What is the importance of Measles (Measles Virus) and Rubella (German Measles) supplemental immunization?

Measles-Rubella Supplemental Immunization: Critical for Disease Elimination and Prevention of Devastating Birth Defects

Supplemental measles-rubella immunization activities are essential to achieve and maintain population immunity levels above 95%, interrupt endemic transmission, rapidly control outbreaks, and prevent congenital rubella syndrome—a devastating condition causing deafness, cardiac defects, cataracts, and mental retardation in up to 85% of first-trimester infections. 1

Primary Goals of Supplemental Immunization Activities

Supplemental immunization campaigns serve distinct purposes beyond routine vaccination programs:

• Closing immunity gaps in populations where routine coverage has been suboptimal, particularly targeting susceptible adults and specific age cohorts who may have missed routine doses 2
• Achieving the 95% coverage threshold required for herd immunity and disease elimination, which routine services alone often fail to reach 3, 4
• Rapid outbreak control by vaccinating all at-risk persons in affected settings within 72 hours of case identification, regardless of prior vaccination status 2

Prevention of Congenital Rubella Syndrome

The most critical outcome of rubella supplemental immunization is preventing CRS:

• Rubella infection during pregnancy carries a ≥20% risk of causing CRS when infection occurs in the first trimester, compared to the 0-1.6% theoretical risk from inadvertent vaccination 2
• Postpartum vaccination programs targeting non-immune women could prevent approximately 40-50% of CRS cases, making hospital discharge vaccination a crucial supplemental strategy 2, 5
• Women of childbearing age require special focus in supplemental campaigns, particularly those born outside countries with routine rubella vaccination programs 1

Outbreak Response and Rapid Vaccination

Supplemental immunization becomes mandatory during outbreaks:

• Mandatory exclusion policies combined with rapid vaccination of all persons lacking documented immunity effectively terminates outbreaks in schools, workplaces, and healthcare settings 2
• Healthcare settings require aggressive supplemental vaccination of all workers without documented immunity during rubella outbreaks, as transmission to pregnant patients poses catastrophic risks 2
• Measles postexposure prophylaxis within 72 hours can provide protection if administered as supplemental vaccination to exposed susceptible persons 2

Target Populations for Supplemental Activities

High-Risk Groups Requiring Supplemental Doses

• Healthcare workers of all ages, including those born before 1957, should receive supplemental MMR if they lack documented immunity, as 5-9% of pre-1957 birth cohorts lack measles antibody and 6% lack rubella antibody 2
• College students and young adults in congregate settings where outbreaks frequently occur require verification of two-dose measles vaccination and at least one rubella dose 2
• International travelers to endemic areas need supplemental doses if lacking documented immunity, with infants 6-11 months requiring early vaccination before departure 2
• Immigrant populations, particularly women from areas without routine rubella vaccination, require targeted supplemental campaigns 1

Evidence of Impact from Supplemental Campaigns

• Regional elimination success: In the WHO European Region, supplemental immunization activities reaching approximately 38 million persons in 20 countries during 2005-2019 contributed to a >99% decline in rubella incidence and 50% reduction in CRS cases 4
• Coverage gaps persist: Even after national campaigns, immunity levels may remain below elimination thresholds—Iran's campaign achieved only 72.7-87.5% measles immunity in some age groups, demonstrating the need for repeated supplemental activities 3

Implementation Strategy for Supplemental Activities

When Routine Coverage Fails

• Supplemental second-dose campaigns become necessary when routine services fail to achieve 95% coverage in every district, as demonstrated by ongoing measles transmission despite high national coverage rates 3, 4
• Age-cohort targeting addresses populations who grew up before two-dose schedules were implemented or in areas with historically low coverage 2

Outbreak Settings Requiring Immediate Action

• Exclude all susceptible persons from schools, workplaces, or healthcare facilities for 3 weeks after the last case's rash onset unless they receive supplemental vaccination 2
• Do not delay for serologic screening during outbreaks—rapid vaccination of all persons without documented immunity takes priority over cost-effectiveness considerations 2

Critical Pitfalls to Avoid

• Voluntary appeals are ineffective: Experience demonstrates that mandatory exclusion policies combined with required vaccination achieve outbreak control, while voluntary approaches fail 2
• Do not assume immunity in older adults: Healthcare facilities must vaccinate workers born before 1957 during outbreaks, as surveillance shows 27% of measles cases in healthcare workers occurred in this age group 2
• Never delay postpartum vaccination: Immediate vaccination before hospital discharge is essential, as delayed vaccination results in missed opportunities that could prevent 40% of future CRS cases 2, 5

Special Considerations for Supplemental Campaigns

• Breastfeeding is NOT a contraindication to postpartum supplemental vaccination, despite potential viral excretion in breast milk causing asymptomatic infant infection 2, 5
• Pregnancy must be avoided for 3 months after supplemental rubella vaccination, though inadvertent vaccination of 321 pregnant women resulted in zero cases of CRS 1
• Immunocompromised contacts can safely receive household exposure to vaccinated persons, as vaccine virus is not transmitted person-to-person 2