The more vaccines children get at any one office visit between the ages of 4 and 6 years, the more fearful they are of needles later on and the less likely they are to start human papillomavirus vaccine (HPV) as adolescents, according to an investigation of 120 children.

Shot-stacking between ages 4 and 6 years is not uncommon, especially if children might not be back in the office any time soon. Although it’s convenient and often better reimbursed to give all the recommended 4- to 6-year-old shots – MMR, DTaP, varicella, IPV, and maybe flu and hepatitis B vaccines – in one visit, the investigators found a hidden cost.

For some children, the trauma of being pinned down for shot after shot leaves a lasting impression that makes them shy away from needles, and maybe even medical care, later on.

“We don’t need to change the vaccine schedule,” but we do have to be careful because 4- to 6-year-olds are especially vulnerable to phobias. “I think the best thing would be to give one vaccine at age 4, two at age 5, and two at age 6,” years, said lead investigator and pediatric emergency physician Amy Baxter, MD, a clinical associate professor at the Medical College of Georgia, Augusta.

“I’ve dealt with needle phobia in the ED. These kids come in and they are already freaked out about needles. If they get diagnosed with diabetes or leukemia, parents don’t think they are going to be able to handle it,” she said in an interview.

Expanded school vaccination programs might help by making it more convenient for parents to space out shots. The development of patch, microneedle, or effective sublingual or intranasal options also would help.

Dr. Baxter and her colleagues asked 120 children aged 10 to 12 years old to rate their fear of needles on a visual analogue scale (VAS), from 0 points meaning no fear to 100. The investigators matched the scores against the children’s immunization records (Vaccine. 2017 Jun 20. doi: 10.1016/j.vaccine.2017.06.029).

There was no significant relationship between needle fear and the total number of injections. However, fear did correlate with the number of shots children received in 1 day from ages 4 to 6 years old. Six children (50%) who had four same-day injections during that period scored in the upper quartile of anxiety as adolescents (VAS greater than 83), versus 22 (27%) who had three, and 2 (10%) who had two. None of the children who had just one shot per office visit as preschoolers were very worried about needles (P = .0387).

The investigators found that the likelihood of being in the upper quartile of fear as adolescents increased with each additional same-day injection between the ages of 4 and 6 years (odds ratio, 3.108; 95% confidence interval, 1.311-7.367; P = .01).

The team checked back with the children a few years later to see who had started HPV immunizations by age 14 years. Just 27% of children in the upper quartile of needle fear had done so, versus 48% in the least anxious quartile (VAS less than 32). The study wasn’t powered to detect a statistically significant difference in HPV vaccine uptake, but decreased uptake with higher needle fear came close (OR, 2.57; 95% CI, 0.864-7.621; P = .0889).

“It’s the stacking that causes fear. There was no difference in the uptake of vaccines when they were spread out, but more shots” at one time “causes more distress, so there was a difference in fear 5 years later,” Dr. Baxter said.

The investigators also assessed parental concerns about immunizations. “What was interesting was that whether the parents were in the upper or lower quartile of anxiety didn’t impact HPV initiation at all. The children’s anxiety 2 years earlier seemed much more relevant,” Dr. Baxter said.

In a literature review of 15 studies from 1958-2016 that included over 8,000 subjects, the investigators also found that needle fear tracked neatly with the sixfold increase in scheduled vaccines since the 1970s, with more than 60% of people now endorsing some degree of injection anxiety – more than ever before. “The curve of increasing needle fear correlated strongly with increasing vaccine number,” they found (Kendall’s tau b = 0.747; 95% CI, 0.513-0.982; P = .0003).

As two-thirds of the literature review sample were adults, “these results imply that fear acquired in childhood persists,” they concluded.

The majority of children in the study were white. Their mothers were a mean of 44 years, with a mean education level of 18 years. Demographic differences didn’t affect needle fear.

Dr. Baxter is a pediatric pain researcher and the inventor of Buzzy, a bumblebee shaped vibrator to distract children and relieve pain during shots. When asked if readers could trust her study findings given her interest in selling the device, she noted that, in a previous study, “Buzzy for 15 seconds did not work well for 4 to 6 year olds” getting multiple injections at one office visit. “Buzzy is not the solution for giving four shots at once.”

aotto@frontlinemedcom.com

Childhood vaccine trauma decreases adolescent HPV immunization uptake