Write a short note on Measles-Containing Vaccine.

Definition

The measles-containing vaccine is a live attenuated vaccine given as MR (measles-rubella) in the UIP, or as MMR (measles-mumps-rubella), to protect against these diseases and support measles/rubella elimination.

Administration

• Two doses — the first at 9–12 months and the second at 16–24 months (Indian schedule).
• 0.5 mL subcutaneously; the two doses ensure protection in those who did not respond to the first.

Precautions & Aefis

• Being live, it is avoided in significant immunodeficiency and pregnancy.
• Minor AEFIs — fever and a mild rash 5–12 days later; rarely febrile seizures.

Indications & Catch-up

Any child who has missed the doses should receive catch-up MR/MMR; the vaccine is also used for outbreak control and post-exposure prophylaxis (within 72 hours of measles exposure).

Key Points Recap

• Live; two doses (9–12 and 16–24 months); subcutaneous; central to elimination.
• Avoid in pregnancy/immunodeficiency; can be used for post-exposure prophylaxis.

Programme Note

India has adopted measles-rubella (MR) vaccine campaigns and two routine doses to accelerate progress toward measles and rubella (and congenital rubella syndrome) elimination.

Exam Relevance

This is a frequently asked short note — remember the vaccine type/route, its place in the UIP schedule, and its key precautions or programmatic significance.

Two doses are needed for the ~95% coverage measles requires.

A Note on WHY We Give Two Doses

• A concept that explains a change in the schedule is understanding why one dose of measles vaccine is not enough — and why a second dose was added.
• It is not because immunity wanes.
• The measles vaccine produces durable, essentially lifelong immunity in those in whom it 'takes'.
• The problem is primary vaccine failure: roughly 10–15% of children who receive a single dose at 9 months fail to seroconvert at all — either because residual maternal antibody neutralised the vaccine, or because of an inadequate immune response or a cold-chain failure.
• Those children remain completely susceptible.
• Now recall that measles is extraordinarily infectious (R0 12–18), so herd immunity requires over 95% of the population to be immune.
• With a single dose achieving only 85–90% seroconversion, that threshold can never be reached — even with 100% coverage.
• Outbreaks are therefore inevitable.
• The second dose solves this: it is not a 'booster' but a second opportunity to seroconvert — and it captures the great majority of the primary failures, pushing population immunity above the threshold.