Clinical implications of endotoxin concentrations in vaccines

The characteristics and trend of adverse events following immunization reported by information system in Jiangsu province, China, 2015-2018

OBJECTIVE

Adverse events following immunization is an important factor influencing public trust in vaccination. Publicizing its incidence timely can increase public trust. The aim of this study is to describe the incidence and characteristics of adverse events following immunization in Jiangsu province of China from 2015 to 2018.

METHODS

All information of adverse events following immunization (AEFIs) was gained from Jiangsu Province Vaccination Integrated Service Management Information System. The reported AEFI trend was analyzed using Chi-square test.

RESULTS

A total of 77,980 AEFI cases were reported through the AEFI system; Among which, 77,731 were classified as non-serious AEFI cases and 249 were serious AEFI cases. The male to female ratio was 1.31:1, cases less than 7 years old accounted for 97.7%. The total estimated AEFI rate was 62.70/100,000 doses. By severity, 60.75/100,000, 4.46/100,000 and 0.11/100,000 AEFI cases were common vaccine reaction, rare vaccine reaction, and serious rare vaccine reaction, respectively. The top two serious AEFI were thrombocytopenic purpura and febrile. The incidence rates showed the increasing trend and the linear trend of the increasing incidence rates passed the significant test at 0.05 levels.

CONCLUSION

The sensitivity of AEFI monitoring in Jiangsu Province is increasing and higher than the national average and most countries. The majority of AEFI cases were common adverse reactions, while the serious vaccine reactions caused by vaccines were extremely low. To elevate the sensitivity of AEFI surveillance may reduce the incidence of developing serious AEFI cases.

The Adjuvant Bordetella Colonization Factor A Attenuates Alum-Induced Th2 Responses and Enhances Bordetella pertussis Clearance from Mouse Lungs

The reemergence of pertussis or whooping cough in several countries highlights the need for better vaccines. Acellular pertussis vaccines (aPV) contain alum as the adjuvant and elicit Th2-biased immune responses that are less effective in protecting against infection than the reactogenic whole-cell pertussis vaccines (wPV), which elicit primarily a Th1/Th17 response. An important goal for the field is to devise aPV that will induce immune responses similar to those of wPV. We show that Bordetella colonization factor A (BcfA), an outer membrane protein from Bordetella bronchiseptica, has strong adjuvant function and elicits cellular and humoral immune responses to heterologous and Bordetella pertussis antigens. Addition of BcfA to a commercial aPV resulted in greater reduction of B. pertussis numbers from the lungs than that elicited by aPV alone. The more-efficient pathogen clearance was accompanied by increased interleukin-17 (IL-17) and reduced IL-5 and an increased ratio of IgG2/IgG1 antibodies. Thus, our results suggest that BcfA improves aPV-induced responses by modifying the alum-induced Th2-biased aPV response toward Th1/Th17. A redesigned aPV containing BcfA may allow better control of pertussis reemergence by reshaping immune responses to resemble those elicited by wPV immunization.

A proteoliposome formulation derived from Bordetella pertussis induces protection in two murine challenge models

Whooping cough remains a health problem despite high vaccination coverage. It has been recommended that development of new strategies provide long-lasting immunity. The aim of this work was to evaluate the potential of proteoliposomes (PL) extracted from Bordetella pertussis as a vaccine candidate against whooping cough. The size of the B. pertussis PL was estimated to be 96.7 ± 50.9 nm by Scanning Correlation Spectroscopy and the polydispersity index was 0.268. Western blots using monoclonal antibodies revealed the presence of pertussis toxin, pertactin, and fimbriae 3. The Limulus Amebocyte Lisate (LAL) assay showed endotoxin levels lower than those reported for whole cell pertussis licensed vaccines, while the Pyrogen Test indicated 75 ng/mL/Kg. The PL showed high protection capacity in mouse challenge models. There was 89.7% survival in the intracerebral challenge and total reduction of the number of CFU in the intranasal challenge. No significant differences (p > 0.05) were observed between mice immunized with B. pertussis PL and the Cuban DTwP vaccine, whichever challenge model used. These results encouraged us to continue the development of the B. pertussis PL as a component of a new combined vaccine formulated with tetanus and diphtheria toxoids or as a booster dose for adolescents and adults.

Nonclinical vaccine safety evaluation: advantages of continuous temperature monitoring using abdominally implanted data loggers

Fever has been reported as the most common adverse event after vaccination in infants and children. For this reason it is important that, prior to clinical testing of a new vaccine, change in body temperature following vaccination is tested carefully in nonclinical animal studies. Since both the timing and the height of the temperature peak after vaccination may differ from vaccine to vaccine, it is important that the time point for body temperature measurement should be chosen on a case-by-case basis with sufficient knowledge of the specific vaccine. In order to determine the best time point for rectal body temperature measurement after vaccination with a new vaccine candidate against N. meningitidis serogroup B, to be applied in a formal Good Laboratory Practice (GLP) toxicology study, miniature temperature data loggers were implanted into the peritoneal cavity of rabbits. The continuous body temperature monitoring appeared to give a complete picture of the entire body temperature kinetics after vaccination. The body temperature peaked at 4 h after vaccination, and this time point was subsequently applied in the toxicology study. Measured body temperature values at the selected time point of 4 h after vaccination were comparable in the continuous temperature setting and in the formal toxicology study, i.e. rectal temperature measurement at one time point. In the present study implanted temperature loggers were successfully used to define an adequate time point to be applied in determining rectal body temperature in a formal GLP toxicology study with a new vaccine candidate.

Naloxone and alum synergistically augment adjuvant activities of each other in a mouse vaccine model of Salmonella typhimurium infection

Alum is the most commonly used adjuvant for human vaccination but is a poor inducer of cell mediated immunity and T helper 1 (Th1) responses. We have previously shown that naloxone (NLX), which is a general opioid antagonist, acts as an effective adjuvant in enhancing vaccine-induced cellular immunity and Th1 immune responses. Here, we tested the efficacy of an alum-NLX mixture, as a new adjuvant, in the induction of humoral and cellular immunity in response to endotoxin-removed lysate (ERL) of Salmonella typhimurium (S. typhimurium) as a model vaccine. BALB/c mice were divided into five vaccination groups. Mice in the experimental groups received either the ERL vaccine alone or in combination with the adjuvant alum, NLX or the alum-NLX mixture. Mice in the negative control group received phosphate-buffered saline. All mice were immunized on days 0 and 7. Two weeks after the last immunization, immune responses to S. typhimurium were assessed. Our results indicate that including the alum-NLX mixture as an adjuvant during vaccination increased the ability of the ERL vaccine to enhance lymphocyte proliferation, shifted the immune response toward a Th1 profile and increased S. typhimurium-specific IgG, IgG2a and the ratio of IgG2a to IgG1. This resulted in improved protective immunity against S. typhimurium. In conclusion, administering an alum-NLX mixture adjuvant in combination with the ERL vaccine enhances both humoral and cellular immunity, and shifts the immune response to a Th1 pattern.

TLR4 mediates vaccine-induced protective cellular immunity to Bordetella pertussis: role of IL-17-producing T cells

Whole cell pertussis vaccines (Pw) induce Th1 responses and protect against Bordetella pertussis infection, whereas pertussis acellular vaccines (Pa) induce Ab and Th2-biased responses and also protect against severe disease. In this study, we show that Pw failed to generate protective immunity in TLR4-defective C3H/HeJ mice. In contrast, protection induced with Pa was compromised, but not completely abrogated, in C3H/HeJ mice. Immunization with Pw, but not Pa, induced a population of IL-17-producing T cells (Th-17), as well as Th1 cells. Ag-specific IL-17 and IFN-gamma production was significantly lower in Pw-immunized TLR4-defective mice. Furthermore, treatment with neutralizing anti-IL-17 Ab immediately before and after B. pertussis challenge significantly reduced the protective efficacy of Pw. Stimulation of dendritic cells (DC) with Pw promoted IL-23, IL-12, IL-1beta, and TNF-alpha production, which was impaired in DC from TLR4-defective mice. B. pertussis LPS, which is present in high concentrations in Pw, induced IL-23 production by DC, which enhanced IL-17 secretion by T cells, but the induction of Th-17 cells was also dependent on IL-1. In addition, we identified a new effector function for IL-17, activating macrophage killing of B. pertussis, and this bactericidal activity was less efficient in macrophages from TLR4-defective mice. These data provide the first definitive evidence of a role for TLRs in protective immunity induced by a human vaccine. Our findings also demonstrate that activation of innate immune cells through TLR4 helps to direct the induction of Th1 and Th-17 cells, which mediate protective cellular immunity to B. pertussis.

Multivalent recombinant protein vaccine against coccidioidomycosis

Coccidioidomycosis is a human respiratory disease that is endemic to the southwestern United States and is caused by inhalation of the spores of a desert soilborne fungus. Efforts to develop a vaccine against this disease have focused on identification of T-cell-reactive antigens derived from the parasitic cell wall which can stimulate protective immunity against Coccidioides posadasii infection in mice. We previously described a productive immunoproteomic/bioinformatic approach to the discovery of vaccine candidates which makes use of the translated genome of C. posadasii and a computer-based method of scanning deduced sequences of seroreactive proteins for epitopes that are predicted to bind to human major histocompatibility (MHC) class II-restricted molecules. In this study we identified a set of putative cell wall proteins predicted to contain multiple, promiscuous MHC II binding epitopes. Three of these were expressed by Escherichia coli, combined in a vaccine, and tested for protective efficacy in C57BL/6 mice. Approximately 90% of the mice survived beyond 90 days after intranasal challenge, and the majority cleared the pathogen. We suggest that the multicomponent vaccine stimulates a broader range of T-cell clones than the single recombinant protein vaccines and thereby may be capable of inducing protection in an immunologically heterogeneous human population.

Improved protection of mice against lethal respiratory infection with Coccidioides posadasii using two recombinant antigens expressed as a single protein

Two recombinant antigens which individually protect mice from lethal intranasal infection were studied in combination, either as a mixture of two separately expressed proteins or as a single chimeric expression product. Mice vaccinated with either combination survived longer than mice given single antigens. Immunized mice also exhibited specific IgG immunoglobulins and yielded splenocytes which produced interferon-gamma in response to either antigen. The chimeric antigen has the practical advantage of offering enhanced protection from multiple components without increasing production costs.

A review of the Vaccine Adverse Event Reporting System database

The Vaccine Adverse Event Reporting System (VAERS) is an epidemiological database that has been maintained by the FDA and Centers for Disease Control and Prevention (CDC) since 1990. Authors from the National Immunization Programme of the CDC have previously described an epidemiological technique to make qualitative and quantitative measurement in the VAERS database. Application of this technique by ourselves (with further refinements and additions) have resulted in numerous publications showing the VAERS database has good positive predictive value in evaluating vaccine safety concerns that are compatible with observations by many other authors who have analysed different databases. In conclusion, VAERS studies will be particularly critical in the evaluation of the safety of many new or radically changed vaccines expected to be introduced in the relative near future.

An evaluation of serious neurological disorders following immunization: a comparison of whole-cell pertussis and acellular pertussis vaccines

Serious neurological disorders reported following whole-cell pertussis in comparison to acellular pertussis vaccines were evaluated. The Vaccine Adverse Events Reporting System (VAERS) was analyzed for Emergency Department (ED) visits, life-threatening reactions, hospitalizations, disabilities, deaths, seizures, infantile spasms, encephalitis/encephalopathy, autism, Sudden Infant Death Syndrome (SIDS) and speech disorders reported with an initial onset of symptoms within 3 days following whole-cell pertussis and acellular pertussis vaccines among those residing in the US from 1997 to 1999. Controls were employed to evaluate potential biases in VAERS. Evaluations as to whether whole-cell and acellular vaccines were administered to populations of similar age and sex were undertaken because these factors might influence the study's results. Statistical increases were observed for all events examined following whole-cell pertussis vaccination in comparison to acellular pertussis vaccination, excepting cerebellar ataxia. Reporting biases were minimal in VAERS, and whole-cell and acellular pertussis vaccines were administered to populations of similar age and sex. Biologic mechanisms for the increased reactogenicity of whole-cell pertussis vaccines may stem from the fact that whole-cell pertussis vaccines contain 3,000 different proteins, whereas DTaP contains two to five proteins. Whole-cell pertussis vaccine contains known neurotoxins including: endotoxin, pertussis toxin and adenylate cyclase. Our results, and conclusions by the US Institute of Medicine, suggest an association between serious neurological disorders and whole-cell pertussis immunization. In light of the presence of a safer and at least equally efficacious acellular pertussis vaccine alternative, the Japanese and US switch to using acellular pertussis vaccine seems well justified. Other countries using whole-cell pertussis-containing vaccines should consider following suite in the near future.

Incidence of Adverse Reactions to Vaccines in a Paediatric Population

OBJECTIVE

To detect the appearance and specify the types of adverse reactions to vaccines registered in a paediatric population.

PATIENTS AND METHODS

A 6-month, prospective, observational, multicentre epidemiological vaccine safety study was undertaken in 2002 covering a paediatric population subject to vaccine administration. A two-phase telephone survey of all patients was conducted, comprising an initial call at 1 week and a follow-up call at 30 days after the vaccine administration date. A paediatrician was responsible for diagnosing the specific type of adverse reaction.

RESULTS

Of a total sample of 946 children, ranging in age from 0 to 14 years (50.8% girls, 49.1% boys), 191 non-serious suspected adverse reactions were detected, representing 19% of the vaccinated children. Reactions to the diphtheria, tetanus, pertussis acellular and Haemophilus influenzae type b (DTPa + Hib) vaccine appeared in 43.4% of cases, followed by reactions to the measles, mumps, rubella (MMR) [18.4%] and adult tetanus and diphtheria (Td) [17.8%] vaccines. The most frequent types of adverse reactions to vaccines were: injection-site oedema (12.2 per 1000 doses); pain at site of inoculation (10.3 per 1000 doses); temperature not recorded but believed by parents to be very high (4.6 per 1000 doses); and measured temperature indicating fever of 39-40.5 masculineC (4.4 per 1000 doses). Fifty-five percent (n = 21) of cases of injection-site oedema were attributed to DTPa + Hib vaccine (18.8 per 1000 doses), followed by 18.4% (n = 7) attributable to Td vaccine (112 per 1000 doses). Indeed, this latter vaccine was responsible for 43.8% (n = 14; 226 per 1000 doses) of all reported pain at the site of inoculation. MMR vaccine was linked to the occurrence of fever of 39-40.5 masculineC in 52% of cases (n = 10; 29 per 1000 doses). Two children were treated by the emergency services, but there were no deaths or hospitalisations.

CONCLUSIONS

An active search for subjects with suspected adverse reactions to vaccines led to the detection of reactions that are usually not reported. Primary-care physicians and nurses must be vigilant for information on adverse reactions to vaccines in paediatric populations.

Neurodevelopmental disorders after thimerosal-containing vaccines: a brief communication

We were initially highly skeptical that differences in the concentrations of thimerosal in vaccines would have any effect on the incidence rate of neurodevelopmental disorders after childhood immunization. This study presents the first epidemiologic evidence, based upon tens of millions of doses of vaccine administered in the United States, that associates increasing thimerosal from vaccines with neurodevelopmental disorders. Specifically, an analysis of the Vaccine Adverse Events Reporting System (VAERS) database showed statistical increases in the incidence rate of autism (relative risk [RR] = 6.0), mental retardation (RR = 6.1), and speech disorders (RR = 2.2) after thimerosal-containing diphtheria, tetanus, and acellular pertussis (DTaP) vaccines in comparison with thimerosal-free DTaP vaccines. The male/female ratio indicated that autism (17) and speech disorders (2.3) were reported more in males than females after thimerosal-containing DTaP vaccines, whereas mental retardation (1.2) was more evenly reported among male and female vaccine recipients. Controls were employed to determine if biases were present in the data, but none were found. It was determined that overall adverse reactions were reported in similar-aged populations after thimerosal-containing DTaP (2.4 +/- 3.2 years old) and thimerosal-free DTaP (2.1 +/- 2.8 years old) vaccinations. Acute control adverse reactions such as deaths (RR = 1.0), vasculitis (RR = 1.2), seizures (RR = 1.6), ED visits (RR = 1.4), total adverse reactions (RR = 1.4), and gastroenteritis (RR = 1.1) were reported similarly after thimerosal-containing and thimerosal-free DTaP vaccines. An association between neurodevelopmental disorders and thimerosal-containing DTaP vaccines was found, but additional studies should be conducted to confirm and extend this study.

Influenza vaccination and Guillain Barre syndrome

Acute and severe Guillain Barre Syndrome (GBS) cases reported following influenza vaccine to the Vaccine Adverse Events Reporting System (VAERS) database from 1991 through 1999 were examined. Endotoxin concentrations were measured using the Limulus amebocyte lysate assay in influenza vaccines. There were a total of 382 cases of GBS reported to the VAERS database following influenza vaccination (male/female ratio, 1.2). The median onset of GBS following influenza vaccine was 12 days (interquartile range, 7 days to 21 days). There was an increased risk of acute GBS (relative risk, 4.3; 95% confidence interval, 3.0 to 6.4) and severe GBS (relative risk, 8.5; 95% confidence interval, 3.7 to 18.9) in comparison to an adult tetanus-diphtheria (Td) vaccine control group. There were maximums in the incidence of GBS following influenza vaccine that occurred approximately every third year (1993, 1996, and 1998) and statistically significant variation in the incidence of GBS among different influenza manufacturers. Influenza vaccines contained from a 125- to a 1250-fold increase in endotoxin concentrations in comparison to an adult Td vaccine control and endotoxin concentrations varied up to 10-fold among different lots and manufacturers of influenza vaccine. The biologic mechanism for GBS following influenza vaccine may involve the synergistic effects of endotoxin and vaccine-induced autoimmunity. There were minimal potential reporting biases in the data reported to the VAERS database in this study. Patients should make an informed consent decision on whether to take this optional vaccine based upon its safety and efficacy and physicians should vigilantly report GBS following influenza vaccination to the VAERS in the United States so that continued evaluation of the safety of influenza vaccine may be undertaken.