Table 4.
Prevalence of patterns of undervaccination among U.S. children ages 0–19 months, 2017 National Immunization Survey-Child, n=15,333
| Overall frequency of undervaccination patterns | Completed combined 7-vaccine series by age 19 months | Average days undervaccinated for the combined 7-vaccine series | ||
|---|---|---|---|---|
| Pattern | n (column %)a | n (row %)a | Mean (±SE)b | Median (IQR) |
| n=15,333 | ||||
| All vaccines received on-time (zero days undervaccinated) | 7,139 (41.7) | 7,139 (100%) | 0 days (±0.0) | 0 (0–0) |
| Undervaccination patternsc indicating parental hesitancy | ||||
| Restrictive shot-limiting: | ||||
| At least 6 visits with ≤3 vaccines at each visit before age 19 months | 761 (5.3) | 182 (24.3%) | 80.8 days (±8.9) | 34.7 (15.3–115.2) |
| Episodic shot-limiting: | ||||
| At least 1 immunization visit with ≤2 vaccines before age 15 months and no more than 2 immunization visits with ≥3 vaccinesd | 583 (4.4) | 80 (10.4%) | 185.7 days (±11.9) | 164.5 (57.7–309.5) |
| Selective vaccination: | ||||
| Did not start a recommended vaccine series | 1,681 (11.2) | 0 (0%) | 250.2 days (±7.6) | 228.0 (47.0–487.4) |
| Undervaccination patterns indicating delayed start e | ||||
| Delayed start: | ||||
| Received first combined 7-vaccine series dose at age 3 months or later | 125 (1.2) | 30 (16.9%) | 264.4 days (±39.2) | 247.7 (104.6–442.4) |
| Other undervaccination patterns | ||||
| Missing doses: | ||||
| Started all series, missing dose(s) needed to complete series | 3,118 (22.6) | 0 (0%) | 45.4 days (±2.0) | 16.5 (0.3–63.9) |
| All doses received, some or all late: | ||||
| Completed all recommended series, but some or all doses were late | 1,926 (13.6) | 1,926 (100%) | 23.6 days (±1.1) | 14.0 (5.2–30.8) |
Abbreviations: SE, standard error
The unweighted number is presented alongside a weighted percentage
Mean (SE) presented are weighted
When classifying vaccination patterns, vaccine doses in the 7-combined vaccine series (diphtheria-tetanus-acellular pertussis, poliovirus, measles-mumps-rubella, Haemophilus Influenzae type b, hepatitis B, varicella, and pneumococcal conjugate vaccines) were considered, with the exception of the restrictive and episodic shot-limiting patterns. For the shot-limiting patterns, all vaccine doses given at immunization visits were considered, including oral rotavirus doses, and combination vaccines were counted as one vaccine.
For the episodic shot-limiting pattern, children had to have at least two immunization visits, and the requirement of at least 1 immunization visit with ≤2 vaccines did not include individual Hepatitis B vaccines given within 6 weeks of birth or influenza vaccines.
Delayed start patterns can indicate either parental hesitancy or other barriers to accessing immunization services