In 2010, the World Health Assembly (WHA) set the following three milestones for measles
control to be achieved by 2015: 1) increase routine coverage with the first dose of
measles-containing vaccine (MCV1) among children aged 1 year to ≥90% at the national
level and to ≥80% in every district, 2) reduce global annual measles incidence to
<5 cases per 1 million population, and 3) reduce global measles mortality by 95% from
the 2000 estimate* (
1
). In 2012, WHA endorsed the Global Vaccine Action Plan,
†
with the objective of eliminating measles
§
in five of the six World Health Organization (WHO) regions by 2020. This report describes
progress toward WHA milestones and regional measles elimination during 2000–2019 and
updates a previous report (
2
). During 2000–2010, estimated MCV1 coverage increased globally from 72% to 84% but
has since plateaued at 84%–85%. All countries conducted measles surveillance; however,
approximately half did not achieve the sensitivity indicator target of two or more
discarded measles and rubella cases per 100,000 population. Annual reported measles
incidence decreased 88%, from 145 to 18 cases per 1 million population during 2000–2016;
the lowest incidence occurred in 2016, but by 2019 incidence had risen to 120 cases
per 1 million population. During 2000–2019, the annual number of estimated measles
deaths decreased 62%, from 539,000 to 207,500; an estimated 25.5 million measles deaths
were averted. To drive progress toward the regional measles elimination targets, additional
strategies are needed to help countries reach all children with 2 doses of measles-containing
vaccine, identify and close immunity gaps, and improve surveillance.
Immunization Activities
WHO and the United Nations Children’s Fund (UNICEF) determine vaccination coverage
using data from administrative records (calculated by dividing the number of vaccine
doses administered by the estimated target population, reported annually) and vaccination
coverage surveys, to estimate MCV1 and second dose measles-containing vaccine (MCV2)
coverage through routine (i.e., not through mass campaigns) immunization services.
¶
During 2000–2010, estimated MCV1 coverage increased worldwide from 72% to 84%; however,
coverage has remained at 84%–85% since 2010, with considerable regional variation
(Table 1).
TABLE 1
Estimates of coverage with the first and second dose of measles-containing vaccine
administered through routine immunization services, reported measles cases, and incidence
by World Health Organization (WHO) region — worldwide, 2000, 2010, 2016, and 2019
WHO region/Year (no. of countries in region)
Percentage
No. of reported measles cases†
Measles incidence per 1 million population†,§
MCV1* coverage
Countries with ≥90% MCV1 coverage
MCV2* coverage
Reporting countries with <5 measles cases per 1 million population
African
2000 (46)
53
9
5
8
520,102
836
2010 (46)
73
37
4
30
199,174
232
2016 (47)
69
34
23
51
36,269
37
2019 (47)
69
32
33
34
618,595
567
Americas
2000 (35)
93
63
65
89
1,754
2
2010 (35)
93
74
67
100
247
0.3
2016 (35)
92
66
80
100
97
0.1
2019 (35)
88
71
75
91
19,244
28
Eastern Mediterranean
2000 (21)
71
57
28
17
38,592
90
2010 (21)
77
62
52
40
10,072
17
2016 (21)
82
57
74
55
6,275
10
2019 (21)
82
52
75
42
18,458
27
European
2000 (52)
91
62
48
45
37,421
50
2010 (53)
93
83
80
69
30,625
34
2016 (53)
93
81
88
82
4,440
5
2019 (53)
96
85
91
32
105,755
116
South-East Asia
2000 (10)
63
30
3
0
78,558
51
2010 (11)
83
45
15
36
54,228
30
2016 (11)
89
64
75
27
27,530
14
2019 (11)
94
73
83
30
29,239
15
Western Pacific
2000 (27)
85
48
2
30
177,052
105
2010 (27)
96
63
87
68
49,460
27
2016 (27)
96
63
91
68
57,879
31
2019 (27)
94
67
91
46
78,479
41
Totals
2000 (191)
72
45
18
38
853,479
145
2010 (193)
84
63
42
60
343,806
50
2016 (194)
85
61
67
70
132,490
18
2019 (194)
85
63
71
46
869,770
120
Abbreviations: MCV1 = routine first dose of measles-containing vaccine; MCV2 = routine
second dose of measles-containing vaccine.
* http://www.who.int/immunization/monitoring_surveillance/data/en; data as of July
15, 2020.
†
http://apps.who.int/immunization_monitoring/globalsummary/timeseries/tsincidencemeasles.html;
data as of July 15, 2020.
§ Population data from United Nations, Department of Economic and Social Affairs,
Population Division, 2020. Any country not reporting data on measles cases for that
year was removed from both the numerator and denominator in calculating incidence.
Among 194 WHO member states, 122 (63% of member states) achieved ≥90% MCV1 coverage
in 2019, a 42% increase from 86 (45%) countries in 2000, but a 4% decrease from a
peak of 127 (65%) countries in 2012. In 2019, 42 (22%) countries achieved MCV1 coverage
≥90% nationally and ≥80% in all districts**; however, during that year 19.8 million
infants did not receive MCV1 through routine immunization services. The six countries
with the highest numbers of infants who had not received MCV1 were Nigeria (3.3 million),
Ethiopia (1.5 million), Democratic Republic of the Congo (DRC) (1.4 million), Pakistan
(1.4 million), India (1.2 million), and Philippines (0.7 million), accounting for
nearly half (48%) of the world’s total.
Estimated global MCV2 coverage nearly quadrupled from 18% in 2000 to 71% in 2019,
largely because of an 86% increase in the number of countries providing MCV2, from
95 (50%) countries in 2000 to 177 (91%) in 2019 (Table 1). Six countries (Cameroon,
Ethiopia, Liberia, Mali, Republic of the Congo, and Togo) introduced MCV2 in 2019.
Approximately 204 million persons received MCV during supplementary immunization activities
(SIAs)
††
in 55 countries in 2019; in addition, 9 million persons received MCV during measles
outbreak response activities.
Reported Measles Incidence
In 2019, all 194 countries conducted measles surveillance, and 193
§§
(99%) had access to standardized quality-controlled laboratory testing through the
WHO Global Measles and Rubella Laboratory Network. In spite of this, however, surveillance
remains weak in many countries, and only 81 (52%) of 157 countries that reported discarded
¶¶
cases achieved the sensitivity indicator target of two or more discarded measles and
rubella cases per 100,000 population.
Countries report the number of incident measles cases*** to WHO and UNICEF annually
using the Joint Reporting Form.
†††
During 2000–2016, the number of reported measles cases decreased 84%, from 853,479
in 2000 to 132,490 in 2016. From 2000 to 2016, annual measles incidence decreased
88%, from 145 cases per 1 million (2000) to 18 (2016), the lowest reported incidence
during this period; incidence then increased 567% to 120 per million in 2019, the
highest since 2001 (Table 1). The percentage of reporting countries with annual measles
incidence of <5 cases per 1 million population increased from 38% (64 of 169) in 2000
to 70% (125 of 179) in 2016, but then decreased to 46% (85 of 184) in 2019.
The number of measles cases increased 556% from 132,490 in 2016 to 869,770 in 2019,
the most reported cases since 1996. Since 2016, the number of reported measles cases
increased 1,606% in WHO’s African Region (AFR), 19,739% in the Region of the Americas
(AMR), 194% in the Eastern Mediterranean Region (EMR), 2,282% in the European Region
(EUR), 6% in the South-East Asia Region (SEAR), and 36% in the Western Pacific Region
(WPR). In 2019, nine (5%) of 184 reporting countries (Central African Republic, DRC,
Georgia, Kazakhstan, Madagascar, North Macedonia, Samoa, Tonga, and Ukraine) experienced
large outbreaks, and in each of these countries, reported measles incidence exceeded
500 per 1 million population; these nine countries accounted for 631,847 (73%) of
all reported cases worldwide during 2019.
Genotypes of viruses isolated from persons with measles were reported by 88 (62%)
of 141 countries reporting at least one measles case in 2019. From 2005 to 2019, 20
of 24 recognized measles genotypes were eliminated by immunization activities. The
number of genotypes detected decreased from 11 during 2005–2008, to eight during 2009–2014,
six in 2016, five in 2017, and four during 2018–2019 (
3
). In 2019, among 8,728 reported sequences, 1,920 (22%) were genotype B3; six (0.1%)
were D4; 6,774 (78%) were D8; and 28 (0.3%) were H1.
§§§
Measles Case and Mortality Estimates
A previously described model for estimating measles cases and deaths (
4
) was updated with annual vaccination coverage data, case data, and United Nations
population estimates for all countries during 2000–2019, enabling derivation of a
new series of disease and mortality estimates. For countries with anomalous estimates
(e.g., a decrease in reported cases, but an increase in estimated deaths, or vice
versa), the model was modified slightly to generate mortality estimates consistent
with observed cases. Based on updated annual data, the estimated number of measles
cases decreased 65%, from 28,340,700 in 2000 to 9,828,400 in 2019. During this period,
estimated annual measles deaths decreased 62%, from 539,000 to 207,500 (Table 2).
During 2000–2019, compared with no measles vaccination, measles vaccination prevented
an estimated 25.5 million deaths globally (Figure).
TABLE 2
Estimated number of measles cases and deaths,* by World Health Organization (WHO)
region — worldwide, 2000 and 2019
WHO region/Year (no. of countries in region)
Estimated no. of measles cases (95% CI)
Estimated no. of measles deaths (95% CI)
Estimated % measles mortality reduction from 2000 to 2019
Cumulative no. of measles deaths averted by vaccination, 2000–2019
African
2000 (46)
10,727,500 (7,417,700–17,448,900)
346,400 (227,600–569,000)
57
13,620,000
2019 (47)
4,548,000 (3,266,700–8,376,100)
147,900 (99,500–271,100)
Americas
2000 (35)
8,800 (4,400–35,000)
NA†
NA
102,500
2019 (35)
102,700 (51,400–411,000)
NA†
Eastern Mediterranean
2000 (21)
2,565,800 (1,534,500–4,774,400)
40,000 (22,200–69,200)
33
2,877,900
2019 (21)
1,384,500 (717,900–3,201,000)
27,000 (14,700–49,500)
European
2000 (52)
816,600 (216,900–5,116,000)
350 (100–1,900)
66
101,300
2019 (53)
494,600 (192,800–6,571,400)
120 (20–1,700)
South-East Asia
2000 (10)
11,379,100 (8,937,200–15,299,200)
141,400 (102,000–194,600)
80
7,387,800
2019 (11)
2,655,000 (902,200–6,886,500)
28,700 (8,400–75,400)
Western Pacific
2000 (27)
2,843,000 (1,934,700–22,297,700)
10,900 (5,200–77,300)
65
1,385,500
2019 (27)
643,700 (127,600–18,007,600)
3,800 (500–75,100)
Totals
2000 (191)
28,340,700 (20,045,300–64,971,300)
539,000 (357,200–911,900)
62
25,475,000
2019 (194)
9,828,400 (5,258,500–43,453,500)
207,500 (123,100–472,900)
Abbreviations: CI = confidence interval; NA = not applicable; UNICEF = United Nations
Children’s Fund.
* The measles mortality model used to generate estimated measles cases and deaths
is rerun each year using the new and revised annual WHO/UNICEF estimates of national
immunization coverage (WUENIC) data, as well as updated surveillance data; therefore,
the estimated number of cases and mortality estimates in this report might differ
slightly from those in previous reports.
† Estimated measles mortality was too low to allow reliable measurement of mortality
reduction.
Regional Verification of Measles Elimination
By the end of 2019, no WHO region had achieved and maintained measles elimination;
83 (43%) individual countries had been verified by independent regional commissions
as having achieved or maintained measles elimination. The two countries verified in
2019 to have achieved elimination were Iran and Sri Lanka. No AFR country has yet
been verified as having eliminated measles. The AMR had achieved verification of measles
elimination in 2016; however, endemic measles transmission was reestablished in Venezuela
in 2018 and in Brazil in 2019.
Discussion
Despite substantial decreasing global measles incidence and measles-associated mortality
during 2000–2016, the global measles resurgence that commenced during 2017–2018 continued
in 2019 and marked a significant step backward in progress toward global measles elimination.
Compared with the historic low in reported cases in 2016, reported measles cases increased
556% in 2019, with increases in numbers of reported cases and incidence in all WHO
regions. Estimated global measles mortality increased nearly 50% since 2016. In all
WHO regions, the fundamental cause of the resurgence was a failure to vaccinate, both
in recent and past years, causing immunity gaps in both younger and some older age
groups. Lessons can be learned from outbreaks in various countries, as well as from
notable successes in countries such as China, Colombia, and India (
5
–
7
). Identifying and addressing gaps in population immunity will require additional
strategies as outlined in the Immunization Agenda 2030
¶¶¶
and the Measles-Rubella Strategic Framework 2021–2030 (
8
).
In 2019, the global increase in cases was driven by large outbreaks in several countries.
Huge outbreaks occurred in DRC and Madagascar during 2018–2019 as a consequence of
accumulations of large numbers of measles-susceptible children, which resulted from
longstanding extremely low MCV1 coverage, no introduction of MCV2 into the immunization
program, and suboptimal SIA implementation. Samoa’s outbreak resulted from a steady
decline in MCV1 and MCV2 coverage during 2014–2018, exacerbated by a decline in vaccine
confidence after two infant deaths occurred from an error in measles-mumps-rubella
vaccine administration (
9
). Ukraine’s outbreak was the result of low vaccine confidence among health care professionals,
low demand from the public, and challenges with vaccine supply, storage, and handling.****
Brazil’s outbreak was caused by previously unidentified immunity gaps, revealed by
sustained transmission following multiple measles virus importations from the outbreak
in neighboring Venezuela.
††††
Outbreaks must be investigated to understand whether and why communities were missed
by vaccination, so that immunization services can be strengthened to close population
immunity gaps. Where low vaccination coverage exists in specific populations, assessment
of behavioral and social drivers of low coverage is needed to inform the design and
implementation of targeted strategies, whether related to practical factors such as
limited access to services, or to social influences that affect confidence and motivation
to receive vaccination. Programs need to work to achieve and sustain the trust of
parents and communities to ensure understanding that receipt of vaccination is in
their children’s best interests. Programs should always be well prepared to respond
to any vaccine-related adverse event in a timely and effective manner to obviate fears
and hesitancy that can erode progress.
The findings in this report are subject to at least three limitations. First, large
differences between estimated and reported incidence indicate overall low surveillance
sensitivity, making comparisons between regions difficult to interpret. Second, some
countries have multiple measles surveillance systems and choose which data to submit
to WHO. In 2019, for example, Chad reported 1,882 cases to WHO from one surveillance
system, but another surveillance system identified 26,623 suspected measles cases.
Finally, the measles mortality model estimates might be biased upward or downward
by inaccurate model inputs, including vaccination coverage and surveillance data.
In 2020, the coronavirus disease 2019 pandemic has produced increased programmatic
challenges, leading to fewer children receiving vaccinations and poorer surveillance
(
10
). Progress toward measles elimination during and after the pandemic will require
strategies to integrate catch-up vaccination policies into essential immunization
services, assurance of safe provision of services, engagement with communities to
regain trust and confidence in the health system, and rapid outbreak response.
As outlined in the Immunization Agenda 2030, a global immunization strategy for 2021–2030,
further progress toward achieving measles elimination goals will require strengthening
essential immunization systems to increase 2-dose coverage, identify and close historical
immunity gaps through catch-up vaccination to prevent outbreaks, improve surveillance
and preparedness for rapidly responding to outbreaks, and leverage measles as a tracer
and guide to improving immunization programs (
8
).
Summary
What is already known about this topic?
All six World Health Organization (WHO) regions have a measles elimination goal.
What is added by this report?
During 2000–2016, annual reported measles incidence decreased globally; however, measles
incidence increased in all regions during 2017–2019. Since 2000, estimated measles
deaths decreased 62% and measles vaccination has prevented an estimated 25.5 million
deaths worldwide. No WHO region has achieved and maintained measles elimination.
What are the implications for public health practice?
To achieve regional measles elimination goals, additional strategies are needed to
help countries strengthen routine immunization systems, identify and close immunity
gaps, and improve case-based surveillance.
FIGURE
Estimated number of annual measles deaths with vaccination and in the absence of vaccination
— worldwide, 2000–2019*
* Deaths prevented by vaccination are estimated by the area between estimated deaths
with vaccination and those without vaccination (cumulative total of 25.5 million deaths
prevented during 2000–2019). Vertical bars represent upper and lower 95% confidence
intervals around the point estimate.
The figure is a line graph showing the estimated number of annual measles deaths worldwide,
during 2000–2019, with and without vaccination.