MR/MMR Vaccine in Measles Control: A Case of Missed Opportunity?

Sir,

Susceptibility to rubella has been found to be high among adolescent girls in India. Studies conducted in Amritsar, Maharashtra, and Jammu report rubella susceptibility to be 36%, 23.6%, and 32.7% in pre-pubertal girls, adolescent females, and girls of 11-18 years respectively.(123)

It has been observed that around 40-45% of women in the childbearing age are susceptible to Rubella.(4) A study conducted in Amritsar reported that susceptibility among various age groups was 30.8% in 16-25 years, 22.8% in 26-35 years, and 40.7% in 36-45 years.(1) A study by Chandy et al., revealed 12.5% women of child bearing age were susceptible to rubella.(5)

Rubella infection in women during early pregnancy is associated with congenital rubella syndrome (CRS).(6) Different studies, involving laboratory (serological) confirmation of CRS among symptomatic children, have reported the CRS occurrence of 4.2%, 10.27%, and 40%.(789) The Union health ministry estimates the number of abnormal children being born annually because of rubella, to be around 30,000.(10)

Furthermore, estimates suggest a wide range of the lifetime cost of treating a single CRS case, with some exceeding US$ 75, 000 (INR 40,59,000).(6)

Thus, the aim of rubella vaccination is to prevent women from acquiring rubella during their pregnancy. There are two general approaches for the use of rubella vaccine:

First approach focuses exclusively on reducing CRS by immunizing adolescent girls and/or women of childbearing age;

Second approach aims at interrupting viral transmission and thereby eliminating rubella as well as CRS.(11)

In case of measles (M), providing a second opportunity for immunization to appropriate age groups of children through either a second routine dose of measles vaccine or through supplemental immunization activities (SIA) is one of the key strategies to achieve the goal of measles mortality reduction in India.

Measles-vaccine delivery strategies provide an opportunity for synergy and a platform for advancing rubella and CRS elimination. As per WHO, all countries that are providing two doses of measles vaccine using routine immunization or SIAs, or both, should consider including RCVs (Rubella containing vaccines) in their immunization programme.(11)

In India, switching from M to MR (Measles and Rubella) or MMR (Measles, Mumps and Rubella) vaccine may be viewed under following deliberations:

The exact Rubella disease load in the community cannot be made out clinically as more than half of all cases are subclinical. This makes the estimation, of those who are susceptible to the infection and hence at risk of having acute infection during pregnancy resulting in foetal CRS, difficult.(12)

Rubella vaccine is still not a part of national immunization schedule.

When the MR or MMR vaccines are used, the protective immune response to each of the components remains unchanged.(13)

One dose of rubella vaccine probably induces life-long protection.(11)

Large births cohort may miss the advantage, as the vaccine inclusion is delayed.

Switching from M to MR or MMR vaccine needs following considerations:

Achieving and maintaining measles vaccination coverage of 80% or greater through routine and/or regular campaigns before including immunization against rubella, as recommended by WHO.

Ensure availability of appropriate infrastructure and resources for immunization programmes.

Achieving ability to conduct high quality campaigns to close the rubella immunity gap at the time of introduction.

Improved record keeping is a strategic prerequisite to improve monitoring of progress towards coverage targets.

Ensuring vaccine security (reliable supply of quality vaccine at an affordable price) through strong engagement with industry and partners, as well as accurate forecasting of vaccine supplies as changing from M vaccine to a combined MR vaccine increases the cost per dose by about INR 16.24 for MR vaccine and by INR 37.89-INR 51.42 for MMR vaccine based on using 10-dose vials.(6)

A concerned and concentrated effort is required by all the sectors and agencies involved so that the delay in the inclusion of MR/MMR vaccine may not turn out to be a “missed opportunity” as in Immunisation parlance.