Every newborn should get immunized against hepatitis B virus (HBV) within 24 hours of birth, according to new, more rigorous recommendations from the U.S. Centers for Disease Control and Prevention (CDC). The update is likely to push hospitals across the country to institute an opt-out approach toward parental approval for the shot, rather than the current opt-in protocol, Philly.com reports.

While some parents may want the hepatitis B vaccine done by their doctor in the office, or not want it at all, federal authorities are strongly urging no delay. In the report, the CDC’s Advisory Committee on Immunization Practices (ACIP) noted that hepatitis B is easily transmitted through blood and bodily fluids (including saliva, tears and urine). For many babies, this translates into a potential HBV risk via contact from doting loved ones who may have the infection without knowing it.

According to the CDC, as many as 2.2 million people in the United States may be infected with hepatitis B, and most don’t know it. Since the hepatitis B vaccine didn’t become commercially available in the United States until 1982, adults and seniors are the most likely to be living with an undiagnosed infection. The virus is also more common among U.S. immigrants from Asia and Africa, where vaccinations have not been routine.

The ACIP’s report also announced some changes for the human papillomavirus (HPV), Tdap (tetanus, diphtheria, pertussis) and meningitis B vaccines—most notably that young teens who get the HPV shot before age 15 need only two doses, at least six months apart, rather than the previously recommended three.

To read more about the CDC’s updated recommendations, click here.