The Lancet 09/2012; 380(9848):1145-6. · 38.28 Impact Factor
ABSTRACT: In 2010, an expert advisory panel convened by the World Health Organization to assess the feasibility of measles eradication concluded that (1) measles can and should be eradicated, (2) eradication by 2020 is feasible if measurable progress is made toward existing 2015 measles mortality reduction targets, (3) measles eradication activities should occur in the context of strengthening routine immunization services, and (4) measles eradication activities should be used to accelerate control and elimination of rubella and congenital rubella syndrome (CRS). The expert advisory panel also emphasized the critical role of research and innovation in any disease control or eradication program. In May 2011, a meeting was held to identify and prioritize research priorities to support measles and rubella/CRS control and potential eradication activities. This summary presents the questions identified by the meeting participants and their relative priority within the following categories: (1) measles epidemiology, (2) vaccine development and alternative vaccine delivery, (3) surveillance and laboratory methods, (4) immunization strategies, (5) mathematical modeling and economic analyses, and (6) rubella/CRS control and elimination.
Vaccine 04/2012; 30(32):4709-16. · 3.77 Impact Factor
ABSTRACT: In most developing countries, rubella vaccine has not been included in the Expanded Programme on Immunization because of lack of information on the burden of disease caused by rubella virus, increased cost associated with adding rubella vaccine, and the concern that if high vaccine coverage cannot be achieved and maintained, the risk of congenital rubella syndrome (CRS) may increase. Data for 2009 reported by countries to the World Health Organization (WHO) and United Nations Children's Fund through the annual Joint Reporting Form were used to indicate patterns in the worldwide use of rubella vaccines, describe the number of reported rubella and CRS cases by WHO Region, and explore factors associated with decisions by countries to introduce rubella vaccine in their national childhood immunization programs. The number of WHO Member States using rubella-containing vaccine (RCV) in their national childhood immunization schedule increased from 83 (43%) in 1996 to 130 (67%) in 2009. Although scheduled ages for rubella vaccination vary across countries and regions, most countries have a 2-dose schedule using a combined measles-mumps-rubella vaccine. Among 130 countries using RCV in 2009, median coverage with the first dose of measles-containing vaccine (MCV1) was 95% (interquartile range [IQR], 90%-98%), compared with a median MCV1 coverage of 76% (IQR, 64%-88%) in countries not using RCV. The median per capita gross national income among 130 countries using RCV was US $6300 (IQR, $3227-$20 916), compared with $635 (IQR, $337-$1027) for 63 countries not using RCV. In 2009, 121 344 rubella cases from 167 countries were reported to WHO. However, only 165 CRS cases were reported globally, of which 67 were in the Eastern Mediterranean Region. Further improvements in surveillance are needed to better document the burden of CRS, and new financing mechanisms will be required to catalyze the introduction of rubella vaccine in developing countries that currently meet the coverage criteria for introduction of rubella vaccine.
The Journal of Infectious Diseases 09/2011; 204 Suppl 2:S579-84. · 6.41 Impact Factor
The Journal of Infectious Diseases 07/2011; 204 Suppl 1:S1-3. · 6.41 Impact Factor
ABSTRACT: Five major disease eradication initiatives were initiated during the second half of the 20th century. The enabling and constraining factors-political, social, economic, and other-for these previous and current eradication programs can inform decision making regarding a proposed measles eradication initiative.
We reviewed the literature on the yaws, malaria, smallpox, guinea worm, and polio eradication programs and compared enabling and constraining factors for each of these programs with the same factors as they relate to a possible measles eradication initiative.
A potential measles eradication program would enjoy distinct advantages in comparison with earlier eradication programs, including strong political and societal support, economic analyses demonstrating a high level of cost-effectiveness, and a rigorous upfront process, compared with previous eradication initiatives, that has validated the feasibility of achieving measles eradication. However, increasing population density, urbanization, and wars/civil conflicts will pose serious challenges.
Measles eradication will be very challenging but probably not as difficult to achieve as polio eradication. Measles eradication should be undertaken only if the commitments and resources will be adequate to meet the political, social, economic, and technical challenges.
The Journal of Infectious Diseases 07/2011; 204 Suppl 1:S54-61. · 6.41 Impact Factor
Vaccine 08/2010; 28(38):6123-4. · 3.77 Impact Factor
ABSTRACT: Global deaths from measles have decreased notably in past decades, due to both increases in immunization rates and decreases in measles case fatality ratios (CFRs). While some aspects of the reduction in measles mortality can be monitored through increases in immunization coverage, estimating the level of measles deaths (in absolute terms) is problematic, particularly since incidence-based methods of estimation rely on accurate measures of measles CFRs. These ratios vary widely by geographic and epidemiologic context and even within the same community from year-to-year.
To understand better the variations in CFRs, we reviewed community-based studies published between 1980 and 2008 reporting age-specific measles CFRs.
The results of the search consistently document that measles CFRs are highest in unvaccinated children under age 5 years; in outbreaks; the lowest CFRs occur in vaccinated children regardless of setting. The broad range of case and death definitions, study populations and geography highlight the complexities in extrapolating results for global public health planning.
Values for measles CFRs remain imprecise, resulting in continued uncertainty about the actual toll measles exacts.
International Journal of Epidemiology 03/2009; 38(1):192-205. · 6.41 Impact Factor
ABSTRACT: To highlight the complications involved in interpreting laboratory tests of measles immunoglobulin M (IgM) for confirmation of infection during a measles outbreak in a highly vaccinated population after conducting a mass immunization campaign as a control measure.
This case study was undertaken in the Republic of the Marshall Islands during a measles outbreak in 2003, when response immunization was conducted. A measles case was defined as fever and rash and one or more of cough, coryza or conjunctivitis. Between 13 July and 7 November 2003, serum samples were obtained from suspected measles cases for serologic testing and nasopharyngeal swabs were taken for viral isolation by reverse transcriptase polymerase chain reaction (RT-PCR).
Specimens were collected from 201 suspected measles cases (19% of total): of the ones that satisfied the clinical case definition, 45% were IgM positive (IgM+) and, of these, 24% had received measles vaccination within the previous 45 days (up to 45 days after vaccination an IgM+ result could be due to either vaccination or wild-type measles infection). The proportion of IgM+ results varied with clinical presentation, the timing of specimen collection and vaccination status. Positive results on RT-PCR occurred in specimens from eight IgM-negative and four IgM+ individuals who had recently been vaccinated.
During measles outbreaks, limiting IgM testing to individuals who meet the clinical case definition and have not been recently vaccinated allows for measles to be confirmed while conserving resources.
Bulletin of the World Health Organisation 03/2009; 87(2):93-8. · 4.64 Impact Factor
ABSTRACT: Numerous evaluations of the clinical sensitivity and specificity of PCR and serologic assays for Bordetella pertussis have been hampered by the low sensitivity of culture, the gold standard test, which leads to biased accuracy estimates. The bias can be reduced by using statistical approaches such as the composite reference standard (CRS) (e.g., positive if culture or serology positive; negative otherwise) or latent class analysis (LCA), an internal reference standard based on a statistical model. We illustrated the benefits of the CRS and LCA approaches by reanalyzing data from a 1995 to 1996 study of cough illness among 212 patients. The accuracy of PCR in this study was evaluated using three reference standards: culture, CRS, and LCA. Using specimens obtained 0 to 34 days after cough onset, estimates of the sensitivity of PCR obtained using CRS (47%) and LCA (34%) were lower than the culture-based estimate (62%). The CRS and LCA approaches, which utilized more than one diagnostic marker of pertussis, likely produced more accurate reference standards than culture alone. In general, the CRS approach is simple, with a well-defined disease status. LCA requires statistical modeling but incorporates more indicators of disease than CRS. When three or more indicators of pertussis are available, these approaches should be used in evaluations of pertussis diagnostic tests.
Clinical and vaccine immunology: CVI 02/2008; 15(1):106-14. · 2.37 Impact Factor
The Journal of Infectious Diseases 12/2007; 196(10):1433-5. · 6.41 Impact Factor
ABSTRACT: In 2002, the UN General Assembly Special Session on Children adopted a goal to reduce deaths owing to measles by half by the end of 2005, compared with 1999 estimates. We describe efforts and progress made towards this goal.
We assessed trends in immunisation against measles on the basis of national implementation of the WHO/UNICEF comprehensive strategy for measles mortality reduction, and the provision of a second opportunity for measles immunisation. We used a natural history model to evaluate trends in mortality due to measles.
Between 1999 and 2005, according to our model mortality owing to measles was reduced by 60%, from an estimated 873,000 deaths (uncertainty bounds 634,000-1,140,000) in 1999 to 345,000 deaths (247,000-458,000) in 2005. The largest percentage reduction in estimated measles mortality during this period was in the western Pacific region (81%), followed by Africa (75%) and the eastern Mediterranean region (62%). Africa achieved the largest total reduction, contributing 72% of the global reduction in measles mortality. Nearly 7.5 million deaths from measles were prevented through immunisation between 1999 and 2005, with supplemental immunisation activities and improved routine immunisation accounting for 2.3 million of these prevented deaths.
The achievement of the 2005 global measles mortality reduction goal is evidence of what can be accomplished for child survival in countries with high childhood mortality when safe, cost-effective, and affordable interventions are backed by country-level political commitment and an effective international partnership.
The Lancet 02/2007; 369(9557):191-200. · 38.28 Impact Factor
ABSTRACT: The last case of poliomyelitis in the United States due to indigenously acquired wild poliovirus occurred in 1979; however, as a consequence of oral poliovirus vaccine (OPV) use that began in 1961, an average of 9 cases of vaccine-associated paralytic poliomyelitis (VAPP) were confirmed each year from 1961 through 1989. To reduce the VAPP burden, national vaccination policy changed in 1997 from reliance on OPV to options for a sequential schedule of inactivated poliovirus vaccine (IPV) followed by OPV. In 2000, an exclusive IPV schedule was adopted.
To review the epidemiology of paralytic poliomyelitis and document the association between the vaccine schedule changes and VAPP in the United States.
Review of national surveillance data from 1990 through 2003 for cases of confirmed paralytic poliomyelitis.
Number of confirmed paralytic poliomyelitis cases, including VAPP, and ratio of VAPP cases to number of doses of OPV distributed that occurred before, during, and after implementation of policy changes.
From 1990 through 1999, 61 cases of paralytic poliomyelitis were reported; 59 (97%) of these were VAPP (1 case per 2.9 million OPV doses distributed), 1 case was imported, and 1 case was indeterminate. Thirteen cases occurred during the 1997-1999 transitional policy period and were associated with the all-OPV schedule; none occurred with the IPV-OPV schedule. No cases occurred after the United States implemented the all-IPV policy in 2000. The last imported poliomyelitis case occurred in 1993 and the last case of VAPP occurred in 1999.
The change in polio vaccination policy from OPV to exclusive use of IPV was successfully implemented; this change led to the elimination of VAPP in the United States.
JAMA The Journal of the American Medical Association 11/2004; 292(14):1696-701. · 30.03 Impact Factor
ABSTRACT: The annual number of reported measles cases in the United States has declined from between 3 million and 4 million in the prevaccine era to <100 cases in association with the highest recorded immunization rates in history. Because of continued importation of measles into the United States, young children who are not vaccinated appropriately may experience more than a 60-fold increase in risk of disease. Unsubstantiated claims suggesting an association between measles vaccine and neurologic disorders have led to reduced vaccine use and a resurgence of measles in countries where immunization rates have declined below the level needed to maintain herd immunity. To address the possibility of worldwide control of measles, efforts to ensure high immunization rates among people in both developed and developing countries must be sustained.
PEDIATRICS 10/2004; 114(4):1065-9. · 4.47 Impact Factor
ABSTRACT: Lessons learned from the successful end of endemic measles virus transmission (i.e., elimination) in the United States include the critical roles of strong political commitment, a regionwide initiative, adequate funding, and a broad coalition of partners. Implications of measles elimination in the United States for global measles control and regional elimination efforts include demonstration of the high vaccination coverage and, in turn, population immunity needed for elimination; the importance of accurate monitoring of vaccination coverage at local, state, and national levels; a vaccination strategy that includes at least 2 opportunities for measles immunization; and the essential role of integrated epidemiological and laboratory surveillance. The United States, with a population of 288 million, is, to our knowledge, the largest country to have ended endemic measles transmission. This experience provides evidence that sustained interruption of transmission can be achieved in large geographic areas, suggesting the feasibility of global eradication of measles.
The Journal of Infectious Diseases 06/2004; 189 Suppl 1:S251-7. · 6.41 Impact Factor
ABSTRACT: To contribute to the development of a rubella vaccination strategy, we conducted a study to determine age-specific susceptibility among women aged 15-39 years by testing for rubella-specific IgG antibodies. Of 964 women, 13% were found to be susceptible to rubella. Significantly higher susceptibility among women >25 years old was observed. Susceptibility data are important but are not sufficient to develop a vaccination strategy. After considering all available information, we suggested vaccination of women aged <35 years and selective vaccination of older women who were planning pregnancy.
Clinical Infectious Diseases 06/2004; 38(12):1780-3. · 9.15 Impact Factor
ABSTRACT: vaccinated persons; later, cases among their family members and other contacts were included. Case reports were transmitted by telephone or telegraph to the Poliomyelitis Surveillance Unit where the data were collated, analyzed, and disseminated via poliomyelitis surveillance reports; the first report was mailed out on May 1, 1955 --- only 3 days after the surveillance activity was initiated. The report was prepared and distributed daily for 5 weeks, weekly for the remainder of the summer and fall, and once every 3--4 weeks during the winter. During the first days of the surveillance program, as more cases were reported, the data demonstrated with increasing certainty that the problem was confined to vaccine produced by a single manufacturer. Production procedures were reviewed and other manufacturers were encouraged to continue vaccine production. W ithout the surveillance program and the rapid clarification of the scope of the problem that was provided by the analysis of national su
The Lancet 365(9454):100-1. · 38.28 Impact Factor
ABSTRACT: Although poliomyelitis due to wild-virus infection has virtually disappeared from Romania, with no cases having been documented between 1984 and 1989, vaccine-associated paralytic poliomyelitis has been reported at very high rates for over two decades. In November 1990, to decrease the risk of vaccine-associated paralytic poliomyelitis, oral poliovirus vaccine produced In Romania was replaced by imported oral vaccine made by a Western European manufacturer. To better quantify the risk of vaccine-associated paralytic poliomyelitis and the impact of the change in vaccine manufacturer, the authors reviewed clinical, epidemiologic, and laboratory data on poliomyelitis cases that occurred in Romania from 1984 to 1992. Poliovirus isolates were characterized at the US Centers for Disease Control and Prevention. During the period 1984–1992, 132 confirmed cases of paralytic poliomyelitis were reported in Romania, of which 13 were classified as wild-virus-associated, 93 as vaccine-asso ciated, and 26 as “of unknown origin.” Wild type 1 poliovirus was isolated during 1990–1992 from nine of 13 (69%) cases in an outbreak that occurred primarily among undervaccinated gypsy children. Vaccine-associated cases were epidemiologically and virologically distinct from wild-virus cases. Of the 93 vaccine-associated cases, 45 children were recipients and 48 were contacts. The overall risk of vaccine-asso ciated paralytic poliomyelitis in Romania (1 case per 183,000 doses of oral poliovirus vaccine distributed) was 14-fold higher than the risk in the United States. The risks of recipient vaccine-associated paralytic poliomyelitis related to the first dose of oral vaccine were similar for Romanian and imported vaccine (1 case per 95,000 doses and 1 case per 65,000 doses, respectively), as were the total risks of vaccine-associated paralytic poliomyelitis. These findings definitively demonstrate a substan tially elevated risk of vaccine-associated paralytic poliomyelitis in Romania which was not affected by a change in oral poliovirus vaccine manufacturer.
The last case of poliomyelitis in the United States due to indigenously
acquired wild poliovirus occurred in 1979; however, as a consequence of oral
poliovirus vaccine (OPV) use that began in 1961, an average of 9 cases of
vaccine-associated paralytic poliomyelitis (VAPP) were confirmed each year
from 1961 through 1989. To reduce the VAPP burden, national vaccination policy
changed in 1997 from reliance on OPV to options for a sequential schedule
of inactivated poliovirus vaccine (IPV) followed by OPV. In 2000, an exclusive
IPV schedule was adopted.Objective
To review the epidemiology of paralytic poliomyelitis and document the
association between the vaccine schedule changes and VAPP in the United States.Design and Setting
Review of national surveillance data from 1990 through 2003 for cases
of confirmed paralytic poliomyelitis.Main Outcome Measures
Number of confirmed paralytic poliomyelitis cases, including VAPP, and
ratio of VAPP cases to number of doses of OPV distributed that occurred before,
during, and after implementation of policy changes.Results
From 1990 through 1999, 61 cases of paralytic poliomyelitis were reported;
59 (97%) of these were VAPP (1 case per 2.9 million OPV doses distributed),
1 case was imported, and 1 case was indeterminate. Thirteen cases occurred
during the 1997-1999 transitional policy period and were associated with the
all-OPV schedule; none occurred with the IPV-OPV schedule. No cases occurred
after the United States implemented the all-IPV policy in 2000. The last imported
poliomyelitis case occurred in 1993 and the last case of VAPP occurred in
The change in polio vaccination policy from OPV to exclusive use of
IPV was successfully implemented; this change led to the elimination of VAPP
in the United States.
Figures in this Article
In 1952, 3 years before the licensure of the first poliomyelitis vaccine,
more than 21 000 cases of paralytic poliomyelitis were documented in
the United States.1 The use of inactivated
poliovirus vaccine (IPV) and, later, oral poliovirus vaccine (OPV) led to
a precipitous drop in reported cases of poliomyelitis.2 The
last cases of poliomyelitis caused by indigenously acquired wild poliovirus
occurred in 1979 during an outbreak following importation from Canada.3 Genetic studies of poliovirus isolates from the 1970s
suggested that endemic circulation of wild polioviruses in the United States
may have ceased by the late 1960s, and subsequent sporadic cases and small
outbreaks due to wild poliovirus during the 1970s probably represented importations
from neighboring countries.4
Monovalent OPV type 3 became available in 1961 in the United States.
Trivalent OPV (offering protection against the 3 poliovirus serotypes) was
licensed in the United States in 1963 and became the vaccine of choice for
prevention of poliomyelitis in the United States and most of the world.5 Oral poliovirus vaccine was considered superior to
IPV because of provision of better intestinal immunity, ability to indirectly
vaccinate susceptible contacts through transmission of vaccine polioviruses,
ease of administration, and lower costs. However, a serious consequence of
the use of this live-virus vaccine, vaccine-associated paralytic poliomyelitis
(VAPP), was recognized as early as 1962.6- 7 From
1961 through 1989, an average of 9 cases of VAPP (range, 1-25 cases) were
confirmed each year.8- 10
In 1988, the World Health Assembly resolved to eradicate poliomyelitis
globally by 2000.11 Universal implementation
of polio eradication strategies substantially reduced the risk of poliovirus
importation into the United States.12 In response
to the changing risk-benefit profile associated with OPV use, the Institute
of Medicine conducted independent evaluations on polio vaccine policy options
in the United States in 1977 and 1988,13- 14 and
in 1995, participated in a policy review initiated by the Centers for Disease
Control and Prevention (CDC) and the Advisory Committee on Immunization Practices.15 The discussion of changing reliance from OPV to IPV
led to national debates in the mid 1990s.16 It
was thought that the potential for reduced compliance due to higher costs
and the increased number of injections associated with IPV, coupled with possible
reduced mucosal immunity in IPV recipients, could lead to wild poliovirus
However, as the likelihood of wild poliovirus importations declined,
the risk of VAPP with routine use of OPV became more difficult to justify.
In June 1996, a policy change was made when the Advisory Committee on Immunization
Practices recommended a transition to IPV by first introducing a sequential
vaccination schedule of 2 doses of IPV followed by 2 doses of OPV.17 This schedule was predicted to reduce the number
of VAPP cases by 53%, with the greatest impact on recipients.19 However,
more flexible policy options were supported by the American Academy of Pediatrics
(AAP) and the American Academy of Family Physicians (AAFP) that allowed for
an all-OPV schedule or an all-IPV schedule, provided parents were educated
about the decision.18,20 In January
1999, the AAP and AAFP revised their recommendations to state that only IPV
should be administered for doses 1 and 2, citing that VAPP continued to be
associated with the all-OPV schedule21 and
that the vaccine options were not always presented to patients and parents.20 Further progress toward global polio eradication
and the desire to eliminate VAPP prompted all policy-setting groups to recommend
that an all-IPV schedule be implemented in 2000.22- 23
This report reviews national poliomyelitis surveillance data in the
United States from 1990 through 2003, describes the epidemiology of poliomyelitis,
and assesses the impact of the poliomyelitis vaccine policy changes on the
occurrence of paralytic poliomyelitis in the United States.
JAMA The Journal of the American Medical Association 292(14):1696-1701. · 30.03 Impact Factor