HPV vaccination is highly effective but remains underused in the U.S.

Since human papillomavirus (HPV) vaccines were first added to the routine U.S. childhood immunization schedule nearly two decades ago, the evidence of their effectiveness has become stronger every year.

In 2019, a Medicine by the Numbers in American Family Physician summarized a Cochrane review of 26 randomized, controlled trials comparing HPV vaccines to placebo. The authors found that vaccination reduced the risk of precancerous cervical lesions (cervical intraepithelial neoplasia [CIN] grades 2 or 3 and adenocarcinoma in situ) with numbers needed to treat (NNT) ranging from 55 to 73, depending on participants’ baseline HPV status. A 2021 observational study of girls and young women in England found that vaccination at ages 16-18, 14-16, and 12-13 years was associated with reductions in cervical cancer of 34%, 62%, and 87%, respectively. Remarkably, a study published this year found that 30,000 Scottish women who received at least one dose of HPV vaccine at age 12 or 13 had developed zero cases of invasive cervical cancer 11 to 20 years later!

Nonetheless, HPV vaccination coverage among U.S. adolescents remains lower than that for other childhood vaccines. Although coverage has gradually increased over time, an analysis of 2022 National Immunization Survey (NIS) data found that only 69% of 13 year-olds and 77% of 17 year-olds had received at least one dose, and 50% and 68% of these respective age groups were up-to-date (had received 2 doses if starting the series before age 15, or 3 doses if starting later). In comparison, 90% of 17 year-olds had received a least one dose of tetanus, diphtheria, and acellular pertussis (Tdap) and at least 2 doses of measles, mumps, and rubella (MMR) vaccines.

Historically, children living in socioeconomically disadvantaged households have been less likely to be up-to-date on immunizations. The Centers for Disease Control and Prevention’s Vaccines for Children program, which celebrates its 30th anniversary this year, aims to eliminate disparities in access by providing vaccines at no cost to children who are uninsured, Medicaid-eligible, American Indian or Alaska Natives.

A recent study of the 2017-2021 NIS examined factors associated with the intent to vaccinate by socioeconomic status and education level among parents of adolescents who had not received HPV vaccine. Participating parents were considered “advantaged” if their income was greater than 200% of the federal poverty level and they had at least a high school education; parents with lower incomes who had not completed high school were considered “deprived.” Surprisingly, 65% of advantaged parents of unvaccinated adolescents reported no intent to vaccinate in the future, compared to 41% of parents in the deprived group. Reasons for not vaccinating also differed between the groups: the advantaged group most often cited “safety concerns,” while the deprived group reported “lack of knowledge,” “not recommended,” and “not needed.” These data suggest that HPV vaccine hesitant parents may respond to different approaches.

In a 2015 AFP editorial, Drs. Herbert Muncie and Alan Lebato advised presenting the vaccine’s benefit as cancer prevention rather than focusing on HPV as a sexually transmitted infection, and taking a non-judgmental approach when explaining the recommendation to vaccinate:

To improve acceptance of immunizations, physicians must be knowledgeable about vaccine safety and effectiveness, and non-judgmental about parents' beliefs. … Hesitant parents may respond to the CASE method: the physician corroborates the parents' concerns, talks about his or her own experience with the vaccine, summarizes the science about vaccine effectiveness and safety, and explains advice in terms of the child's health.

Regarding safety, the World Health Organization’s Global Advisory Committee on Vaccine Safety has repeatedly found no evidence of a causal association between HPV vaccination and a variety of serious adverse effects.

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This post first appeared on the AFP Community Blog.

Deadly drivers and the limits of preventive counseling

I believe that I'm a pretty safe driver. I don't use my phone in the car except for calls on my Bluetooth hands-free system, I come to a complete stop at stop signs even when no one else is around, and I never get in the driver's seat after I've been drinking. During the fall of 2020 and spring of 2021, though, I paid more attention than usual to driving safely. Our auto insurance company offered a discount for installing a device in my car that monitored my driving behavior, and my then 15 year-old son (in Utah, the minimum age for a learner's permit is 15) began learning to drive.

There has been a lot of media attention in recent months to the increase in distracted driving and its deadly consequences since the start of the pandemic. After falling for decades thanks to legislation mandating safety features such as airbags to a low of 32,479 in 2011, annual traffic-related deaths (including pedestrians) gradually rose, then spiked during the pandemic from 38,824 in 2020 to 42,795 in 2022. This statistic is similar to the 48,000 firearm homicides and suicides that occur in the U.S. every year.

Why have traffic-related deaths been going in the wrong direction? A New York Times Magazine story highlighted deferred road maintenance, larger and more powerful vehicles, aggressive driving and road rage, and the perennial culprit, intoxicated drivers. A recent analysis of data from the National Highway Traffic Safety Administration found that 1 in 5 deaths of child passengers in motor vehicle crashes involved an alcohol-impaired driver (blood alcohol concentration > 0.08 g/dL), and the more impaired the driver was, the less likely the child was to be wearing a seat belt.

 A Vox story pointed the finger at smartphones, noting that a company that sells a more sophisticated version of the device I installed in my car a few years ago - an app that measures phone motion and screen interaction while driving - found that in 2022, drivers interacted with their phones on nearly 58% of trips (an average of 2 minutes, 11 seconds per hour), more than one-third while driving over 50 miles per hour. This is when they knew the app was monitoring their behavior; one wonders if they would have been on their phones even more without it.

The difference between a medical and a public health problem is often merely a matter of perspective. For example, the solution to the medical problem of hypertension is to screen patients for high blood pressure and put the ones whom we diagnose on medications and/or encourage them to be more physically active and eat differently. But treating high blood pressure as a medical problem has been an abysmal failure. According to the National Health and Nutrition Examination Survey, of the one-third of Americans who had hypertension from 2017-2020, more than half had uncontrolled blood pressure (>140/90 mm Hg) and even among patients taking blood pressure medication, nearly one-third had uncontrolled blood pressure. Zoom out from the office setting to communities, counties, and states, and it's easy to see that hypertension is really a public health problem: too much sodium in food, too little access to safe places to exercise without a gym membership, difficulty getting a primary care appointment due to insufficient supply and uneven distribution, and so on.

Is impaired driving a medical or a public health problem? I got a lot of flak from readers when I wrote in a Medscape commentary that I would report to law enforcement a patient who declined to stop driving while high on cannabis. Clinical guidelines recommend counseling parents and guardians about keeping their children in rear-facing car seats until age two, using age and size-appropriate car and booster seats, and having children age 13 and younger ride exclusively in the back seat. With any adolescent approaching the minimum age for a learner's permit (16 years in Pennsylvania), I spend time during the well-child visit discussing the dangers of driving and texting, substance use before or while driving, and getting into a car with an impaired or distracted driver. Perhaps my counseling has saved a few lives over the past 20 years, but it's never been proven that this type of counseling improves health outcomes.

However, the evidence is clear that public health interventions and laws reduce motor vehicle crash injuries and deaths. The Community Preventive Services Task Force has evaluated a long list of interventions that save lives by reducing alcohol-impaired driving and increasing use of child safety seats, seat belts, and motorcycle helmets. The Vox story cited data that associated the passage of "hands free" phone laws with reductions in phone motion and driver distractions, but a lack of enforcement may cause these bad habits to reassert themselves over time.