More Parents Delaying Vaccines; Most Children Never Catch Up

Troy Brown

June 18, 2012

June 18, 2012 — A retrospective cohort analysis of prevalence and trends in compliance with alternative vaccination schedules found more parents following alternate schedules, and when they do, their children may not receive all recommended vaccines. Compliance was measured by consistent shot-limiting (ie, receiving no more than 2 vaccines at any provider visit between birth and 9 months of age) in a metropolitan area of Oregon.

Steve G. Robison, BS, a sentinel epidemiologist in the Oregon Immunization Program of the Oregon Health Authority in Portland, and colleagues published their results in the June 18 issue of Pediatrics.

They studied children born between July 2003 and October 2009 whose most recent place of residence was within the Oregon Sentinel Immunization Surveillance region, which represents the core of metropolitan Portland and is part of a US Centers for Disease Control and Prevention (CDC)-sponsored surveillance system that covers multiple sites in the United States. Vaccination records and demographic information were retrieved from the ALERT Immunization Information System.

Children were categorized into 1 of 3 groups: consistent shot-limiters, episodic limiters, and nonlimiters. Consistent shot-limiters were defined as children who received no more than 2 vaccines at any provider visit between birth and 9 months of age.

Advisory Committee on Immunization Practices (ACIP) guidelines, which are supported by the American Academy of Pediatrics, the American Academy of Family Physicians, and the CDC, generally require more than 2 vaccinations at the 2-, 4-, and 6-month visits.

Reasons for parental reluctance to vaccinate their children include doubts about vaccine safety, mistrust of pharmaceutical companies and governments involved with vaccination, concern that too many vaccines are being given to young children, concern about pain caused by multiple injections, fear of giving vaccines to a child who is ill, and uncertainty about the need for certain vaccines.

Alternative Vaccination Schedules

"In response to these concerns, alternative vaccination schedules offering variations on the ACIP schedule while legitimizing parental worries have circulated widely through television, books, and Internet sources," the authors write.

These alternative schedules generally have 3 common elements: delayed receipt of some vaccines/doses, selective avoidance of other vaccines, and limiting the number of vaccines given at any 1 provider visit. These approaches typically require an increased number of provider visits to fit in all required vaccinations.

The authors note that 2 frequently used alternative schedules were published by Stephanie Cave, MD, in 2001 and Robert Sears, MD, in 2007.

The schedule that Dr. Cave published, which was revised in 2007, requires a total of 5 visits at 4, 5, 6, 7, and 8 months of age. She also recommends avoiding the rotavirus vaccine altogether and delaying the pneumococcal vaccine until the child's second year of life.

Dr. Sears' schedule recommends a total of 6 visits at 2, 3, 4, 5, 6, and 7 months, and has children receiving all recommended vaccines by the age of 9 months except for the polio and hepatitis B (HepB) vaccine.

Both physicians recommend avoiding the HepB vaccines during the first 2 years of the child's life unless the birth mother is positive for the HepB surface antigen.

Of 97,711 children studied, 70,758 children were nonlimiters, 22,451 were episodic limiters, and 4502 (4.6%) were consistent limiters.

Shot-limiting rates among birth cohorts ranged from 1.9% for the February 2006 birth cohort to 11.6% for the October 2009 birth cohort

Shot-limiting rates declined from 3.7% to 2.3% for children born between July 2003 and November 2006, where the average monthly percentage change (MPC) was −1.2% of the limiting rate (95% confidence interval [CI], −1.6% to −0.8% per month).

Rates increased rapidly from 2.5% for the November 2006 birth cohort to 9.3% for the September 2008 birth cohort. During this period, the MPC in limiting rate was 6.8% per month (95% CI, 5.9% - 7.7% per month).

No discernible change in rates was observed after September 2008 (MPC rate, 0.1%). During the first 9 months of age, consistent shot-limiters were given an average of 6.4 vaccination injections across 4.2 vaccination visits, with an average of 1.5 injections per visit. Nonlimiters and episodic limiters received an average of 10.4 injections across 3.2 immunization visits, with an average of 3.2 injections per visit (P < .01).

Significant gaps existed between consistent shot-limiters and all others for age-appropriate receipt of all vaccines by the age of 9 months. The greatest difference was for the HepB primary vaccine series (28.0% series completion for consistent limiters vs 92.1% for nonlimiters and episodic limiters). The smallest difference was observed for the Hib series (54.3% series completion for consistent limiters vs 81.8% for nonlimiters and episodic limiters).

Failure to Catch Up

"At 9 months of age, the consistent limiters were substantially less likely to be caught up for any immunization series than nonlimiters or episodic limiters (average relative risk [RR]: 0.55)," the authors write.

By the age of 19 months, the risk was attenuated for vaccinations that were due by 9 months (average RR, 0.72), but the gap for vaccinations due by 19 months remained stable (average RR, 0.54).

At 19 months of age, consistent limiters were also less likely on average to have been given the varicella, hepatitis A, or measles-mumps-rubella vaccines (average RR, 0.48). These vaccinations are not due until after the first year of age.

Most of the consistent shot-limiters failed to follow the alternative schedules developed by Dr. Cave or Dr. Sears. Only 0.9% (40/4502 consistent limiters across entire period) followed Dr. Cave's schedule, and only 3.2% (81/2517 consistent limiters after October 2007 schedule release) followed Dr. Sears' schedule.

"We believe that the pattern of consistent shot-limiting is indicative of an increase in parental demand and provider accommodation for less than full compliance with the ACIP vaccination schedule. Although the identified pool of consistent shot-limiters is small, this group has translated their worries about vaccines into action and may represent the concerns of a larger proportion that may only episodically limit or delay, or who may have trouble finding accommodating providers," the authors write.

The study was funded by Oregon's Sentinel Immunization Grant from the Centers for Disease Control and Prevention. The authors have disclosed no relevant financial relationships.

Pediatrics. 2012;130:32-38.

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