Limits...
The potential for measles transmission in England.

Choi YH, Gay N, Fraser G, Ramsay M - BMC Public Health (2008)

Bottom Line: Maintaining elimination requires low susceptibility levels to keep the effective reproduction number R below 1.Since 1995, however, MMR coverage in two year old children has decreased by more than 10%.The effective reproduction numbers for each district and strategic health authority were calculated and possible outbreak sizes estimated.

View Article: PubMed Central - HTML - PubMed

Affiliation: Centre for Infections, Health Protection Agency, Colindale, NW9 5EQ, London. yoon.choi@hpa.org.uk

ABSTRACT

Background: Since the schools vaccination campaign in 1994, measles has been eliminated from England. Maintaining elimination requires low susceptibility levels to keep the effective reproduction number R below 1. Since 1995, however, MMR coverage in two year old children has decreased by more than 10%.

Methods: Quarterly MMR coverage data for children aged two and five years resident in each district health authority in England were used to estimate susceptibility to measles by age. The effective reproduction numbers for each district and strategic health authority were calculated and possible outbreak sizes estimated.

Results: In 2004/05, about 1.9 million school children and 300,000 pre-school children were recorded as incompletely vaccinated against measles in England, including more than 800,000 children completely unvaccinated. Based on this, approximately 1.3 million children aged 2-17 years were susceptible to measles. In 14 of the 99 districts, the level of susceptibility is sufficiently high for R to exceed 1, indicating the potential for sustained measles transmission. Eleven of these districts are in London. Our model suggests that the potential exists for an outbreak of up to 100,000 cases. These results are sensitive to the accuracy of reported vaccination coverage data.

Conclusion: Our analysis identified several districts with the potential for sustaining measles transmission. Many London areas remain at high risk even allowing for considerable under-reporting of coverage. Primary care trusts should ensure that accurate systems are in place to identify unimmunised children and to offer catch-up immunisation for those not up to date for MMR.

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Related in: MedlinePlus

Calculated proportion susceptible to measles, 2004/5 by age and vaccination status: a) England, b) London.
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Figure 3: Calculated proportion susceptible to measles, 2004/5 by age and vaccination status: a) England, b) London.

Mentions: Figure 3 shows the susceptibility of each school year cohort in England (all districts combined) calculated from the cleaned routine data and using estimates of vaccine efficacy. The overall proportion susceptible was 27% among 2–4 year olds (born 2000–2002), 13% among children among primary school children (5–10 year olds) and 9% among secondary school children. However there was considerable variation between districts ranging from 19% – 46% and 4% – 27% in 2–4 and 5–10 year olds respectively. The majority of susceptible children are completely unvaccinated with MMR: of susceptible primary school children, 74% have received 0 doses, 23% a single dose, and 3% two doses.


The potential for measles transmission in England.

Choi YH, Gay N, Fraser G, Ramsay M - BMC Public Health (2008)

Calculated proportion susceptible to measles, 2004/5 by age and vaccination status: a) England, b) London.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2563003&req=5

Figure 3: Calculated proportion susceptible to measles, 2004/5 by age and vaccination status: a) England, b) London.
Mentions: Figure 3 shows the susceptibility of each school year cohort in England (all districts combined) calculated from the cleaned routine data and using estimates of vaccine efficacy. The overall proportion susceptible was 27% among 2–4 year olds (born 2000–2002), 13% among children among primary school children (5–10 year olds) and 9% among secondary school children. However there was considerable variation between districts ranging from 19% – 46% and 4% – 27% in 2–4 and 5–10 year olds respectively. The majority of susceptible children are completely unvaccinated with MMR: of susceptible primary school children, 74% have received 0 doses, 23% a single dose, and 3% two doses.

Bottom Line: Maintaining elimination requires low susceptibility levels to keep the effective reproduction number R below 1.Since 1995, however, MMR coverage in two year old children has decreased by more than 10%.The effective reproduction numbers for each district and strategic health authority were calculated and possible outbreak sizes estimated.

View Article: PubMed Central - HTML - PubMed

Affiliation: Centre for Infections, Health Protection Agency, Colindale, NW9 5EQ, London. yoon.choi@hpa.org.uk

ABSTRACT

Background: Since the schools vaccination campaign in 1994, measles has been eliminated from England. Maintaining elimination requires low susceptibility levels to keep the effective reproduction number R below 1. Since 1995, however, MMR coverage in two year old children has decreased by more than 10%.

Methods: Quarterly MMR coverage data for children aged two and five years resident in each district health authority in England were used to estimate susceptibility to measles by age. The effective reproduction numbers for each district and strategic health authority were calculated and possible outbreak sizes estimated.

Results: In 2004/05, about 1.9 million school children and 300,000 pre-school children were recorded as incompletely vaccinated against measles in England, including more than 800,000 children completely unvaccinated. Based on this, approximately 1.3 million children aged 2-17 years were susceptible to measles. In 14 of the 99 districts, the level of susceptibility is sufficiently high for R to exceed 1, indicating the potential for sustained measles transmission. Eleven of these districts are in London. Our model suggests that the potential exists for an outbreak of up to 100,000 cases. These results are sensitive to the accuracy of reported vaccination coverage data.

Conclusion: Our analysis identified several districts with the potential for sustaining measles transmission. Many London areas remain at high risk even allowing for considerable under-reporting of coverage. Primary care trusts should ensure that accurate systems are in place to identify unimmunised children and to offer catch-up immunisation for those not up to date for MMR.

Show MeSH
Related in: MedlinePlus