Patrick Zuber

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 of immunization during pregnancy: A review of the evidence of selected inactivated and live attenuated vaccines

Vaccine-preventable infectious diseases are responsible for significant maternal, neonatal, and young infant morbidity and mortality. While there is emerging scientific evidence, as well as theoretical considerations, indicating that certain vaccines are safe for pregnant women and fetuses, policy formulation is challenging because of perceived potential risks to the fetus. This report presents an overview of available evidence on pregnant women vaccination safety monitoring in pregnant women, from both published literature and ongoing surveillance programs. Safety data were reviewed for vaccines against diseases which increase morbidity in pregnant women, their fetus or infant as well as vaccines which are used in mass vaccination campaigns against diseases. They include inactivated seasonal and pandemic influenza, mono- and combined meningococcal polysaccharide and conjugated vaccines, tetanus toxoid and acellular pertussis combination vaccines, as well as monovalent or combined rubella, oral poliomyelitis virus and yellow fever vaccines. No evidence of adverse pregnancy outcomes has been identified from immunization of pregnant women with these vaccines.

Effectively introducing a new meningococcal A conjugate vaccine in Africa: The Burkina Faso experience

A new Group A meningococcal (Men A) conjugate vaccine, MenAfriVac™, was prequalified by the World Health Organization (WHO) in June 2010. Because Burkina Faso has repeatedly suffered meningitis epidemics due to Group A Neisseria meningitidis special efforts were made to conduct a country-wide campaign with the new vaccine in late 2010 and before the onset of the next epidemic meningococcal disease season beginning in January 2011. In the ensuing five months (July-November 2010) the following challenges were successfully managed: (1) doing a large safety study and registering the new vaccine in Burkina Faso; (2) developing a comprehensive communication plan; (3) strengthening the surveillance system with particular attention to improving the capacity for real-time polymerase chain reaction (PCR) testing of spinal fluid specimens; (4) improving cold chain capacity and waste disposal; (5) developing and funding a sound campaign strategy; and (6) ensuring effective collaboration across all partners. Each of these issues required specific strategies that were managed through a WHO-led consortium that included all major partners (Ministry of Health/Burkina Faso, Serum Institute of India Ltd., UNICEF, Global Alliance for Vaccines and Immunization, Meningitis Vaccine Project, CDC/Atlanta, and the Norwegian Institute of Public Health/Oslo). Biweekly teleconferences that were led by WHO ensured that problems were identified in a timely fashion. The new meningococcal A conjugate vaccine was introduced on December 6, 2010, in a national ceremony led by His Excellency Blaise Compaore, the President of Burkina Faso. The ensuing 10-day national campaign was hugely successful, and over 11.4 million Burkinabes between the ages of 1 and 29 years (100% of target population) were vaccinated. African national immunization programs are capable of achieving very high coverage for a vaccine desired by the public, introduced in a well-organized campaign, and supported at the highest political level. The Burkina Faso success augurs well for further rollout of the Men A conjugate vaccine in meningitis belt countries.

Intussusception and rotavirus vaccination: a review of the available evidence

Two live oral rotavirus vaccines (RotaTeq® and Rotarix®) have recently been recommended by the WHO for inclusion into the national immunization programs of countries worldwide. Owing to the association of the withdrawn Rotashield® vaccine with intussusception, these two new rotavirus vaccines underwent large clinical trials of over 60,000 infants each to assess safety with regard to this medical condition. For these two new vaccines, clinical trials and available postmarketing safety monitoring data do not indicate a risk of intussusception after vaccination, although a low-level risk cannot be excluded at present. We review these safety data for the new vaccines and for Rotashield to provide background information relevant for considering age recommendations for rotavirus vaccination.

International collaboration to assess the risk of Guillain Barre Syndrome following Influenza A (H1N1) 2009 monovalent vaccines

BACKGROUND The global spread of the 2009 novel pandemic influenza A (H1N1) virus led to the accelerated production and distribution of monovalent 2009 Influenza A (H1N1) vaccines (pH1N1). This pandemic provided the opportunity to evaluate the risk of Guillain-Barré syndrome (GBS), which has been an influenza vaccine safety concern since the swine flu pandemic of 1976, using a common protocol among high and middle-income countries. The primary objective of this project was to demonstrate the feasibility and utility of global collaboration in the assessment of vaccine safety, including countries both with and without an established infrastructure for vaccine active safety surveillance. A second objective, included a priori, was to assess the risk of GBS following pH1N1 vaccination. METHODS The primary analysis used the self-controlled case series (SCCS) design to estimate the relative incidence (RI) of GBS in the 42 days following vaccination with pH1N1 vaccine in a pooled analysis across databases and in analysis using a meta-analytic approach. RESULTS We found a relative incidence of GBS of 2.42 (95% CI 1.58-3.72) in the 42 days following exposure to pH1N1 vaccine in analysis of pooled data and 2.09 (95% CI 1.28-3.42) using the meta-analytic approach. CONCLUSIONS This study demonstrates that international collaboration to evaluate serious outcomes using a common protocol is feasible. The significance and consistency of our findings support a conclusion of an association between 2009 H1N1 vaccination and GBS. Given the rarity of the event the relative incidence found does not provide evidence in contradiction to international recommendations for the continued use of influenza vaccines.

Global safety of vaccines: strengthening systems for monitoring, management and the role of GACVS.

Vaccines have contributed enormously in reducing the impact of many infectious diseases, and the expanded use of new and existing vaccines provides unprecedented potential for further reducing the global burden of infectious diseases. Yet, as with the deployment of other technologies, their use may also sometimes be associated with undesirable effects that need to be identified rapidly, understood and minimized. In this article, we review the models and systems that have been developed to monitor and respond to concerns regarding vaccine safety and we give illustrative examples of real or perceived vaccine safety issues. The Global Advisory Committee on Vaccine Safety (GACVS) was set up 10 years ago and charged to provide the WHO with independent advice on vaccine safety issues. The role of the GACVS is both to analyze and to interpret reports of the adverse effects of vaccines that impact on global vaccination programs and strategies, and to foster the development of improved surveillance systems to detect any adverse effects of vaccines, particularly in low- and middle-income countries. It also monitors the development of new vaccines during clinical testing and advises on the safe use of vaccines in immunization programs. As success is achieved with reducing the burden of vaccine-preventable diseases, there will be increasing attention focused on potential adverse effects, on the development of effective surveillance systems to detect adverse effects, and on improved methods to manage and control any harmful consequences of vaccination.

Haemophilus influenzae type b conjugate vaccine is highly effective in the Ugandan routine immunization program: a case–control study

Objective  To study the effectiveness of the Haemophilus influenzae type b (Hib) vaccination program in Uganda.

Assessment of causality of individual adverse events following immunization (AEFI): A WHO tool for global use

Serious illnesses or even deaths may rarely occur after childhood vaccinations. Public health programs are faced with great challenges to establish if the events presenting after the administration of a vaccine are due to other conditions, and hence a coincidental presentation, rather than caused by the administered vaccines. Given its priority, the Global Advisory Committee for Vaccine Safety (GACVS) commissioned a group of experts to review the previously published World Health Organization (WHO) Adverse Event Following Immunization (AEFI) causality assessment methodology and aide-memoire, and to develop a standardized and user friendly tool to assist health care personnel in the processing and interpretation of data on individual events, and to assess the causality after AEFIs. We describe a tool developed for causality assessment of individual AEFIs that includes: (a) an eligibility component for the assessment that reviews the diagnosis associated with the event and identifies the administered vaccines; (b) a checklist that systematically guides users to gather available information to feed a decision algorithm; and (c) a decision support algorithm that assists the assessors to come to a classification of the individual AEFI. Final classification generated by the process includes four categories in which the event is either: (1) consistent; (2) inconsistent; or (3) indeterminate with respect of causal association; or (4) unclassifiable. Subcategories are identified to assist assessors in resulting public health decisions that can be used for action. This proposed tool should support the classification of AEFI cases in a standardized, transparent manner and to collect essential information during AEFI investigation. The algorithm should provide countries and health officials at the global level with an instrument to respond to vaccine safety alerts, and support the education, research and policy decisions on immunization safety.

Poliovirus Vaccine Shedding among Persons with HIV in Abidjan, Cote d’Ivoire

BACKGROUND As polio eradication nears, the development of immunization policies for an era without the disease has become increasingly important. Outbreaks due to circulating vaccine-derived poliovirus (VDPV) and rare cases of immunodeficient persons with prolonged VDPV shedding lend to the growing consensus that oral poliovirus vaccine (OPV) use should be discontinued as soon after polio eradication as possible. The present study was conducted to assess whether persons infected with human immunodeficiency virus (HIV) experience prolonged VDPV shedding and serve as a source of reintroduction of virus into the population. METHODS Adults infected with HIV had specimens tested (1) 8 months after a mass OPV campaign, to determine whether poliovirus related to OPV administered during the campaign was present (i.e., prolonged excretion), and (2) starting 7 weeks after a subsequent campaign, to determine whether poliovirus could be detected after the height of OPV exposure. RESULTS A total of 419 participants were enrolled--315 during the 8-12 months after an OPV campaign held in 2001 and 104 during the 7-13 weeks after a 2002 campaign. No poliovirus was isolated from any participants. CONCLUSIONS It appears unlikely that adults infected with HIV experience prolonged vaccine virus shedding, and, therefore, they probably represent a minimal risk of reintroducing vaccine virus into the population after poliovirus has been eradicated.

Adverse events following immunization during mass vaccination campaigns at first introduction of a meningococcal A conjugate vaccine in Burkina Faso, 2010

MenAfriVac™ is a new meningococcal A conjugate vaccine developed to prevent meningitis outbreaks in Africa. It was first introduced during the last quarter of 2010 in three West African countries. We report on the monitoring of adverse events following immunization (AEFI) in Burkina Faso where more than 11 million people aged 1-29 years were vaccinated. Vaccine pharmacovigilance relied on stimulated passive AEFI surveillance countrywide and active surveillance for 12 clinical conditions in one sentinel district (Ziniaré) with 97,715 people eligible for vaccination. All AEFI occurring during the 10 days of mass campaign or the 42 subsequent days were to be notified. Serious AEFI were submitted to a national expert committee (NEC) for causality assessment. A total of 11,466,950 people were vaccinated with 1471 vaccinees reported to have experienced at least one AEFI (12.83 cases per 100,000). 1444 AEFI were minor; the most common of which were fever, headache, gastro-intestinal disorders and local reactions (2-7 cases per 100,000). Of 27 serious AEFI reported, four cases were classified by the NEC as related to vaccine (1 case per 3 million vaccinated) including one case each of exanthematous pustulosis, angioedema, bronchospasm and severe vomiting. Active surveillance identified 71 cases of the 12 conditions of interest. Convulsions, urticaria and bronchospasm were more frequently reported. Attack rates for those conditions were similar to the baseline rates recorded in the same population, over the same time period, a year earlier. With the exception of convulsions in the days following vaccination the distribution of time intervals between vaccination and the occurrence of symptoms did not reveal any temporal clustering. The monitoring of AEFI of MenAfriVac™ in Burkina Faso did not suggest special concern regarding the vaccine safety. However, reported possible hypersensitivity reactions to vaccine components would require further review to rule out any anaphylactic reaction.