TABLE 1. Comparing and contrasting measles and rubella characteristics relevant to elimination.

Characteristic	Measles	Rubella
Infectivity	One of the most infectious viruses of humans	Variable according to population size, but moderate
Basic reproduction number (R0)	12–18 (10)	Median 5.2 (11)
Population immunity levels required to interrupt transmission	93%	Around 80%
Vaccine effectiveness (VE) of single dose	Depends strongly on age at first dose: 9 months 85% 12 months 93%	95%
VE of 2 doses	If MCV1 at 12 months, 97%	>95%
Coverage required to interrupt transmission	>95% two dose	Around 80% single dose
Waning immunity over time	None following infection, slow following two doses given at 12 months and older, potentially more rapid when MCV1 given earlier than 12 months	None observed
Requirements to elimination	Cannot eliminate with a single dose	Can eliminate with a single dose
Highest risk age group	Infants at highest risk of severe outcomes, followed by adults. Pregnant women are at higher risk of severe outcomes.	Developing fetus in first trimester
Critical community size to sustain transmission	250–400 000 (12)	1 million (13)
Strategy	Immunization programs aim to protect infants, boys and girls, through herd immunity. Direct protection of infants via early doses from 6 months is offered in high-risk settings.	Women of childbearing age are protected through herd immunity in countries where adult immunization campaigns have not been implemented. Some countries have adult catch-up strategies but women-only not recommended.

MCV1: measles-containing vaccine, first dose.

Source: Prepared by the authors.