The US Centers for Disease Control and Prevention just increased their recommendations for booster shots of the coronavirus vaccine.

All adults should get a booster shot (six months after the second dose of Pfizer or Moderna's vaccine and two months after the single dose Johnson & Johnson vaccine) they said on Monday evening.

"Today, CDC is strengthening its recommendation on booster doses for individuals who are 18 years and older," CDC Director Dr. Rochelle Walensky said in a statement.

Walensky and the CDC cite the Omicron variant of the virus as part of the reasons for their decision.

"The recent emergence of the Omicron variant (B.1.1.529) further emphasizes the importance of vaccination, boosters, and prevention efforts needed to protect against COVID-19," she added.

This marks the boldest words from the CDC regarding booster shots. In recent weeks they had only said that "anyone 18 or old was eligible to receive a booster shot."

It is not immediately clear if the Omicron variant is more transmissible than the Delta variant. It is also not clear if the vaccine's efficacy will be affected by the new strain.

In the meantime, the CDC is urging Americans to continue practicing safety measures as fears mount surrounding the virus.

"I strongly encourage the 47 million adults who are not yet vaccinated to get vaccinated as soon as possible and to vaccinate the children and teens in their families as well because strong immunity will likely prevent serious illness," Walensky said Monday evening.

In the meantime, officials continue to anticipate the arrival of the Omicron strain of the virus, but to date, no cases have been officially reported in the United States.

"I also want to encourage people to get a COVID-19 test if they are sick. Increased testing will help us identify Omicron quickly," Walensky says. 

Answers to 25 common COVID-19 vaccine questions

Vaccinations for COVID-19 began being administered in the U.S. on Dec. 14, 2020. The quick rollout came a little more than a year after the virus was first identified in November 2019. The impressive speed with which vaccines were developed has also left a lot of people with a lot of questions. The questions range from the practical—how will I get vaccinated?—to the scientific—how do these vaccines even work?

Keep reading to discover answers to 25 common COVID-19 vaccine questions.