Challenges of maintaining polio-free status of the European Region.

BACKGROUND: The European region, certified as polio free in 2002, had recent wild poliovirus (WPV) introductions, resulting in a major outbreak in Central Asian countries and Russia in 2010 and in current widespread WPV type 1 circulation in Israel, which endangered the polio-free status of the region. METHODS: We assessed the data on the major determinants of poliovirus transmission risk (population immunity, surveillance, and outbreak preparedness) and reviewed current threats and measures implemented in response to recent WPV introductions. RESULTS: Despite high regional vaccination coverage and functioning surveillance, several countries in the region are at high or intermediate risk of poliovirus transmission. Coverage remains suboptimal in some countries, subnational geographic areas, and population groups, and surveillance (acute flaccid paralysis, enterovirus, and environmental) needs further strengthening. Supplementary immunization activities, which were instrumental in the rapid interruption of WPV1 circulation in 2010, should be implemented in high-risk countries to close population immunity gaps. National polio outbreak preparedness plans need strengthening. Immunization efforts to interrupt WPV transmission in Israel should continue. CONCLUSIONS: The European region has successfully maintained its polio-free status since 2002, but numerous challenges remain. Staying polio free will require continued coordinated efforts, political commitment and financial support from all countries.

Effective vaccine safety systems in all countries: a challenge for more equitable access to immunization.

Serious vaccine-associated adverse events are rare. To further minimize their occurrence and to provide adequate care to those affected, careful monitoring of immunization programs and case management is required. Unfounded vaccine safety concerns have the potential of seriously derailing effective immunization activities. To address these issues, vaccine pharmacovigilance systems have been developed in many industrialized countries. As new vaccine products become available to prevent new diseases in various parts of the world, the demand for effective pharmacovigilance systems in low- and middle-income countries (LMIC) is increasing. To help establish such systems in all countries, WHO developed the Global Vaccine Safety Blueprint in 2011. This strategic plan is based on an in-depth analysis of the vaccine safety landscape that involved many stakeholders. This analysis reviewed existing systems and international vaccine safety activities and assessed the financial resources required to operate them. The Blueprint sets three main strategic goals to optimize the safety of vaccines through effective use of pharmacovigilance principles and methods: to ensure minimal vaccine safety capacity in all countries; to provide enhanced capacity for specific circumstances; and to establish a global support network to assist national authorities with capacity building and crisis management. In early 2012, the Global Vaccine Safety Initiative (GVSI) was launched to bring together and explore synergies among on-going vaccine safety activities. The Global Vaccine Action Plan has identified the Blueprint as its vaccine safety strategy. There is an enormous opportunity to raise awareness for vaccine safety in LMIC and to garner support from a large number of stakeholders for the GVSI between now and 2020. Synergies and resource mobilization opportunities presented by the Decade of Vaccines can enhance monitoring and response to vaccine safety issues, thereby leading to more equitable delivery of vaccines worldwide.

Guillain-barré syndrome following influenza vaccination: causal or coincidental?

In 1976, the emergence of a new swine-origin influenza virus prompted concerns about an impending influenza pandemic. Although the outbreak never materialized, the epidemiological link between Guillain-Barre syndrome, a potentially severe peripheral nerve disorder, and the influenza vaccines developed against this virus caught public health officials, clinicians, and the public by surprise. Subsequently, a great deal of scrutiny has been placed on the possible risk of other formulations of influenza vaccine causing this adverse event. Several epidemiologic and biological assessments have been performed in subsequent years to assess this risk, yet considerable uncertainty remains among health care providers about the possible association. The development and rapid implementation of vaccines against the pandemic 2009 A(H1N1) influenza virus once again highlighted this issue. This article reviews the evidence for and against the association of the 1976 influenza vaccines and subsequent seasonal influenza vaccines with the development of Guillain-Barré syndrome.

Importance of background rates of disease in assessment of vaccine safety during mass immunisation with pandemic H1N1 influenza vaccines.

Because of the advent of a new influenza A H1N1 strain, many countries have begun mass immunisation programmes. Awareness of the background rates of possible adverse events will be a crucial part of assessment of possible vaccine safety concerns and will help to separate legitimate safety concerns from events that are temporally associated with but not caused by vaccination. We identified background rates of selected medical events for several countries. Rates of disease events varied by age, sex, method of ascertainment, and geography. Highly visible health conditions, such as Guillain-Barré syndrome, spontaneous abortion, or even death, will occur in coincident temporal association with novel influenza vaccination. On the basis of the reviewed data, if a cohort of 10 million individuals was vaccinated in the UK, 21.5 cases of Guillain-Barré syndrome and 5.75 cases of sudden death would be expected to occur within 6 weeks of vaccination as coincident background cases. In female vaccinees in the USA, 86.3 cases of optic neuritis per 10 million population would be expected within 6 weeks of vaccination. 397 per 1 million vaccinated pregnant women would be predicted to have a spontaneous abortion within 1 day of vaccination.

Safety profile of pneumococcal conjugate vaccines: systematic review of pre- and post-licensure data.

A 7-valent pneumococcal polysaccharide-protein conjugate vaccine (PCV7) was licensed in the United States of America in 2000, but no comprehensive postmarketing review of safety has been carried out. We conducted a systematic review of the safety of PCV7 and other pneumococcal conjugate vaccines. A total of 42 studies were included in the review. Reactogenicity data from some randomized trials suggest that PCV7 may result in more local reactions and fever than certain comparison vaccines. However, the reactions were mild and self-limited, and PCV7 did not carry an increased risk of severe injection-site reactions or high fever. Some, although not all, of the randomized trials in children found that mild local and systemic reactions associated with PCV7 may increase with the number of doses, at least over the three-dose primary series. In addition, PCV7 and other pneumococcal conjugate vaccines were found to have tolerable reactogenicity in Native American and African populations and in medically high-risk groups for which pneumococcal vaccination is recommended. Two of the largest studies of PCVs, one involving PCV7 and the other, PCV9, found a statistically significant increased risk of hospitalization for reactive airway disease, including asthma. Another large trial of PCV9, however, did not find an increased risk of asthma. In conclusion, this review of the evidence did not identify any major safety problems with PCV7 or any other pneumococcal conjugate vaccine, with the possible exception of reactive airway disease, which may bear further scrutiny as additional data become available.

Influenza vaccination in pregnancy: current evidence and selected national policies.

In several countries, pregnant women are recommended seasonal influenza vaccination and identified as a priority group for vaccination in the event of a pandemic. We review the evidence for the risks of influenza and the risks and benefits of seasonal influenza vaccination in pregnancy. Data on influenza vaccine safety in pregnancy are inadequate, but the few published studies report no serious side-effects in women or their infants, including no indication of harm from vaccination in the first trimester. National policies differ widely, mainly because of the limited data available, particularly on vaccination in the first trimester. The evidence of excess morbidity during seasonal influenza supports vaccinating healthy pregnant women in the second or third trimester and those with comorbidities in any trimester. The evidence of excess mortality in two previous influenza pandemics supports vaccinating in any trimester during a pandemic.

Birth weight of healthy newborns in Zagreb area, Croatia.

The aim of this study was to assess birth weight of healthy newborns from the City of Zagreb and Zagreb County, Croatia. Birth weights of healthy newborns, born at the Department of Obstetrics and Gynecology, University Hospital Center "Zagreb" in the year 2001, were included into analysis. Since there were only few newborns in the 22nd-27th week of gestation, they were excluded from the study. Small number of data points was also noticed in 28th-36th week of gestation, and was supplemented with the data from the years 2000, 2002 and 2003. The method of analysis used in this study was described by Altman and Chitty (Br. J. Obstet. Gynaecol., 101 (1994) 29). After the application of well defined exclusion criteria, the final sample consisted of 4252 newborns. Percentile values for the four groups of newborns (male gender-primipara, male gender-multipara, female gender-primipara, female gender-multipara) were defined, yielding highest birth weight values in the male gender-multipara group (50th percentile of 40th gestational week was 3551.3 g), while female gender-primipara newborns were the lightest among the four sub-samples studied (50th percentile of 40th gestational week was 3399.9 g). New percentile values for percentile curves plotting are presented here and recommended for use in the clinical practice.