ago, the U.S. had started using the vaccine from Pfizer-BioNTech to vaccinate young adolescents against COVID-19.

The U.S. Food and Drug Administration on Monday had authorized the vaccine for children 12 to 15, according to a Reuters report.

During the trial evidence, it showed that no one in the age group who received the vaccine got infected with COVID-19. In addition, there were no severe allergic reactions.

CDC Director Rochelle Walensky said the move will allow vaccination to about 17 million adolescents, adding that the agency officially recommends the vaccine.

Fauci said that the variants are all the more reason to get vaccinated.

Major vaccines such as Pfizer-BioNTech, Moderna, Johnson & Johnson, Sputnik, and AstraZeneca had shown promising effectiveness against the British variant, also known as B.1.1.7.

Clinical trial data from J&J and AstraZeneca also showed that they are highly effective against both preventing infection and serious illness in areas where B.1.1.7 is widespread.

Currently, the South African and Brazilian variants are causing the most concern, according to The New York Times report.

The two variants were reported to be better at curbing the vaccine antibodies as compared to other variants.

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WATCH: Rand Paul Says He's Refusing Vaccination Because He Already Had COVID - from News Today