Progress towards elimination of measles in Kenya, 2003-2016

Kisangau, Ngina; Sergon, Kibet; Ibrahim, Yusuf; Yonga, Florence; Langat, Daniel; Nzunza, Rosemary; Borus, Peter; Galgalo, Tura; Lowther, Sara A.

doi:10.11604/pamj.2018.31.65.16309

Cited by 11 publications

(20 citation statements)

References 12 publications

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“…To compound difficulties in choosing the desired interval, delays to planned SIAs are not uncommon, e.g. due to delays in obtaining funding and logistical support, political changes, natural or man-made disasters [ 36 , 37 ]. Appropriate timing of SIAs is critical to immunize susceptible individuals before an increase in transmission occurs [ 29 ].…”

Section: Introductionmentioning

confidence: 99%

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Vaccination strategies for measles control and elimination: time to strengthen local initiatives

Cutts

Ferrari

Krause

et al. 2021

BMC Med

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Background Through a combination of strong routine immunization (RI), strategic supplemental immunization activities (SIA) and robust surveillance, numerous countries have been able to approach or achieve measles elimination. The fragility of these achievements has been shown, however, by the resurgence of measles since 2016. We describe trends in routine measles vaccine coverage at national and district level, SIA performance and demographic changes in the three regions with the highest measles burden. Findings WHO-UNICEF estimates of immunization coverage show that global coverage of the first dose of measles vaccine has stabilized at 85% from 2015 to 19. In 2000, 17 countries in the WHO African and Eastern Mediterranean regions had measles vaccine coverage below 50%, and although all increased coverage by 2019, at a median of 60%, it remained far below levels needed for elimination. Geospatial estimates show many low coverage districts across Africa and much of the Eastern Mediterranean and southeast Asian regions. A large proportion of children unvaccinated for MCV live in conflict-affected areas with remote rural areas and some urban areas also at risk. Countries with low RI coverage use SIAs frequently, yet the ideal timing and target age range for SIAs vary within countries, and the impact of SIAs has often been mitigated by delays or disruptions. SIAs have not been sufficient to achieve or sustain measles elimination in the countries with weakest routine systems. Demographic changes also affect measles transmission, and their variation between and within countries should be incorporated into strategic planning. Conclusions Rebuilding services after the COVID-19 pandemic provides a need and an opportunity to increase community engagement in planning and monitoring services. A broader suite of interventions is needed beyond SIAs. Improved methods for tracking coverage at the individual and community level are needed together with enhanced surveillance. Decision-making needs to be decentralized to develop locally-driven, sustainable strategies for measles control and elimination.

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Section: Introductionmentioning

confidence: 99%

“…Major outbreaks have been reported shortly before a scheduled follow-up SIA in e.g. Burkina Faso, DRC and Kenya [ 36 , 37 ] while delays in implementing outbreak response vaccination campaigns may allow widespread transmission to occur [ 38 ].…”

Section: Introductionmentioning

confidence: 99%

Vaccination strategies for measles control and elimination: time to strengthen local initiatives

Cutts

Ferrari

Krause

et al. 2021

BMC Med

View full text Add to dashboard Cite

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“…14 MCV2 was introduced into the RI programme in Kenya in 2013 and coverage rose to 45% in 2018 after introduction. 9 The last measles SIA in children aged 9 months to 14 years took place in 2016 and achieved 95% coverage. 15 We assumed national MCV1 and MCV2 coverage were 79% and 45% respectively in 2018, and that these stayed at the same level from August 2019 until the end of March 2020 when COVID-19 contact restrictions were introduced in Kenya.…”

Section: Vaccination Coveragementioning

confidence: 99%

The importance of supplementary immunisation activities to prevent measles outbreaks during the COVID-19 pandemic in Kenya

Mburu

Ojal

Chebet

et al. 2020

Preprint

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Background: The COVID-19 pandemic has disrupted routine measles immunisation and supplementary immunisation activities (SIAs) in most countries including Kenya. We assessed the risk of measles outbreaks during the COVID-19 pandemic in Kenya as a case study for the African Region. Methods: Combining measles serological data, local contact patterns, and vaccination coverage into a cohort model, we predicted the age-adjusted population immunity in Kenya and estimated the probability of outbreaks when contact-reducing COVID-19 interventions are lifted. We considered various scenarios for reduced measles vaccination coverage from April 2020. Findings: In February 2020, when a scheduled SIA was postponed, population immunity was close to the herd immunity threshold and the probability for one case to initiate a large outbreak as 22% (0-46). As restrictions to physical contact are lifted, from December 2020, the probability for a large outbreak increased to 31% (8-51), 35% (16-52) and 43% (31-56) assuming a 15%, 50% and 100% reduction in vaccination coverage. By December 2021, this risk is higher at 37% (17-54), 44% (29-57) and 57% (48-65) for the same coverage scenarios respectively. However, the increased risk of a measles outbreak following the lifting of the COVID-19 restrictions on contact can be overcome by conducting an SIA with ≥ 95% coverage in under-fives. Interpretation: While the reduction in measles transmissibility through COVID-19 restrictions temporarily reduced the risk from a measles immunity gap, this risk rises again rapidly once physical distancing is relaxed. Implementing delayed SIAs will be critical for prevention of measles outbreaks once contact restrictions are fully lifted in Kenya.

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“…Measles control in Kenya is achieved by giving children a first dose of measles-containing vaccine (MCV1) at 9 months, and a second dose (MCV2) from 18 months. SIAs, first introduced in 2002, are conducted periodically among children < 5 years or < 15 years for accelerated control of measles [ 9 ]. Based on the accumulation of susceptible children, the timing of such campaigns has typically been chosen to close immunity gaps in time to prevent potentially large measles outbreaks.…”

Section: Introductionmentioning

confidence: 99%

The importance of supplementary immunisation activities to prevent measles outbreaks during the COVID-19 pandemic in Kenya

Mburu

Ojal

Chebet

et al. 2021

BMC Med

View full text Add to dashboard Cite

Background The COVID-19 pandemic has disrupted routine measles immunisation and supplementary immunisation activities (SIAs) in most countries including Kenya. We assessed the risk of measles outbreaks during the pandemic in Kenya as a case study for the African Region. Methods Combining measles serological data, local contact patterns, and vaccination coverage into a cohort model, we predicted the age-adjusted population immunity in Kenya and estimated the probability of outbreaks when contact-reducing COVID-19 interventions are lifted. We considered various scenarios for reduced measles vaccination coverage from April 2020. Results In February 2020, when a scheduled SIA was postponed, population immunity was close to the herd immunity threshold and the probability of a large outbreak was 34% (8–54). As the COVID-19 contact restrictions are nearly fully eased, from December 2020, the probability of a large measles outbreak will increase to 38% (19–54), 46% (30–59), and 54% (43–64) assuming a 15%, 50%, and 100% reduction in measles vaccination coverage. By December 2021, this risk increases further to 43% (25–56), 54% (43–63), and 67% (59–72) for the same coverage scenarios respectively. However, the increased risk of a measles outbreak following the lifting of all restrictions can be overcome by conducting a SIA with ≥ 95% coverage in under-fives. Conclusion While contact restrictions sufficient for SAR-CoV-2 control temporarily reduce measles transmissibility and the risk of an outbreak from a measles immunity gap, this risk rises rapidly once these restrictions are lifted. Implementing delayed SIAs will be critical for prevention of measles outbreaks given the roll-back of contact restrictions in Kenya.

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Progress towards elimination of measles in Kenya, 2003-2016

Cited by 11 publications

References 12 publications

Vaccination strategies for measles control and elimination: time to strengthen local initiatives

Vaccination strategies for measles control and elimination: time to strengthen local initiatives

The importance of supplementary immunisation activities to prevent measles outbreaks during the COVID-19 pandemic in Kenya

The importance of supplementary immunisation activities to prevent measles outbreaks during the COVID-19 pandemic in Kenya

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