Young teens who get the human papillomavirus vaccine before turning 15 need only two doses, rather than three, recommended the Centers for Disease Control and Prevention last week.

The CDC's Advisory Committee on Immunization Practices also announced some changes for the Hepatitis B, Tdap (Tetanus, Diphtheria, Pertussis), and Meningitis B vaccines. These changes will be official when reviewed by the director of the CDC and published in their weekly newsletter, the MMWR, but there is no reason to think the recommendations will be modified. Here's what you need to know about these updated recommendations:

1. The latest HPV vaccine prevents infection from nine strains of human papilloma virus which cause venereal warts, but the infection may not be apparent without lab testing. These viruses are very easily transmitted and it is estimated that 90 percent of people in the United States who are not immunized will acquire one or more HPV strains within 18 months of initiation of intimate contact (the disease can be acquire just from the touching of mucous membranes together, not just intercourse.)

Acquiring HPV may lead to cervical dysplasia and cervical dysplasia can lead to cervical cancer. HPV is the only cause of cervical cancer and the most common cause of rectal, penile and oral cancer currently in the US. Over 4,000 woman in the US die yearly from HPV caused cervical cancer and twice as many men and women die yearly from all the HPV caused cancers.  Initially, a four strain vaccine was introduced and a nine strain vaccine has been available for the last four years.

In spite of problems with vaccine refusal so that less than half of young women (42 percent) are fully vaccinated, the rate of cervical dysplasia is falling in younger woman when the rate of all other sexually transmitted diseases has sky-rocketed. For example, syphilis which was almost eliminated from the US 10 years ago has gone up 25 percent from 2014 to 2015, and gonorrhea and chlamydia have also increased markedly. So the effectiveness of the vaccine has been a great success.

Although three doses are still needed in those over 15 who are incompletely vaccinated, the new rules state that just two doses of nine strain HPV vaccine at least six months apart will fully vaccinate younger (less than 15 years old) teenagers. Remember both boys and girls need the vaccine which can be given as young as age 9, but is usually started at age 11.

2. Hepatitis B vaccine is offered to every newborn in the hospital at birth in the US.  Some parents want it done by their doctor in the office or do not want it at all, but the ACIP strongly recommended no delay. It is easily transmitted through either blood or body fluid (saliva, tears, urine) contact from an adult with the disease and some adults may not know they are infected. This recommendation of every newborn getting an immunization for Hepatitis B within 24 hours of birth is much more rigorous than then before and hospitals will probably go to an "opt-out" approach (the parent must sign to have the baby not get the immunization) than the "opt-in" (the parent must sign for the baby to get the immunization).

3. The ACIP continues to recommend that every pregnant woman get Tdap­ (tetanus, diphtheria and Pertussis/whooping cough vaccine) at 27 weeks of her gestation and no later than 36 weeks to protect herself and her child against whooping cough, which is potentially fatal in a newborn and frequently carried by young adults.

4. The Meningitis B vaccine (MenB) is available in two different products and is not required.  It is recommended if the patient is at least 10-years-old and has immune suppression such as no spleen, has a complement deficiency, or is in close contact with someone with Meningitis B.  In these cases, the patient needs three doses two of which must be at least six months apart.

Young people 16 to 23-years-old can also elect to have this immunization without high-risk and then may have only two doses of the Trumenba brand vaccine at least six months apart.

Have a question for the Healthy Kids panel? Ask it here. Read more from the Healthy Kids blog »