Progress Toward Regional Measles Elimination — Worldwide, 2000–2021

Anna A. Minta, MD; Matt Ferrari, PhD; Sebastien Antoni, MPH; Allison Portnoy, ScD; Alyssa Sbarra, MPH; Brian Lambert; Sarah Hauryski; Cynthia Hatcher, MPH; Yoann Nedelec, MPH; Deblina Datta, MD; Lee Lee Ho, MPH; Claudia Steulet, MPH; Marta Gacic-Dobo, MSc; Paul A. Rota, PhD; Mick N. Mulders, PhD; Anindya S. Bose, MD; William A. Perea; Patrick O'Connor, MD

Disclosures

Morbidity and Mortality Weekly Report. 2022;71(47):1489-1495.

Immunization Activities

WHO and UNICEF use data from 1) administrative coverage (calculated by dividing the number of vaccine doses administered by the estimated target population reported annually), 2) country estimates,^¶ and 3) vaccination coverage surveys to estimate MCV1 and second dose MCV (MCV2) coverage through routine immunization services (i.e., not mass campaigns).** During 2000–2010, estimated MCV1 coverage increased worldwide from 72% to 84%. However, coverage stagnated at 84% to 86% during 2010–2019, decreased to 83% in 2020 during the COVID-19 pandemic, and further declined to 81% in 2021. Although regional variation exists, all six WHO regions reported a decline in MCV1 coverage since 2019, with only the European Region plateauing from 2020 to 2021 (Table 1).

Among 194 WHO member states, 91 (47%) achieved ≥90% MCV1 coverage in 2021; however, among these countries, only 24 (26%) reported MCV1 coverage of ≥80% in all districts. In 2021, 24.7 million infants did not receive MCV1 through routine immunization services, an increase of 2.4 million (11%) from 2020. The 10 countries with the highest number of infants who did not receive MCV1 were Nigeria (3.1 million), India (2.5 million), Democratic Republic of the Congo (1.7 million), Ethiopia (1.7 million), Indonesia (1.2 million), Pakistan (1.2 million), Philippines (1.0 million), Angola (0.8 million), Brazil (0.7 million), and Tanzania (0.5 million). These countries accounted for 59% of all children who did not receive MCV1. Estimated MCV2 coverage quadrupled from 17% in 2000 to 72% in 2020, then declined slightly, to 71% in 2021. The number of countries offering MCV2 increased by 92%, from 95 (50%) in 2000 to 182 (94%) in 2021. Three countries (Comoros, Côte d'Ivoire, and Equatorial Guinea) introduced MCV2 in 2021.^††

Approximately 150 million persons received MCV during supplementary immunization activities (SIAs)^§§ in 18 countries in 2021. An additional 4 million persons received MCV during measles outbreak response activities. As of December 2021, 25 MCV campaigns that had been postponed since the start of the COVID-19 pandemic had been conducted; however, 18 MCV campaigns planned since March 2020 had still not been conducted, which resulted in an estimated 61 million postponed or missed MCV doses.

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Abstract and Introduction
Immunization Activities
Surveillance Performance and Reported Measles Incidence
Measles Case and Mortality Estimates
Regional Verification of Measles Elimination
Discussion
References
Sidebar

^¶Estimates based on administrative data as well as any other available information on factors affecting immunization coverage, including private or nongovernmental organization sector contributions to immunization, difficulties with demographic data, and incomplete reporting.
**Calculated for MCV1, among children aged 1 year or, if MCV1 is administered at age ≥1 year, among children aged 24 months. Calculated for MCV2 among children at the recommended age for the administration of MCV2 per the national immunization schedule. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8464208/
^††Data as of September 20, 2022. https://immunizationdata.who.int/pages/vaccine-intro-by-antigen/mcv2.html?ISO_3_CODE=&YEAR=
^§§SIAs are typically carried out using two target age ranges: 1) an initial catch-up SIA focuses on infants, children, and adolescents aged 9 months–14 years to eliminate susceptibility to measles in a population, and 2) periodic follow-up SIAs then focus on infants and children aged 9–59 months born since the last SIA. Follow-up SIAs typically are conducted nationwide every 2–4 years to eliminate measles susceptibility in recent birth cohorts because of low MCV coverage and to protect infants, children, and adolescents who did not respond to MCV1. Countries can provide additional data to WHO, and data are updated retrospectively. https://immunizationdata.who.int/listing.html?topic=&location=

Table 1. Estimates of regional immunization coverage with the first and second doses of measles-containing vaccine administered through routine immunization services, reported measles cases, and measles incidence, by World Health Organization region — worldwide, 2000–2021
Yr/WHO region (no. of countries in region)	Percentage				No. of reported measles cases^§ (% of total cases)	Measles incidence^§,¶,**
Yr/WHO region (no. of countries in region)	MCV1* coverage	Countries with ≥90% MCV1 coverage^†	MCV2* coverage	Reporting countries with <5 measles cases per 1 million population^§,¶	No. of reported measles cases^§ (% of total cases)	Measles incidence^§,¶,**
Total (all regions)
2000 (191)	72	44	17	33	853,479 (100)	145
2010 (193)	84	63	42	59	343,806 (100)	50
2016 (194)	85	61	67	64	132,490 (100)	18
2019 (194)	86	62	71	44	873,022 (100)	120
2020 (194)	83	51	72	57	159,073 (100)	21
2021 (194)	81	47	71	66	123,981 (100)	17
African
2000 (46)	53	9	5	6	520,102 (60.9)	832
2010 (46)	72	36	5	30	199,174 (57.9)	232
2016 (47)	68	34	22	49	36,269 (27.4)	37
2019 (47)	70	30	33	34	618,595 (70.9)	560
2020 (47)	69	19	40	30	115,369 (72.5)	106
2021 (47)	68	23	41	34	89,602 (72.3)	83
Americas
2000 (35)	93	63	65	89	1,754 (0.2)	2
2010 (35)	93	74	67	100	247 (0.1)	0.3
2016 (35)	92	66	80	97	97 (0.1)	0.1
2019 (35)	87	69	72	89	21,971 (2.5)	32
2020 (35)	85	43	72	97	9,996 (6.3)	10
2021 (35)	84	31	75	97	682 (0.6)	0.7
Eastern Mediterranean
2000 (21)	71	57	27	14	38,592 (4.5)	87
2010 (21)	76	62	52	38	10,072 (2.9)	17
2016 (21)	82	57	73	52	6,275 (4.7)	10
2019 (21)	83	52	76	38	18,458 (2.1)	26
2020 (21)	83	48	77	48	6,769 (4.3)	10
2021 (21)	82	48	77	52	26,089 (21.0)	40
European
2000 (52)	91	60	48	38	37,421 (4.4)	50
2010 (53)	94	83	80	68	30,625 (8.9)	34
2016 (53)	93	81	88	77	4,440 (3.4)	5
2019 (53)	96	85	92	30	106,130 (12.2)	117
2020 (53)	94	77	91	70	10,945 (6.9)	14
2021 (53)	94	70	91	91	99 (0.1)	0.1
South-East Asia
2000 (10)	62	27	3	0	78,558 (9.2)	51
2010 (11)	83	45	15	36	54,228 (15.8)	30
2016 (11)	89	64	75	27	27,530 (20.8)	14
2019 (11)	94	73	83	27	29,389 (3.4)	15
2020 (11)	88	64	80	45	9,389 (5.9)	5
2021 (11)	86	55	78	55	6,448 (5.2)	3
Western Pacific
2000 (27)	85	48	2	26	177,052 (20.7)	106
2010 (27)	97	63	87	63	49,460 (14.4)	28
2016 (27)	96	63	93	48	57,879 (43.7)	31
2019 (27)	95	70	93	41	78,479 (9.0)	41
2020 (27)	94	63	94	37	6,605 (4.2)	4
2021 (27)	91	59	91	48	1,061 (0.9)	0.6

Abbreviations: MCV1 = first dose of measles-containing vaccine; MCV2 = second dose of measles-containing vaccine; WHO = World Health Organization.
*https://immunizationdata.who.int/pages/coverage/mcv.html (Accessed September 29, 2022).
^†Denominator is the number of WHO member states.
^§https://immunizationdata.who.int/pages/incidence/measles.html (Accessed September 29, 2022).
^¶Population data from United Nations Department of Economic and Social Affairs, Population Division, 2022. Any country not reporting measles cases for that year was removed from both the numerator and denominator in calculating incidence.
**Cases per 1 million population.

Table 2. Estimated number of measles cases and deaths,* by World Health Organization region — worldwide, 2000 and 2021
Yr/WHO region (no. of countries in region)	No. (95% CI)		Estimated reduction in measles mortality, %2000–2021	Cumulative no. of measles deaths averted by vaccination2000–2021
Yr/WHO region (no. of countries in region)	Estimated no. of measles cases	Estimated no. of measles deaths	Estimated reduction in measles mortality, %2000–2021
Total, all regions
2000 (191)	34,012,634 (27,393,416–42,901,683)	761,038 (561,895–993,312)	83	55,812,741
2021 (194)	9,484,464 (5,681,867–14,881,517)	127,656 (74,444–197,500)	83	55,812,741
African
2000 (46)	10,965,152 (7,134,948–14,649,839)	356,299 (227,304–488,539)	81	19,499,793
2021 (47)	4,430,595 (2,619,358–7,030,815)	66,229 (38,811–106,293)	81	19,499,793
Americas
2000 (35)	8,770 (4,385–35,080)	NA^†	61	4,343,128
2021 (35)	3,410 (1,705–13,640)	NA^†	61	4,343,128
Eastern Mediterranean
2000 (21)	4,370,190 (3,295,576–6,213,952)	150,299 (115,962–205,857)	67	9,553,930
2021 (21)	2,303,170 (1,304,581–3,075,854)	48,979 (26,638–72,045)	67	9,553,930
European
2000 (52)	911,710 (733,732–1,353,344)	3,869 (3,098–4,747)	97	1,146,475
2021 (53)	86,196 (25,252–208,956)	132 (34–352)	97	1,146,475
South-East Asia
2000 (10)	12,395,953 (11,108,235–14,268,354)	224,822 (192,623–266,165)	95	16,546,297
2021 (11)	1,702,699 (1,399,591–2,321,389)	10,230 (8,328–13,538)	95	16,546,297
Western Pacific
2000 (27)	5,360,859 (5,116,541–6,381,114)	25,746 (22,907–27,993)	92	4,723,119
2021 (27)	958,395 (331381–2,230,863)	2,085 (633–5,267)	92	4,723,119

Abbreviations: NA = not applicable; WHO = World Health Organization.
*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 data as well as updated surveillance data. In 2021, data on case fatality from an updated systematic review and a suite of covariates with known relationships to case fatality were used in a Bayesian meta-regression modeling framework to produce estimates of measles case fatality ratios; therefore, the estimated number of cases and mortality estimates for 2000–2020 in this report differs from previous reports.
^†Estimated measles mortality was too low to allow reliable measurement of mortality reduction.