Research ArticleHEALTH AND MEDICINE

Transmission dynamics of and insights from the 2018–2019 measles outbreak in New York City: A modeling study

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Science Advances  27 May 2020:
Vol. 6, no. 22, eaaz4037
DOI: 10.1126/sciadv.aaz4037
  • Fig. 1 Epidemic curve.

    (A) Monthly incidence and (B) incidence rate (i.e., cases per 100,000 population) for all ages and by age group. The solid line (y axis on the right) shows monthly numbers for all ages, reported as of 6 August 2019. For comparison, bars (y axis on the left) show monthly numbers for <1-year-old (blue), 1- to 4-year-olds (red), 5- to 17-year-olds (yellow), and 18+-year-olds (gray), respectively, estimated on the basis of health reports. The x axis shows time in month (yy/mm).

  • Fig. 2 Model fit.

    Box plots show estimates of monthly incidence for all ages (A), percentage of cases reported in each age group (B), and monthly incidence for <1-year-olds (C), 1- to 4-year-olds (D), 5- to 17-year-olds (E), and 18+-year-olds (F). Results are pooled over all 10 model inference runs (each with 10,000 and in total 100,000 model realizations). Horizontal thick lines show the median of model estimates; box edges show the 25th and 75th percentiles; whiskers show the 2.5th and 97.5th percentiles; and dots show outliers. Stars (*) in (A) and (B) show monthly incidence for all ages and the age distribution, reported as of 6 August 2019; crosses (×) in (C) to (F) show age-grouped monthly incidence estimated from health reports. The x axis shows time in month (yy/mm).

  • Fig. 3 Estimated changes in population susceptibility.

    Red lines and surrounding regions (y axis on the left) show the mean and 50 and 95% CrIs of estimates pooled over all 10 model inference runs (100,000 model realizations in total) for <1-year-olds (A), 1- to 4-year-olds (B), 5- to 17-year-olds (C), and 18+-year-olds (D), respectively, at the end of each month from September 2018 to July 2019. The initial susceptibilities, estimated at the end of September 2018, were computed by adding the total numbers of individuals immunized by the vaccination campaigns in October 2018 to the posterior estimates at the end of October 2018. For comparison, the gray bars (y axis on the right) show estimated numbers of individuals immunized during the vaccination campaigns; note that the vaccination campaigns targeted individuals under 19 years and thus is not shown for 18+-year-olds.

  • Fig. 4 Estimates of key model parameters.

    (A) the basic reproductive number, (B) the effective reproductive number, (C) infectious period, (D) relative contact rate among 1- to 4-year-olds, (E) relative contact rate among 5- to 17-year-olds, and (F) relative contact rate among 18- to 49-year-olds. Red lines and surrounding regions (y axis on the left) show the mean and 50 and 95% CrIs of estimates pooled over all 10 model inference runs (100,000 model realizations in total) made at the end of each month from October 2018 to July 2019. For comparison, the gray bars (y axis on the right) show monthly incidence for all ages (A to C) or the related age groups (D to F).

  • Fig. 5 Estimated negative impact of measles parties and positive impact of vaccination campaigns.

    Top row: Simulated estimates of monthly incidence, should there be no measles parties, for all ages (A), <1-year-olds (B), 1- to 4-year-olds (C), 5- to 17-year-olds (D), and 18+-year-olds (E). Bottom row: Simulated estimates of monthly incidence, should there be no vaccination campaigns, for all ages (F), <1-year-olds (G), 1- to 4-year-olds (H), 5- to 17-year-olds (I), and 18+-year-olds (J). Results are pooled over 10,000 model simulations. Horizontal thick lines show the median of model estimates; box edges show the 25th and 75th percentiles; whiskers show the 2.5th and 97.5th percentiles; and dots show outliers. For comparison, stars (*) in (A) and (F) show monthly incidence for all ages, reported as of 6 August 2019; crosses (×) in (B) to (E) and (G) to (J) show age-grouped monthly incidence estimated from health reports.

  • Table 1 Estimated proportion of infections caused by each age group.

    Rows show the receiving (i.e., infectee) age groups, and columns show the sources of infection (i.e., infector age groups). The numbers are the mean (95% CrI) estimates in percentage. For instance, for <1-year-olds (top row), on average, 16.3% of cases were infected by the same age group, 44.6% by 1- to 4-year-olds, 20.9% by 5- to 17-year-olds, 15.2% by 18- to 49-year-olds, and 3% by 50+-year-olds.

    Infectee
    age
    groups
    Infector age groups
    <1 year1–4
    years
    5–17
    years
    18–49
    years
    50+
    years
    <1 year16.3
    (12.3–21.0)
    44.6
    (35.5–53.5)
    20.9
    (13.9–28.4)
    15.2
    (9.6–21.6)
    3.0
    (1.4–5.0)
    1–4 years1.8
    (1.0–3.0)
    85.8
    (77.0–91.9)
    7
    (3.2–12.9)
    5
    (2.2–9.3)
    0.3
    (0.1–0.6)
    5–17 years1.5
    (0.9–2.4)
    12.9
    (6.9–21.3)
    80.9
    (70.4–88.4)
    4.4
    (2.0–8.0)
    0.3
    (0.1–0.5)
    18–49 years2.4
    (1.5–3.7)
    18.6
    (10.9–28.0)
    9.1
    (4.8–14.9)
    69.5
    (56.2–80.8)
    0.4
    (0.2–0.8)
    50+ years15.5
    (11.6–19.9)
    40.1
    (31.1–49.3)
    19.7
    (13.0–27.0)
    15.6
    (9.7–22.4)
    9.1
    (3.8–16.3)
  • Table 2 Estimated negative impact of measles parties and positive impact of vaccination campaigns during October 2018 to July 2019.

    Column 2 shows the observed numbers of cases, reported as of 6 August 2019. Column 3 shows the estimated numbers of cases if there had been no measles parties. Columns 4 to 6 show the estimated total numbers of cases (fourth column), hospitalizations (fifth column), and individuals in intensive care unit (ICU) for different age groups (rows 3 to 6) and overall (last row), if there had been no vaccination campaigns. Columns 7 to 9 show the estimated numbers of cases, hospitalizations, and ICU cases averted by the vaccination campaigns. Numbers are the median (IQRs) of 10,000 simulations. See table S2 for the median and 95% CIs of the simulated estimates.

    Age
    group
    No. of cases
    reported
    No. of cases,
    if no measles
    parties
    No. if no vaccination campaignsNo. averted by vaccination campaigns
    CasesHospitalizationsICU casesCasesHospitalizationsICU cases
    <110026 (2–81)1302
    (1062–1358)
    97 (79–101)20 (16–21)1202
    (962–1258)
    89 (72–94)18 (15–19)
    1–427562 (5–193)3914
    (3596–4000)
    291 (267–297)60 (55–62)3639
    (3321–3725)
    271 (247–277)56 (51–57)
    5–1713826 (1–110)1412
    (897–1534)
    105 (67–114)22 (14–24)1274
    (759–1396)
    95 (56–104)20 (12–21)
    18+12929 (2–102)1141
    (907–1218)
    85 (67–91)18 (14–19)1012
    (778–1089)
    75 (58–81)16 (12–17)
    All642152 (12–492)7810
    (6480–8089)
    581 (482–601)120 (100–124)7168
    (5838–7447)
    533 (434–554)110 (90–115)

Supplementary Materials

  • Supplementary Materials

    Transmission dynamics of and insights from the 2018–2019 measles outbreak in New York City: A modeling study

    Wan Yang

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    • Tables S1 to S3
    • Figs. S1 and S2
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