Neil Osterweil

May 05, 2015

BOSTON — When it comes to vaccinations, primary care practitioners are the guardians of public health, but recent measles outbreaks have shown that renewed vigilance is needed, according to one vaccine expert.

"Vaccines are one thing we do as physicians that are really important to society and important to the world in general. They prevent a lot of disease in a lot of adults and children," said Michael Donnelly, MD, from MedStar Georgetown University Hospital in Washington, DC.

Dr Donnelly discussed recent changes in vaccines, vaccine-preventable diseases, and gaps in clinical practice that can adversely affect vaccine use here at the American College of Physicians Internal Medicine 2015.

For human papillomavirus (HPV), in addition to genotypes 6, 11, 16, and 18 targeted by the quadrivalent vaccines, the new 9-valent vaccine is 96% effective against genotypes 31, 33, 45, 52, and 58.

More than 90% of anal and cervical cancers and 60% of penile cancers are HPV-positive. It is expected that switching to the 9-valent HPV vaccine will further reduce the incidence of cervical intraepithelial neoplasia of grades 2 and 3 and other precancerous lesions by about 19%, and the incidence of cervical cancer by about 14%.

"When you look at cost–benefit ratios, most of the bang for your buck is in getting to all girls. When you do that, obviously you're going to reduce cervical rates," Dr Donnelly explained.

New HPV Vaccine

The Advisory Committee on Immunization Practices at the Centers for Disease Control and Prevention recommends the three-dose series for 11- and 12-year-old girls — many school districts require the vaccine before entry into the sixth grade — and for women up to 26 years of age.

In the United States, 57.0% of girls receive one of the three prescribed doses, and 37.6% receive all three. Although only about 70% of girls who start the series get all three doses, this in an increase over the 2012 rate of 53.8%, he pointed out.

The vaccine can also reduce anal cancers and penile cancers, so it is recommended for 11- or 12-year-old boys, although it can be started as early as 9 years. It is also recommended for males 13 to 21 years who have not been previously vaccinated, and for men who have sex with men and HIV-positive men up to 26 years of age. Approximately 35.0% of males have received one dose, up from 20.8% in 2012.

For bacterial meningitis, the meningococcal polysaccharide vaccine contains antigens to serogroups A, C, Y, and W-135, and protects against 85% to 100% of disease.

Because the ability to evoke a T-cell response, which confers immunity, wanes over time, revaccination every 5 years is necessary for high-risk patients.

Meningococcal Vaccines

It is important for clinicians to remember that young adults might not have had a booster of the quadrivalent vaccine at age 16, Dr Donnelly said.

The MCV4 meningococcal conjugate vaccine, introduced in 2005, contains the same serogroups as the diphtheria toxoid conjugate vaccine. These vaccines have the advantage of being able to eradicate nasopharyngeal carriage, which induces a herd-immunity effect. They also appear to confer long-term immunity through T-cell activation, which could decrease the need for booster doses.

Menigococcal serogroup B, responsible for five meningitis outbreaks on college campuses from 2009 to 2013, is covered by two vaccines approved for use only in outbreaks: Trumenba (Pfizer) and Bexsero (Novartis). Reverse vaccinology — a genomic reverse-engineering technology — was used to rapidly create these vaccines.

For invasive pneumococcal disease, PPSV23, a 23-valent polysaccharide pneumococcal vaccine (Pneumovax), is available in the United States, as is a 7-valent conjugated vaccine (PCV7) and 1-valent vaccine (Prevnar 13, Wyeth/Pfizer).

PPSV23 is moderately effective at reducing invasive pneumococcal disease, but is poor at preventing nonbacteremic pneumococcal pneumonia, which is about 10 times more common than bacteremic pneumonia in adults, Dr Donnelly said.

Pneumococal Vaccines

Immunocompetent patients with chronic heart, lung, or liver disease, or who have diabetes mellitus, are alcoholic, or smoke are candidates for vaccination with PPSV23 alone. However, immunocompetent patients who have either cerebrospinal fluid leak or cochlear implants can also receive PCV13.

The Advisory Committee on Immunization Practices recommends PCV13 first for immunocompetent patients, followed, at least 8 weeks later, by PPSV23. If the patient has previously received PPSV23, the clinician should wait 1 year before giving PCV13. This vaccine is used off-label in patients 19 to 49 years of age, but is commonly given, Dr Donnelly reported.

Patients who are immunocompromised should receive both PPSV23 and PCV13, and PPSV23 should be repeated 5 years after the first dose. The vaccine is licensed for patients 50 years and older to prevent postherpetic neuralgia, which is very painful and difficult to treat.

In practice, because the vaccine becomes less effective over time, many clinicians prefer to wait until the patient is 60 years before administering.

In 2014, there were 28,639 reported cases of pertussis, or whooping cough, in the United States, nine of which resulted in death, primarily in babies, who are most vulnerable.

Pertussis

The Advisory Committee on Immunization Practices now recommends vaccination against pertussis in women during every pregnancy because of the rapid decline in antibodies after immunization with the acellular pertussis vaccine currently in use. Dr Donnelly pointed out that this use is off-label.

There is some evidence to suggest that antibody responses are significantly better when women are vaccinated at 27 to 30 weeks of gestation, he said.

Several practice-based strategies can increase demand for vaccination in the community, such as incentive rewards, reminder and recall systems, clinic-based education, and manual outreach and tracking, Dr Donnelly explained.

In addition, health policy makers can help to ensure expanded vaccine access, home visits for immunizations, and reduced out-of-pocket costs.

Anecdotally, he reported that pediatrician colleagues of his make sure that vaccines are readily available at every visit, educate staff about indications, coordinate with other healthcare services, provide vaccination in a medical home setting when possible, and review immunization status at every encounter.

Good relationships and communication are essential to getting patients to adhere to vaccines, said Sharon Krieger, MD, from the Mount Kisco Medical Group in New York.

"My patients trust me and think I'm doing what's best for them," she told Medscape Medical News. "I have long-term relationships with patients I've been in practice with over 20 years, and patients mostly do what I tell them."

The recommendation about vaccination at each pregnancy is new to her, but she said she will discuss it with her colleagues in obstetrics and gynecology to evaluate.

Dr Donnelly and Dr Krieger have disclosed no relevant financial relationships.

American College of Physicians (ACP) Internal Medicine 2015. Presented April 30, 2015.

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