|Year : 2018 | Volume
| Issue : 1 | Page : 16-21
Effectiveness of a nationwide measles vaccination campaign in Libya, 2005: Retrospective study
Salem I M. Alkoshi1, Kacey C Ernst2
1 Department of Public Health, Medical Technology College, Elmergib University, Al Khoms, Libya
2 Department of Epidemiology and Biostatistics, Mel and Enid Zuckerman College of Public Health, The University of Arizona, Arizona, USA
|Date of Web Publication||27-Mar-2018|
Dr. Salem I M. Alkoshi
P O Box 504, Zliten City
Source of Support: None, Conflict of Interest: None
Background: Measles is a highly contagious virus. An effective vaccine has been widely administered for over three decades, but the measles burden is still high, causing 134,200 deaths globally in 2014. In Libya, a national mass measles vaccination campaign took place in 2005 targeting all residents of Libya age 9 months to 20 years between February 2005 5, and March 1, 2005. To date, no evaluation of its effectiveness has been conducted. Materials and Methods: Measles surveillance data were obtained for a 6 years' period (2002–2007) spanning the 3 years before and the 3 years following the mass vaccination campaign. The incidence of measles cases was calculated pre- and postvaccination campaigns and relative change in incidence was determined. Results: During the campaign 2,431,167 people age 9 months–20 years were vaccinated, resulting in a coverage rate of 98.4% in that age range. Comparing incidence of measles cases pre-and postvaccination campaign demonstrates an effectiveness of 96%, P = 0.021. Seasonality of measles cases was identified with a peak in April and May. Effectiveness varied by the age group, ranging from 82% in people lower than 5 years of age. Conclusion: A significant reduction was demonstrated following a national immunization campaign. Supplementary immunization campaigns should be initiated to keep the Libyan measles rate low; allowing the country to move into an elimination period.
Keywords: Campaign, efficacy, Libya, measles, vaccine
|How to cite this article:|
M. Alkoshi SI, Ernst KC. Effectiveness of a nationwide measles vaccination campaign in Libya, 2005: Retrospective study. Libyan J Med Sci 2018;2:16-21
|How to cite this URL:|
M. Alkoshi SI, Ernst KC. Effectiveness of a nationwide measles vaccination campaign in Libya, 2005: Retrospective study. Libyan J Med Sci [serial online] 2018 [cited 2018 Nov 16];2:16-21. Available from: http://www.ljmsonline.com/text.asp?2018/2/1/16/228679
| Introduction|| |
Measles is a highly contagious virus that remains a leading cause of death in young children worldwide.,, Before widespread of routine measles vaccine in 1980s, measles disease epidemic was occurred approximately every 2–3 years and caused an estimate of 2.6 million deaths each year.
The measles vaccine was licensed in 1960s, and is regarded as one of the most cost-effective intervention available. Two doses of measles vaccine are recommended to ensure immunity since about 15% of vaccinated children do not develop immunity from the first dose. Global coverage for the first dose of measles vaccine through routine immunization (RI) increased from 73% to 85% between 2000 and 2015.,, However, in 2015, measles still caused an estimated 134,000 deaths globally equaling 365 deaths in a day or 15 deaths per hour.,
Mortality rates and complications from measles are highest in unvaccinated young children, unvaccinated pregnant women, nonimmune people (unvaccinated or no seroconversion). Individuals living in countries with low per capita incomes with weak health-care infrastructure are disproportionately affected due to lack of appropriate treatment. High levels of transmission and mortality have been seen in overcrowded following a natural disaster or conflict that also damage health-care infrastructure. Although there is no specific antiviral treatment for measles, prescribing vitamin A twice a day to children diagnosed with measles in developing countries can help to prevent from eye damage and blindness. It is estimated that routine vitamin A supplements in healthy children could reduce half of the measles deaths.
In Libya, limited data exist on measles incidence before the National Center for Disease Control (NCDC) was established in 2001. The vaccine had been administrated for all children aged 9 and 18 months in the mid-1970s and updated to be in 12 and 18 months after the campaign in 2005. In 2005, a national measles vaccination campaign was conducted targeting people age 9 months–20 years using Measles and Rubella vaccine (MR). This followed a long gap since the last campaign and irregularity of the vaccine supply chain during the 1990s and high burden of measles disease especially among people below 20 years. During the campaign, 2,431,167 were vaccinated people; WHO calculated a coverage rate of 98.4% for MR in the campaign., This study aimed to determine the effectiveness of the national measles vaccination campaign to reduce the burden of measles among people in Libya.
| Materials and Methods|| |
This is a retrospective study to estimate the effectiveness of a national measles campaign on people.
The general population that record into the public health surveillance system in Libya. This includes Libyan and non-Libyan people living within the country.
Approximately 2,421,880 individuals age 9 months–20 years were targeted for vaccination during February 5, 2005–March 1, 2005. The campaign was funded and executed by NCDC which ensured continuity of the cold chain and provided all equipment, training for 6151 vaccinators, technical support, and vaccines for the campaign. The country was divided into 1565 vaccination sites. The number of vaccination sites was determined according to the density of population in each city and region. National campaign vaccination sites can be seen in [Figure 1].
Surveillance data from the Libyan National Centers for Disease Control were used to determine the number of measles cases diagnosed between 2002 and 2007. Before the measles campaign period, all measles cases were clinically diagnosed. Postcampaign all suspected measles cases were tested using the Enzygnost Anti-Measles Viruses/IgM test from SIEMENS industry supplied by the WHO.
Incidence rate (IR) of measles cases was calculated for each time periods, 2002–2004 and April 1, 2005–2007, to account for cases that may have occurred in the first part of 2005 before the campaign was initiated and during a 30-day window in which the vaccine would have been ineffective. Impact of the vaccine on measles transmission was determined by calculating the relative risk of measles cases in the Libyan population before and after the campaign.
IR0 = Number of cases of measles reported 2002–2004/population of Libya 2003
IR1 = Number of cases of measles reported 2005–2007/Population of Libya 2006
Relative decrease in cases was calculated = IR0–IR1.
IR for specific age group (e.g., <5) = Number of measles for ages <5/Population <5 years of age.
Population in Libya used to calculate the incidence in precampaign period was 5,240,658 for the year of 2003, while in postcampaign period the population used to calculate the incidence was 5,657,692 for the year of 2006.
This calculation was repeated for different age groups under 5, 5–9, 10–14, 15–19, 20–24, 25–29, 30–34, 35–39, 40–44, 45–49, and 50 and above.
Seasonality was examined by graphing incidence of measles cases by month over the 6 years' time period.
Software package for statistical analysis (SPSS) version 16, (International Business Machines Corporation (IBM), Armonk, New York, USA). was used to determine the comparison between the two stages (pre- and postcampaign). T-test was used to analyze the data for determining the significant difference between the two stages (pre- and postcampaign) and P value.
The consent to use measles data during the period between 2002 and 2007 was obtained from surveillance and response administration at NCDC.
| Results|| |
The campaign vaccinated 2,431,167 people aged between 9 months and 20 years based on NCDC which is the responsible of conducting the campaign. All vaccinated people were living in the country (Libyan and non-Libyan).
Measles cases in pre- and postcampaign
During prevaccination campaign stage, measles cases reported were 3865 cases in 2002, 2183 cases in 2003 and 2771 cases in 2004; for a total of 8,819 cases (incidence 1.68/1000 Libyan population) [Table 1]. Postvaccination campaign, the number of measles cases reported was 292 cases in 2005, 38 cases in 2006 and 59 cases in 2007; for a total of 389 cases (incidence 0.07/1000 Libyan population). A significant reduction of manifestations of measles cases was shown through 3 years of postcampaign by 96%, P = 0.021. IR for each year in the study can be seen in [Figure 2].
|Table 1: Number of measles cases reported and incidence rate during the period pre- (2002-2004) and post-campaign (April 1, 2005-2007)|
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|Figure 2: Incidence of Measles Cases per 1000 population between 2002 and 2007 in Libya|
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Distribution cases by months
During 3 years of prevaccination campaign, seasonal occurrence of measles cases was high from March to May, while it was low between October and December. In postvaccination campaign stage, the appearance of monthly measles cases was slightly different between months. It was high from January to March and low from September to December. The seasonal occurrence was unclearly appeared in months during postvaccination campaign [Figure 3] and [Table 2].
|Figure 3: Monthly distrbution of total number of cases in pre and post-campaign|
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Distribution cases by ages
Measles cases were reduced across all age groups [Table 3]. Most cases were seen at the age group of 10–25 years, which were in range 1283–1744 measles cases during precampaign. These cases were reduced in the range 75%–100%. The effectiveness of the vaccine for most age groups were more than 90% except the age group below 5 years and above 50 years which were 82% and 75%, respectively.
Distribution cases by districts
The effectiveness of the vaccine in each districts was more than 80%, and 96% was the total coverage of the country. However, five districts had a coverage rate <80% in which they did not meet the target of the campaign. The coverage rate of them was in the range of 56%–81% [Table 4]. The target of the campaign to take a place in elimination stage should be ≥90% nationwide and ≥80% in each district.
| Discussion|| |
A measles vaccination campaign in 2005 played a significant role in reducing the burden of measles cases in Libya. Overall, there was a 96% reduction in number of cases comparing post- to pre-campaign periods. Although measles vaccines were being provided through RI programs, coverage had faltered. To achieve the high vaccination coverage rate (98.4%) for the targeted age group from 9 months to 20 years  an intensive educational campaign was conducted. Before the start of the campaign, the NCDC carried out multiple activities including announcing campaign through media, posters, and mobile network as well as educate people that the campaign will maintain high immunity in targeted group and community.
Anecdotal evidence suggest health-care professionals and doctor's advice were the strongest driver in increasing the awareness of the importance of vaccination to build children's immunity. Also indicated they trusted radio and TV ads that featured health-care professionals providing.
A limitation of the current investigation is the change in case-definition pre- and post-vaccination. Changing from a clinical definition to a laboratory definition may lead to a change in sensitivity and specificity which could independently lead to some of the differences identified in measles burden., It is unknown how this may have impacted the proportion of measles cases in the country reported to the NCDC. Previous research in other countries that examine the specificity and sensitivity of clinical diagnosis indicate that clinicians often fail to diagnose cases based on clinical symptoms (sensitivity 33%) indicating burdens prevaccination may have been 3-fold higher. However, it is possible that requiring laboratory confirmation postcampaign may have led to lower proportions of cases being reported if laboratory facilities or blood drawing supplies were unavailable. While this reduces the certainty of the estimate of impact of the vaccination campaign, it is unlikely to completely negate the findings.
In the US, the efficacy of measles vaccine for children aged 12 years and above was >95% during a massive measles outbreak in Ohio in 1976, and Viet Namit was more than 97% during a nationwide measles immunization campaign in 2002. In Poland during an outbreak with 2255 reported measles cases spanning the end of 1997 and the first half of 1998, measles cases reduced by 90% following a single dose of vaccine. In Bangladesh, incidence measles decreased 84% (incidence 40–6/million) during 2000–2016 after three supplementary immunization activities using monovalent measles vaccine with high coverage rate. In rural west Africa, vaccine efficacy was 89% for people aged 9 months and above. All of these previous results are compatible with the high measles vaccine effectiveness determined in Libya. The World Health Assembly endorsed a plan to eliminate measles in 5 of 6 WHO regions by 2020., WHO instituted 3 milestones for measles control: (1) increased routine coverage with the first dose of measles vaccine for children aged 1 year to ≥90% nationwide and ≥80% in each district; (2) reduce global measles incidence to <5 cases per million population; and (3) decrease global measles mortality by 95% comparing with an estimate of year of 2000.,,, Since 2005, Libya implemented their measles elimination program by establishing case-based measles surveillance and confirmation of suspected measles samples by the Measles National Laboratory which was approved by the WHO. As a result of unrest that began in 2011, measles surveillance data are missing from 2011 to 2016. Efforts to re-establish the program are ongoing. Last nationwide measles campaign was in October 2017 which was limited for children aged 3–5 years. It is strongly recommended to implement nationwide measles campaign for more age groups to keep the country in low measles incidence.
| Conclusion|| |
Nationwide measles campaign in 2005 played a significant role in reducing the burden of measles among people in Libya. Measles surveillance program in pre- and postcampaign was the key to demonstrate the effective of the extra vaccine. The efficacy of the campaign was remarkable in decreasing the disease and certainly led to low financial burden. The recommendation of more measles campaign should be taken into consideration which could be justified to insufficient measles surveillance data after the revolution in 2011.
We would express our gratitude to surveillance and response of infectious diseases department in Libya for providing permission to use national measles campaign data. The authors declare that there is no conflict of interests.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2], [Table 3], [Table 4]