National Immunization Awareness Month

August is National Immunization Awareness Month and serves as an opportune time to review some of the current issues in the immunization field. Novel and pertinent developments include the threat of pandemic influenza, adolescent immunizations, a new vaccine for the elderly population, and the mumps outbreak in the Midwest.

Avian Influenza/Pandemic Influenza

Two subjects which have been in the forefront of the news this year are Pandemic and Avian influenza. Efforts at the federal, state, and local levels are focused on how to prepare for these public health threats. The County of San Diego Health and Human Services Agency continues to partner with other County, public, and private agencies to refine its efforts, which include year-round influenza surveillance; information sharing with the local medical community; and developing, testing, and refining a comprehensive response plan. A key component of these plans is public education. County HHSA has created a Pandemic Influenza information website, with information about avian flu and pandemic flu; local, state, and national response efforts; and links to a variety of other sources of information. The HHSA site is linked to a larger County bird/pandemic flu website, which also includes information from the Department of Environmental Health, the County Veterinarian’s Office, and the County Office of Emergency Services.
Adolescent Immunization

Adolescent Immunization: Human Papillomavirus Vaccine

There are a number of new or recent developments in immunization for adolescents. In June, the Food and Drug Administration (FDA) approved Gardasil® (Merck & Co., Inc.) for use in girls and women ages 9-26. This is the first vaccine developed to prevent cervical cancer, precancerous genital lesions, and genital warts due to human papillomavirus (HPV) types 6, 11, 16, and 18.

The Advisory Committee on Immunization Practices (ACIP) voted in late June to recommend that a newly licensed vaccine, designed to protect against human papillomavirus virus (HPV), be routinely given to girls when they are 11-12 years old. The ACIP recommendation also allows for vaccination of girls beginning at nine years old, as well as vaccination of girls and women 13-26 years old. HPV is the leading cause of cervical cancer in women.
According to the ACIP’s recommendation, three doses of the new vaccine should be routinely given to girls when they are 11 or 12 years old. The advisory committee, however, noted that the vaccination series can be started as early as nine years old at the discretion of the physician or health care provider. The recommendation also includes girls and women 13-26 years old because they will benefit from getting the vaccine. The vaccine should be administered before the onset of sexual activity (i.e., before women are exposed to the viruses), but females who are sexually active should still be vaccinated.

The Centers for Disease Control and Prevention (CDC) estimates that about 6.2 million Americans become infected with genital HPV each year and that over half of all sexually active men and women become infected at some time in their lives, making HPV the most common sexually transmitted disease (STD) in the U.S. There are an average of 9,710 new cases of cervical cancer and 3,700 deaths attributed to it in the United States each year. Worldwide, cervical cancer is the second most common cancer in women. In addition, HPV is estimated to cause over 470,000 new cases and 233,000 deaths each year.

For most women, the body's immune system will clear the virus and infected women do not develop related health problems. However, some HPV types can cause abnormal cells on the lining of the cervix that years later can turn into cancer. Other HPV types can cause genital warts. The vaccine is effective against HPV types 16 and 18, which cause approximately 70 percent of cervical cancers and against HPV types 6 and 11, which cause approximately 90 percent of genital warts.

Adolescent Immunization: Tetanus Toxoid Vaccines

In spring 2005, two tetanus toxoids, reduced diphtheria toxoid and acellular pertussis vaccine (Tdap) products [Adacel™ (sanofi pasteur) and Boostrix® (GlaxoSmithKline Biologicals)], were licensed in the United States for use in adolescents (and, for one product, Adacel™, use in adults). The pertussis antigen composition of the adolescent and adult Tdap formulations is similar to pediatric DTaP, but some or all of the pertussis antigens are reduced in quantity. The tetanus and diphtheria toxoid composition of Tdap is similar to licensed adult formulations of Td. Early in 2006, the ACIP released new recommendations for the use of the Tdap among adolescents aged 11-18 years, including replacing Td with Tdap as the 11 to 12-year-old booster dose.

In summary, to reduce pertussis morbidity in adolescents and maintain the standard of care for tetanus and diphtheria protection, the ACIP recommends that:

1. Adolescents aged 11–18 years should receive a single dose of Tdap instead of tetanus and diphtheria toxoids vaccine (Td) for booster immunization against tetanus, diphtheria, and pertussis if they have completed the recommended childhood diphtheria and tetanus toxoids and whole cell pertussis vaccine (DTP)/diphtheria and tetanus toxoids and acellular pertussis vaccine (DTaP) vaccination series (usually five doses of pediatric DTP/DTaP before the seventh birthday) and have not received Td or Tdap. The preferred age for Tdap vaccination is 11–12 years.
2. Adolescents aged 11–18 years who received Td, but not Tdap, are encouraged to receive a single dose of Tdap to provide protection against pertussis if they have completed the recommended childhood DTP/DTaP vaccination series. An interval of at least 5 years between Td and Tdap is encouraged to reduce the risk for local and systemic reactions after Tdap vaccination. However, an interval less than 5 years between Td and Tdap can be used.
3. Vaccine providers should administer Tdap and tetravalent meningococcal conjugate vaccine (Menactra®, sanofi pasteur, Swiftwater, Pennsylvania) to adolescents aged 11–18 years during the same visit if both vaccines are indicated and available.

New Herpes Zoster Vaccine

On May 30, 2006, the FDA licensed Zostavax® (Merck & Co., Inc.) vaccine for use in persons aged 60 years or older. The vaccine is intended to reduce the risk of herpes zoster (shingles). Zostavax® was studied in approximately 38,000 individuals, 60 years of age and older, with half receiving the vaccine and the other half receiving a placebo. After follow-up of participants, for an average of three years, the vaccine was found to reduce the occurrence of shingles by about 50%. The vaccine effect was highest for those 60-69 years of age, with a reduction by 64%.

Herpes zoster is estimated to affect 2 in every 10 people during their lifetime. Annually, it is estimated that one million or more cases of shingles occur in the United States. At press time, ACIP was formulating recommendations for use of this vaccine.

Mumps Outbreak in Midwest

As of June 6, 2006, 4,400 cases of mumps had been reported by 11 states. The outbreak in Iowa and surrounding states and previous evidence on mumps vaccine effectiveness and transmission resulted in ACIP updating recommendations for mumps vaccination. These recommendations included changes to acceptable presumptive evidence of mumps immunity, routine mumps vaccinations for health care workers, and expanded use of mumps vaccine in outbreak settings.

The recommendations are summarized below:

Acceptable Presumptive Evidence of Immunity:

• Documentation of adequate vaccination is now two (2) doses of a live mumps virus vaccine instead of one (1) dose for:
  
  • School-aged children (i.e., grades K–12).
  • Adults at high risk (i.e., persons who work in healthcare facilities, international travelers, and students at post–high school educational institutions).

Routine Vaccination for Healthcare Workers:

• Persons born during or after 1957 without other evidence of immunity: consider two (2) doses of a live mumps virus vaccine.
• Persons born before 1957 without other evidence of immunity: consider recommending one (1) dose of a live mumps virus vaccine.

For Outbreak Settings:

• Children aged 1–4 years and adults at low risk: if affected by the outbreak, consider a second dose* of live mumps virus vaccine.
• Healthcare workers born before 1957 without other evidence of immunity: strongly consider recommending 2 doses of live mumps virus vaccine.

*Minimum interval between doses = 28 days.

While there have been no confirmed cases of mumps in the County of San Diego, it is important for health care providers, especially those working in college and university student health centers, to be aware of current mumps vaccination recommendations to help prevent a potential outbreak in San Diego.

Much more information about vaccines and vaccine-preventable diseases is available from the San Diego County Immunization Initiative. Please visit the website at www.immunization-sd.org and go to the Health Care Providers section, or call 619-692-8661. National Immunization Awareness Month information is available at the Partners for Immunizations website at www.partnersforimmunization.org.