A nurse injects a modena vaccine at a hospital in Connecticut.

The U.S. will start the third vaccination of a new coronavirus infection (COVID-19) vaccine against its citizens from the 20th of next month.

According to Reuters on the 18th, U.S. health officials announced in a joint statement that they would give booster shots to Americans who had been vaccinated with up to two rounds of Pfizer or Moder or vaccine.

Americans who have been vaccinated with Pfizer, Moder or Vaccine must be given a booster shot eight months after receiving the second vaccination. The first targets of vaccination are medical workers who received vaccination within the end of last year and elderly people who entered nursing homes early this year.

"It is clear from the known data that the prevention function for coronavirus (vaccine) begins to decline over time," officials said. "There is also evidence that the spread of delta mutations also decreases immunity to mild or moderate symptoms."

He also stressed, "We decided that booster shots would be needed to maximize the induced immune effect of the vaccine and extend its persistence."

They said they also expect booster shots from those who received the Jansen vaccine, a one-time vaccine, and added that they will announce the plan later.

The joint statement was under the names of Rochelle Wallensky, director of the CDC, Janet Woodcock, acting director of the Food and Drug Administration (FDA), and Anthony Pouch, director of the National Allergy and Epidemics Institute (NIAID).

So far, advanced countries such as Israel, France and Germany have decided to take booster shots against their citizens. They decided to provide booster shots to the elderly as well as the immune system vulnerable.