Vitali Pool

Adverse events after Japanese encephalitis vaccination: review of post-marketing surveillance data from Japan and the United States.

We determined the reporting rates for adverse events following the administration of inactivated mouse-brain derived Japanese encephalitis vaccine (JEV) based on post-marketing surveillance data from Japan and the United States. The rate of total adverse events per 100,000 doses was 2.8 in Japan and 15.0 in the United States. In Japan, 17 neurological disorders were reported from April 1996 to October 1998 for a rate of 0.2 per 100,000 doses. In the United States, no serious neurological adverse events temporally associated with JEV were reported from January 1993 to June 1999. Rates for systemic hypersensitivity reactions were 0.8 and 6.3 per 100,000 doses in Japan and the United States, respectively. Passively collected VAERS surveillance data indicate that characteristic hypersensitivity reactions with a delayed onset continue to occur among JEV recipients and that conservative recommendations limiting its use to travelers at high risk of infection with Japanese encephalitis are appropriate.

Data mining in the US using the Vaccine Adverse Event Reporting System.

The US Vaccine Adverse Event Reporting System (VAERS), which is charged with vigilance for detecting vaccine-related safety issues, faces an increasingly complex immunisation environment. Since 1990, steady increases in vaccine licensing and distribution have resulted in increasing numbers of reports to VAERS. Prominent features of current reports include more routine vaccine co-administration and frequent reports of new postvaccination clinical syndromes. Data-mining methods, based on disproportionality analyses, are one strategy being pursued by VAERS researchers to increase the utility of its complex database. The types of analyses used include proportional reporting ratios, association rule discovery, and various ‘historic limits’ methods that compare observed versus expected event counts. The use of such strategies in VAERS has been primarily supplemental and retrospective. Signals for inactivated influenza, typhoid and tetanus toxoid-containing vaccines have been successfully identified. Concerns flagged through data mining should always be subject to clinical case review as a first evaluation step. Persistent issues should be subject to formal hypothesis testing in large linked databases or other controlled-study settings.Automated data-mining techniques for prospective use are currently undergoing development and evaluation within VAERS. Their use (as one signal-detection tool among many) by trained medical evaluators who are aware of system limitations is one legitimate approach to improving the ability of VAERS to generate vaccine-safety hypotheses. Such approaches are needed as more new vaccines continue to be licensed.

Combination Vaccines: Postlicensure Safety Evaluation

The success of immunizations in nearly eliminating many vaccine-preventable diseases has resulted in an increase in the need to study risks from vaccines, combination or otherwise. The well-known limitations associated with prelicensure trials have led many to hope that postlicensure studies can address safety issues. This article reviews measures that have been or should be taken to meet this expectation: establishment of clinical immunization safety assessment centers, standardization of case definitions for vaccine adverse events, use of the Vaccine Identification Standards Initiative to improve the accuracy and efficiency with which vaccination records are transferred, integration of vaccine safety monitoring into immunization registries, establishment (and enlargement) of the Vaccine Safety Datalink project, use of innovative analytic tools for better signal detection, and implementation of various methods to overcome confounding by contraindication. Only by investing in vaccine safety infrastructure at a level commensurate with investments in vaccine development can we hope to retain the publics confidence in immunization.

Live attenuated measles and mumps viral strain-containing vaccines and hearing loss: Vaccine Adverse Event Reporting System (VAERS), United States, 1990–2003

Hearing loss (HL) is a known complication of wild measles and mumps viral infections. As vaccines against measles and mumps contain live attenuated viral strains, it is biologically plausible that in some individuals HL could develop as a complication of vaccination against measles and/or mumps. Our objectives for this study were: to find and describe all cases of HL reported in the scientific literature and to the US Vaccine Adverse Events Reporting System (VAERS) for the period 1990--2003; and to determine reporting rate of HL after live attenuated measles and/or mumps viral strain-containing vaccines (MMCV) administration. We searched published reports for cases of HL identified after vaccination with MMCV. We also searched for reports of HL after MMCV administration submitted to VAERS from 1990 through 2003 and determined the dose-adjusted reporting rate of HL. Our main outcome measure was reported cases of HL after immunization with MMCV which were classified as idiopathic. We found 11 published case reports of HL following MMCV. The review of the VAERS reports identified 44 cases of likely idiopathic sensorineural HL after MMCV administration. The onset of HL in the majority of VAERS and published cases was consistent with the incubation periods of wild measles and mumps viruses. Based on the annual usage of measles-mumps-rubella (MMR) vaccine, we estimated the reporting rate of HL to be 1 case per 6-8 million doses. Thus, HL following MMCV has been reported in the literature and to the VAERS. Further studies are needed to better understand if there is a causal relationship between MMCV and HL.

Preventable mix-ups of tuberculin and vaccines: reports to the US Vaccine and Drug Safety Reporting Systems.

AbstractBackground: Errors involving the mix-up of tuberculin purified protein derivative (PPD) and vaccines leading to adverse reactions and unnecessary medical management have been reported previously. Objectives: To determine the frequency of PPD-vaccine mix-ups reported to the US Vaccine Adverse Event Reporting System (VAERS) and the Adverse Event Reporting System (AERS), characterize adverse events and clusters involving mix-ups and describe reported contributory factors. Methods: We reviewed AERS reports from 1969 to 2005 and VAERS reports from 1990 to 2005. We defined a mix-up error event as an incident in which a single patient or a cluster of patients inadvertently received vaccine instead of a PPD product or received a PPD product instead of vaccine. We defined a cluster as inadvertent administration of PPD or vaccine products to more than one patient in the same facility within 1 month. Results: Of 115 mix-up events identified, 101 involved inadvertent administration of vaccines instead of PPD. Product confusion involved PPD and multiple vaccines. The annual number of reported mix-ups increased from an average of one event per year in the early 1990s to an average of ten events per year in the early part of this decade. More than 240 adults and children were affected and the majority reported local injection site reactions. Four individuals were hospitalized (all recovered) after receiving the wrong products. Several patients were inappropriately started on tuberculosis prophylaxis as a result of a vaccine local reaction being interpreted as a positive tuberculin skin test. Reported potential contributory factors involved both system factors (e.g. similar packaging) and human errors (e.g. failure to read label before product administration). Conclusions: To prevent PPD-vaccine mix-ups, proper storage, handling and administration of vaccine and PPD products is necessary.

Small for gestational age: Case definition & guidelines for data collection, analysis, and presentation of maternal immunisation safety data

2017 Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).