Vitali Pool

Centers for Disease Control and Prevention, Atlanta, Michigan, United States

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Publications (18)60.42 Total impact

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    ABSTRACT: 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.
    Vaccine 03/2008; 26(9):1166-72. DOI:10.1016/j.vaccine.2007.12.049 · 3.49 Impact Factor
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    ABSTRACT: 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. 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. 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. 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). To prevent PPD-vaccine mix-ups, proper storage, handling and administration of vaccine and PPD products is necessary.
    Drug Safety 02/2008; 31(11):1027-33. · 2.62 Impact Factor
  • Drug Safety 01/2008; 31(11):1027-1033. DOI:10.2165/00002018-200831110-00007 · 2.62 Impact Factor
  • Vaccine 09/2007; 25(31):5717-24. DOI:10.1016/j.vaccine.2007.02.067 · 3.49 Impact Factor
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    Vaccine 09/2007; 25(31):5675-84. DOI:10.1016/j.vaccine.2007.02.064 · 3.49 Impact Factor
  • Vitali Pool, John Iskander
    American journal of obstetrics and gynecology 05/2006; 194(4):1200; author reply 1201. DOI:10.1016/j.ajog.2005.07.091 · 3.97 Impact Factor
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    ABSTRACT: The preparation of recombinant hepatitis B vaccines involves using cellular cultures of Saccharomyces cerevisiae, otherwise known as baker's yeast. Prior to vaccine licensure, clinical trials were performed to address whether residual yeast proteins in the vaccines could induce anaphylaxis, including testing for IgE anti-yeast antibody levels. 1-2% of subjects had anti-yeast IgE antibodies before immunization, but demonstrated no significant rise in IgE after HBV. We searched reports in the Vaccine Adverse Event Reporting System (VAERS) for those that mentioned a history of allergy to yeast and then reviewed the adverse events described in these reports for potential anaphylactic reactions. Probable anaphylaxis was defined as the presence of one or more dermatologic symptoms and one or more respiratory, gastrointestinal, or cardiovascular symptoms with onset within 4 h of Hepatitis B vaccination. Possible anaphylaxis was defined in one of two ways: (1) cases that described dermatologic or respiratory symptoms (but not both) occurring within 4h of vaccination; or (2) cases that described one or more dermatologic and/or respiratory symptoms occurring 4-12 h post vaccination. Among the 107 reports of pre-existing "yeast allergies," 11 reports described probable or possible anaphylaxis after HBV. Four additional cases were described after other vaccines. The majority of vaccinees who met the case definitions and had a history of yeast allergies were female, ages ranged from 10 to 64, and symptom onset ranged from 15 min to 5 h after vaccination. No deaths were reported. The small number of reports to VAERS may be partly due to health care professionals observing current contraindications by not vaccinating yeast sensitive individuals. Nevertheless, yeast associated anaphylaxis after HBV in sensitized patients appears to be a rare event.
    Vaccine 03/2006; 24(6):703-7. DOI:10.1016/j.vaccine.2005.07.069 · 3.49 Impact Factor
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    ABSTRACT: 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.
    Drug Safety 02/2006; 29(5):375-84. DOI:10.2165/00002018-200629050-00002 · 2.62 Impact Factor
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    ABSTRACT: Vaccine products currently licensed in the US and other countries are marketed in vials and syringes that may contain natural latex allergens. Little scientific information exists regarding the safety of vaccination of latex-allergic individuals. A review of data within the Vaccine Adverse Event Reporting System (VAERS), a large registry of reported possible vaccine adverse reactions was conducted. A search of the database, which contains >160,000 vaccine adverse event reports, revealed only 28 cases of possible immediate-type hypersensitivity reactions in vaccine recipients with a history of allergy to latex. Given the large number of immunizations administered every year in the US, the reported risk of allergic reactions possibly due to latex contamination of vaccines appears to be very small.
    Vaccine 01/2005; 23(5):664-7. DOI:10.1016/j.vaccine.2004.06.042 · 3.49 Impact Factor
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    ABSTRACT: Post-licensure experience with a new intranasal inactivated influenza vaccine in Switzerland recently identified an increased risk for Bell's palsy. We reviewed reports in the Vaccine Adverse Event Reporting System (VAERS) to assess if parenteral inactivated influenza vaccines (influenza vaccines) may also increase the risk for Bell's palsy. Reports of Bell's palsy after influenza vaccines in VAERS from 1/1/1991 to 12/31/2001 were identified by searching the Coding Symbols for Thesaurus of Adverse Reaction Terms (COSTART) for 'paralysis facial' and by text string search in the automated database. The text descriptions on each report were reviewed to verify the diagnosis. The proportional reporting ratio (PRR) was calculated to aid signal detection. We found a total of 197 reports of Bell's palsy after receipt of influenza vaccines. The diagnosis was verified for 154 (78.2%), of which 145 (94.2%) had received influenza vaccines alone. The verified reports were submitted from 35 states; 58% of the reports involved persons living in states where the risk of Lyme disease, which can also cause facial paralysis, was low, minimal or none. The PRRs in all age groups exceeded the criteria for a signal of possible association. The highest PRR was 3.91 in the > or = 65 years age group. Our findings revealed a signal of possible association between influenza vaccines and an increased risk of Bell's palsy. A population-based controlled study is needed to determine whether this association could be causal and to quantify the risk.
    Pharmacoepidemiology and Drug Safety 08/2004; 13(8):505-10. DOI:10.1002/pds.998 · 3.17 Impact Factor
  • Pharmacoepidemiology and Drug Safety 08/2004; 13(8):515 - 517. DOI:10.1002/pds.1000 · 3.17 Impact Factor
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    ABSTRACT: Background Centers for Disease Control and Prevention (CDC) employees received vaccinia (smallpox) vaccine post 9/11/2001 for bioterrorism preparedness. Unexpectedly, 5 vaccinees were treated for suspected “cellulitis”. An occupational medicine physician (OP) with significant vaccinia practice independently reported a recent increase in vaccinia-associated cellulitis. Extensive clinical, lab, and epidemiological studies supported an alternative diagnosis of RT for these two groups. Since no literature exists on an expected RT rate, we surveyed two other high-volume smallpox vaccination clinics to determine comparative attack rates (AR). Methods Interview of CDC cases established a case definition (CD) of >3 inches redness with swelling, warmth, and pain at vaccination site. Additional CDC cases were found via email survey and diary card review. The OP reported that his cases met the CD. The CD was applied to a chart review at a military facility, and a modified CD (minus warmth) was applied to the database of NIH-University of MD Dryvax dilutional study. Results The varied ARs (2-16%) may be due to the different methods of case ascertainment. All sites reported that irrespective of antibiotic (Abx) therapy, symptoms peaked on post-vaccination day 8-10, and resolved within 24-72 hours. Conclusions Unfamiliarity with RT may have contributed to over-interpretation as “cellulitis”. Future smallpox vaccination programs should provide education on the expected vaccination site evolution and encourage close observation as an alternative to antibiotics.
    Infectious Diseases Society of America 2003 Annual Meeting; 10/2003
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    ABSTRACT: Anaphylaxis after immunization, although rare, is serious and potentially life-threatening. Understanding risk factors for this reaction is therefore important. Gelatin is added to many vaccines as a heat stabilizer. Japanese researchers have demonstrated a strong association between immediate hypersensitivity reactions to measles, mumps, rubella, varicella, and Japanese encephalitis immunizations and subsequent detection of anti-gelatin immunoglobulin E (IgE) antibodies. They suggested that previous receipt by these patients of diphtheria-tetanus-acellular pertussis vaccines with trace amounts of gelatin was responsible for the sensitization. We aimed to assess whether a similar association exists for vaccinees in the United States who reported anaphylaxis after receipt of measles-mumps-rubella (MMR) or measles vaccines and to review recent trends in reporting of hypersensitivity reactions. We conducted a retrospective case-control study. Cases of anaphylaxis that met a predefined case definition were identified from the US Vaccine Adverse Event Reporting System (VAERS). Mayo Clinic patients who received MMR vaccine uneventfully served as controls. The study subjects were interviewed to obtain the history of allergies. Sera from study subjects and their matched controls were tested for IgE antibodies to gelatin, whole egg, and vaccine viral antigens using solid-phase radioimmunoassay. Data from the Biologics Surveillance System on annual numbers of doses of MMR and varicella vaccines distributed in the United States were used to evaluate possible changes in reporting of selected allergic adverse events. Fifty-seven study subjects were recruited into the study and interviewed. Of these, 22 provided serum samples for IgE testing. Twenty-seven subjects served as a comparison group and provided a sample for IgE testing; 21 of these completed an allergy history questionnaire. Self-reported history of food allergies was present more frequently in the interviewed study subjects than in the controls, whereas the proportions of people with other characteristics were similar in both groups. None of the interviewed people had a history of food allergy to gelatin. The level of anti-gelatin IgE antibodies was significantly higher among study subjects than among controls, whereas the levels of IgE antibodies against egg and all 3 viral antigens did not differ significantly. Of 22 study subjects, 6 (27%) tested positive for anti-gelatin IgE, whereas none of the 27 controls did. The rate of anaphylactic reactions reported to VAERS after measles virus-containing immunization in the United States between 1991 and 1997 is 1.8 per 1 million doses distributed. No substantial increase in the number of reported allergic events after frequently used gelatin containing MMR and varicella vaccines could be observed during the first 4 years (1997-2000) since the introduction of diphtheria-tetanus-acellular pertussis vaccines for use in infancy. Anaphylactic reactions to MMR in the United States are rare. The reporting rate has the same order of magnitude as estimates from other countries. Almost one fourth of patients with reported anaphylaxis after MMR seem to have hypersensitivity to gelatin in the vaccine. They may be at higher risk of developing anaphylaxis to subsequent doses of other gelatin-containing vaccines. These people should seek an allergy evaluation before such immunization.
    PEDIATRICS 01/2003; 110(6):e71. DOI:10.1542/peds.110.6.e71 · 5.30 Impact Factor
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    ABSTRACT: Vaccines are usually administered to healthy persons who have substantial expectations for the safety of the vaccines. Adverse events after vaccinations occur but are generally rare. Some adverse events are unlikely to be detected in prelicensure clinical trials because of their low frequency, the limited numbers of enrolled subjects, and other study limitations. Therefore, postmarketing monitoring of adverse events after vaccinations is essential. The cornerstone of monitoring safety is review and analysis of spontaneously reported adverse events. This report summarizes the adverse events reported to the Vaccine Adverse Event Reporting System (VAERS) from January 1, 1991, through December 31, 2001. VAERS was established in 1990 under the joint administration of CDC and the Food and Drug Administration (FDA) to accept reports of suspected adverse events after administration of any vaccine licensed in the United States. VAERS is a passive surveillance system: reports of events are voluntarily submitted by those who experience them, their caregivers, or others. Passive surveillance systems (e.g., VAERS) are subject to multiple limitations, including underreporting, reporting of temporal associations or unconfirmed diagnoses, and lack of denominator data and unbiased comparison groups. Because of these limitations, determining causal associations between vaccines and adverse events from VAERS reports is usually not possible. Vaccine safety concerns identified through adverse event monitoring nearly always require confirmation using an epidemiologic or other (e.g., laboratory) study. Reports may be submitted by anyone suspecting that an adverse event might have been caused by vaccination and are usually submitted by mail or fax. A web-based electronic reporting system has recently become available. Information from the reports is entered into the VAERS database, and new reports are analyzed weekly. VAERS data stripped of personal identifiers can be reviewed by the public by accessing The objectives of VAERS are to 1) detect new, unusual, or rare vaccine adverse events; 2) monitor increases in known adverse events; 3) determine patient risk factors for particular types of adverse events; 4) identify vaccine lots with increased numbers or types of reported adverse events; and 5) assess the safety of newly licensed vaccines. During 1991-2001, VAERS received 128,717 reports, whereas >1.9 billion net doses of human vaccines were distributed. The overall dose-based reporting rate for the 27 frequently reported vaccine types was 11.4 reports per 100,000 net doses distributed. The proportions of reports in the age groups <1 year, 1-6 years, 7-17 years, 18-64 years, and >/= years were 18.1%, 26.7%, 8.0%, 32.6%, and 4.9%, respectively. In all of the adult age groups, a predominance among the number of women reporting was observed, but the difference in sex was minimal among children. Overall, the most commonly reported adverse event was fever, which appeared in 25.8% of all reports, followed by injection-site hypersensitivity (15.8%), rash (unspecified) (11.0%), injection-site edema (10.8%), and vasodilatation (10.8%). A total of 14.2% of all reports described serious adverse events, which by regulatory definition include death, life-threatening illness, hospitalization or prolongation of hospitalization, or permanent disability. Examples of the uses of VAERS data for vaccine safety surveillance are included in this report. As a national public health surveillance system, VAERS is a key component in ensuring the safety of vaccines. VAERS data are used by CDC, FDA, and other organizations to monitor and study vaccine safety. CDC and FDA use VAERS data to respond to public inquiries regarding vaccine safety, and both organizations have published and presented vaccine safety studies based on VAERS data. VAERS data are also used by the Advisory Committee on Immunization Practices and the Vaccine and Related Biological Products Advisory Committee to evaluate possible adverse events after vaccinations and to develop recommendations for precautions and contraindications to vaccinations. Reviews of VAERS reports and the studies based on VAERS reports during 1991-2001 have demonstrated that vaccines are usually safe and that serious adverse events occur but are rare. Through continued reporting of adverse events after vaccination to VAERS by health-care providers, public health professionals, and the public and monitoring of reported events by the VAERS working group, the public health system will continue to be able to detect rare but potentially serious consequences of vaccination. This knowledge facilitates improvement in the safety of vaccines and the vaccination process.
    MMWR. Surveillance summaries: Morbidity and mortality weekly report. Surveillance summaries / CDC 01/2003; 52(1):1-24.
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    ABSTRACT: 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 public's confidence in immunization.
    Clinical Infectious Diseases 01/2002; 33 Suppl 4:S327-33. DOI:10.1086/322569 · 9.42 Impact Factor
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    ABSTRACT: 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.
    Vaccine 08/2000; 18(26):2963-9. · 3.49 Impact Factor
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    ABSTRACT: 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.
    Vaccine 07/2000; DOI:10.1016/S0264-410X(00)00111-0 · 3.49 Impact Factor
  • Vitali Pool, Robert Chen, Philip Rhodes
    The Pediatric Infectious Disease Journal 05/1997; 16(4):423-4. DOI:10.1097/00006454-199704000-00022 · 3.14 Impact Factor