Are the Objectives Proposed by the WHO for Routine Measles Vaccination Coverage and Population Measles Immunity Sufficient to Achieve Measles Elimination from Europe?

Abstract

Background: The World Health Organization (WHO) proposed two-dose measles vaccination coverage of at least 95% of the population and percentages of measles immunity in the population of 85%−95% in order to achieve measles elimination in Europe. The objectives of this study were: (1) to determine the measles vaccination coverage required to establish herd immunity against measles viruses with basic reproduction numbers (Ro) ranging from 6 to 60, and (2) to assess whether the objectives proposed by the WHO are sufficient to establish herd immunity against measles viruses. Methods: The herd immunity effects of the recommended objectives were assessed by considering the prevalence of protected individuals required to establish herd immunity against measles viruses with Ro values ranging from 6 to 60. Results: The study found that percentages of two-dose measles vaccination coverage from 88% to 100% could establish herd immunity against measles viruses with Ro from 6 to 19, assuming 95% measles vaccination effectiveness. The study found that the objective of 95% for two-dose measles vaccination coverage proposed by the WHO would not be sufficient to establish herd immunity against measles viruses with Ro ≥ 10, assuming 95% measles vaccination effectiveness. By contrast, a 97% measles vaccination coverage objective was sufficient to establish herd immunity against measles viruses, with Ro values from 6 to 13. Measles immunity levels recommended in individuals aged 1−4 years (≥85%) and 5−9 years (≥90%) might not be sufficient to establish herd immunity against most measles viruses, while those recommended in individuals aged 10 or more years (≥95%) could be sufficient to establish herd immunity against measles viruses with Ro values from 6 to 20. Conclusion: To meet the goal of measles elimination in Europe, it is necessary to achieve percentages of two-dose measles vaccination coverage of at least 97%, and measles immunity levels in children aged 1−9 years of at least 95%.

Vaccination Coverage for Routine Vaccines and Herd Immunity Levels against Measles and Pertussis in the World in 2019

“…Measles vaccination with the two-dose measles vaccine can reduce measles incidence by direct and indirect protection in the target vaccination population and by indirect herd immunity protection in other population groups. Another study found that to meet the goal of measles elimination in Europe, it is necessary to achieve percentages of two-dose measles vaccination coverage of at least 97% [ 20 ].…”

“…The mean percentages of vaccination coverage with one and two doses of measles vaccine and one, two, and three doses of DTP vaccine in different regions of WHO were determined from the vaccination coverage with one and two doses of measles vaccine and one, two, and three doses of DTP vaccine in countries of the region (phase 2 of the analysis). Routine measles vaccination is based on two doses of a measles-containing vaccine (measles-rubella-mumps (MMR) vaccine) administered at 12–15 months (MCV1) and 3 years of age (MCV2) [ 13 , 20 , 21 ]. The percentages of vaccination coverage with MCV1 and MCV2 reported by different countries to the WHO–UNICEF global and regional immunization information system are provided for the nationally recommended age [ 18 ].…”

“…The indicator based on the vaccination coverage with two doses of measles vaccine has been determined in other studies [ 20 , 23 ]. Indicators based on the vaccination coverage with DTP1 and DTP3 vaccines were considered in other studies [ 19 ].…”

“…Anderson and May found values of R o ranging from 12 to 18 for measles and from 10 to 18 for pertussis in the review carried out in 1991 [ 30 ]. A recent study found values of R o of up to 45 for measles viruses [ 20 , 31 ].…”

Humoral Immunity against Measles in Mother–Infant Pairs during the First Year of Life in Greece: A Cross-Sectional Study

“…In 2015 the Hellenic Centre for Disease Control and Prevention (HCDCP) informed the Greek physicians about the risk of an upcoming measles outbreak and urged them to increase the vaccination rate with MMR, targeting vaccine coverage of ≥95%. According to recently published data [ 17 ], to eliminate measles in Europe, it is necessary to succeed percentages of complete vaccination coverage of at least 97% and measles immunity levels in children aged 1−9 years of at least 95%. In Greece, the percentage of one dose vaccine coverage with MMR in preschool children aged 2–3 years is deemed satisfactory, reaching 97.3% [ 18 ].…”