Pertussis vaccine and injury to the brain

Is SARS-CoV-2 vaccination safe and effective for elderly individuals with neurodegenerative diseases?

Introduction

Coronavirus Disease 2019 (COVID-19) poses a substantial threat to the lives of the elderly, especially those with neurodegenerative diseases, and vaccination against viral infections is recognized as an effective measure to reduce mortality. However, elderly patients with neurodegenerative diseases often suffer from abnormal immune function and take multiple medications, which may complicate the role of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines. Currently, there is no expert consensus on whether SARS-CoV-2 vaccines are suitable for patients with neurodegenerative diseases.

Areas covered

We searched Pubmed to conduct a systematic review of published studies, case reports, reviews, meta-analyses, and expert guidelines on the impact of SARS-CoV-2 on neurodegenerative diseases and the latest developments in COVID-19 vaccines. We also summarized the interaction between vaccines and age-related neurodegenerative diseases. The compatibility of future SARS-CoV-2 vaccines with neurodegenerative diseases is discussed.

Expert opinion

Vaccines enable the body to produce immunity by activating the body’s immune response. The pathogenesis and treatment of neurodegenerative diseases is complex, and these diseases often involve abnormal immune function, which can substantially affect the safety and effectiveness of vaccines. In short, this article provides recommendations for the use of vaccine candidates in patients with neurodegenerative diseases.

Selective protection of murine cerebral Gi/o-proteins from inactivation by parenterally injected pertussis toxin

Pertussis toxin (PTX) is a potent virulence factor in patients suffering from whooping cough, but in its detoxified version, it is applied for vaccination. It is thought to contribute to the pathology of the disease including various CNS malfunctions. Based on its enzymatic activity, PTX disrupts GPCR-dependent signaling by modifying the α-subunit of heterotrimeric G_i/o-proteins. It is also extensively used as a research tool to study neuronal functions in vivo and in vitro. However, data demonstrating the penetration of PTX from the blood into the brain are missing. Here, we examined the Gα_i/o-modifying activity of PTX in murine brains after its parenteral application. Ex vivo biodistribution analysis of [¹²⁴I]-PTX displayed poor distribution to the brain while relatively high concentrations were visible in the pancreas. PTX affected CNS and endocrine functions of the pancreas as shown by open-field and glucose tolerance tests, respectively. However, while pancreatic islet Gα_i/o-proteins were modified, their neuronal counterparts in brain tissue were resistant towards PTX as indicated by different autoradiographic and immunoblot SDS-PAGE analyses. In contrast, PTX easily modified brain Gα_i/o-proteins ex vivo. An attempt to increase BBB permeability by application of hypertonic mannitol did not show PTX activity on neuronal G proteins. Consistent with these findings, in vivo MRI analysis did not point to an increased blood-brain barrier (BBB) permeability following PTX treatment. Our data demonstrate that the CNS is protected from PTX. Thus, we hypothesize that the BBB hinders PTX to penetrate into the CNS and to deliver its enzymatic activity to brain Gα_i/o-proteins. KEY MESSAGES: i.p. applied PTX is poorly retained in the brain while reaches high concentration in the pancreas. Pancreatic islet Gα_i/o- but not cerebral Gα_i/o-proteins are modified by i.p. administered PTX. Gα_i/o-proteins from isolated cerebral cell membranes were easily modified by PTX ex vivo. CNS is protected from i.p. administered PTX. PTX does not permeabilize the BBB.

Seizures, encephalopathy, and vaccines: experience in the National Vaccine Injury Compensation Program

OBJECTIVES

To describe the demographic and clinical characteristics of children for whom claims were filed with the National Vaccine Injury Compensation Program (VICP) alleging seizure disorder and/or encephalopathy as a vaccine injury.

STUDY DESIGN

The National VICP within the Department of Health and Human Services compensates individuals who develop medical problems associated with a covered immunization. We retrospectively reviewed medical records of children younger than 2 years of age with seizures and/or encephalopathy allegedly caused by an immunization, where a claim was filed in the VICP between 1995 through 2005.

RESULTS

The VICP retrieved 165 claims that had sufficient clinical information for review. Approximately 80% of these alleged an injury associated with whole-cell diphtheria, pertussis (whooping cough), and tetanus or tetanus, diphtheria toxoids, and acellular pertussis vaccine. Pre-existing seizures were found in 13% and abnormal findings on a neurologic examination before the alleged vaccine injury in 10%. A final diagnostic impression of seizure disorder was established in 69%, of whom 17% (28 patients) had myoclonic epilepsy, including possible severe myoclonic epilepsy of infancy. Specific conditions not caused by immunization, such as tuberous sclerosis and cerebral dysgenesis, were identified in 16% of subjects.

CONCLUSION

A significant number of children with alleged vaccine injury had pre-existing neurologic or neurodevelopmental abnormalities. Among those developing chronic epilepsy, many had clinical features suggesting genetically determined epilepsy. Future studies that include genotyping may allow more specific therapy and prognostication, and enhance public confidence in vaccination.

Vaccination, seizures and ‘vaccine damage’

PURPOSE OF REVIEW

Concerns about the safety of vaccination have plagued the community, with reduction in vaccine uptake resulting in increased risk of epidemics. Vaccination has been implicated in the cause of febrile seizures, 'vaccine encephalopathy' and autistic spectrum disorders. Evaluation of alleged associations is complicated by evolution in the vaccination field. This review focuses on the risk of seizures following vaccination and the alleged associations of vaccination with vaccine encephalopathy and also with autism spectrum disorders.

RECENT FINDINGS

Over the last decade the introduction of new vaccines such as the acellular pertussis vaccine has produced a reduction in seizures following vaccination, the outcome of which was benign even with older vaccines. New evidence emerged in 2006 showing that cases of alleged 'vaccine encephalopathy' are due to mutations within a sodium channel gene. The weight of epidemiological evidence does not support a relationship between vaccination and childhood epileptic encephalopathies or autism spectrum disorders.

SUMMARY

Vaccines are safer than ever before, but the challenge remains to convey this message to society in such a way that produces change in attitudes to vaccination and subsequent increase in vaccine coverage.

De-novo mutations of the sodium channel gene SCN1A in alleged vaccine encephalopathy: a retrospective study

BACKGROUND

Vaccination, particularly for pertussis, has been implicated as a direct cause of an encephalopathy with refractory seizures and intellectual impairment. We postulated that cases of so-called vaccine encephalopathy could have mutations in the neuronal sodium channel alpha1 subunit gene (SCN1A) because of a clinical resemblance to severe myoclonic epilepsy of infancy (SMEI) for which such mutations have been identified.

METHODS

We retrospectively studied 14 patients with alleged vaccine encephalopathy in whom the first seizure occurred within 72 h of vaccination. We reviewed the relation to vaccination from source records and assessed the specific epilepsy phenotype. Mutations in SCN1A were identified by PCR amplification and denaturing high performance liquid chromatography analysis, with subsequent sequencing. Parental DNA was examined to ascertain the origin of the mutation.

FINDINGS

SCN1A mutations were identified in 11 of 14 patients with alleged vaccine encephalopathy; a diagnosis of a specific epilepsy syndrome was made in all 14 cases. Five mutations predicted truncation of the protein and six were missense in conserved regions of the molecule. In all nine cases where parental DNA was available the mutations arose de novo. Clinical-molecular correlation showed mutations in eight of eight cases with phenotypes of SMEI, in three of four cases with borderline SMEI, but not in two cases with Lennox-Gastaut syndrome.

INTERPRETATION

Cases of alleged vaccine encephalopathy could in fact be a genetically determined epileptic encephalopathy that arose de novo. These findings have important clinical implications for diagnosis and management of encephalopathy and, if confirmed in other cohorts, major societal implications for the general acceptance of vaccination.

Lack of evidence of encephalopathy related to pertussis vaccine: active surveillance by IMPACT, Canada, 1993-2002

To assess whether pertussis-containing vaccines cause encephalitis or encephalopathy, the IMPACT network of Canadian pediatric centers screened more than 12,000 admissions for neurologic disorders between 1993 and 2002. Seven cases of encephalopathy began within 7 days after pertussis vaccination, but a more likely cause was found in each instance. No attributable case followed administration of >6.5 million doses of vaccine.

Neurologic complications of immunization

In the United States and many other developed countries, active immunization of children has virtually eliminated poliomyelitis, measles, rubella, tetanus, and other diseases, such as disease due to Haemophilus influenzae type b. Individual vaccines can produce systemic or neurologic reactions ranging from minor events, such as pain and erythema at the injection site, to major complications, such as seizures, shock, encephalopathy, or death. Immunization programs have also generated considerable controversy, as witnessed by recent concerns regarding the relationship between vaccines or their constituents and autism or multiple sclerosis. This review summarizes current information regarding vaccines, the diseases that they prevent, and the potential relationships between vaccines and neurologic disease.

Communicating science to the public: MMR vaccine and autism

Media attention and consequent public concerns about vaccine safety followed publication of a small case-series of children who developed autism after receipt of the measles-mumps-rubella (MMR) vaccine. Many well-controlled studies performed subsequently found no evidence that MMR vaccine causes autism. However, despite these studies, some parents remain concerned that the MMR vaccine is not safe. We will discuss the origins of the hypothesis that the MMR vaccine causes autism, studies performed to test the hypothesis, how these studies have been communicated to the public, and some suggested strategies for how this communication can be improved.

Hypotonic-hyporesponsive episodes reported to the Vaccine Adverse Event Reporting System (VAERS), 1996-1998

BACKGROUND

A hypotonic-hyporesponsive episode (HHE) is the sudden onset of hypotonia, hyporesponsiveness, and pallor or cyanosis that occurs within 48 hours after childhood immunizations. This syndrome has been primarily associated with pertussis-containing vaccines administered to children <2 years of age, and has been estimated to occur once every 1750 diphtheria-tetanus-pertussis (DTwP) vaccinations. Previous studies of HHE were limited by small numbers of cases and, sometimes, by limited details of the event.

OBJECTIVES

To characterize a large number of HHE cases reported to the Vaccine Adverse Event Reporting System (VAERS), to assist clinicians in identifying HHE, and to assist researchers in investigating the risk factors, cause, and pathogenesis of this syndrome.

METHODS

More than 40,000 VAERS reports received between 1996 and 1998 were screened for HHE by a computer algorithm and reviewed, and a telephone follow-up questionnaire was administered to the witness of HHE.

RESULTS

There were 215 HHE cases, all nonfatal. The median age of onset of HHE was 4.0 months (range: 1.1-107 months). Over half of the reports (53%) concerned females. The median birth weight was 3. 36 kg (range: 1.27-4.96 kg); 4.7% had a birth weight <2500 g. The median interval between vaccination and HHE was 210 minutes (range: 1 minute-2 days). Among children with HHE who were <24 months of age, the episode occurred within 5 minutes in only 8.5%, compared with 66.7% of children with HHE >24 months of age. There were no relevant findings regarding family medical history or the mothers' gestational history. Nearly all of the children (98.6%) returned to their prevaccination state according to the telephone questionnaire; median time to return was 6 hours (range: 1 minute- 4 months). The 3 children reported as not returning to their prevaccination state all had VAERS reports submitted after they developed conditions (autism, complex partial epilepsy, and developmental delays with infantile spasms) that are not known to be causally associated with immunization. The vast majority of children (93%) with HHE received a pertussis-containing vaccine, either diphtheria-tetanus-acellular pertussis (DTaP, 28%), DTwP (11%), or diphtheria-tetanus-pertussis-Haemophilus influenzae type b (DTwP-HIB, 61%). During the HHE episode, 90.1% of the children had pallor and 49% had cyanosis. Because of the HHE event, 6.8% of children had had all vaccines withheld as of the date of the interview. Of the remainder, 66.5% of children have had 1 or more subsequent vaccinations or vaccine components withheld, and 26.7% have not had any subsequent vaccinations withheld. Only 1 child was reported to have had a repeat episode of HHE, occurring after hepatitis B vaccination. From 1996 to 1998, the number of HHE reports decreased from 99 to 38, when the predominant pertussis vaccine administered to infants changed from whole-cell to acellular.

CONCLUSION

This study represents the largest published case series of children with HHE and supports the generally benign, self-limited, nonrecurrent nature of this syndrome. Although HHE has been less frequently reported to VAERS after increased use of DTaP, HHE does occur after the administration of DTaP and other nonpertussis-containing vaccines. Although most parents and pediatricians withheld the pertussis component of subsequent vaccinations, many did not, with no reported adverse events occurring in the children after the subsequent immunizations. Restricting the definition of HHE to a more narrow age range (eg, <2 years of age) is also proposed because most of the older children probably experienced vasovagal syncope rather than HHE within 5 minutes of immunization.

Pertussis encephalopathy with high cerebrospinal fluid antibody titers to pertussis toxin and filamentous hemagglutinin

A 7-year-old unimmunized girl with pertussis presented with respiratory failure and electroencephalographic evidence of an encephalopathy. The cerebrospinal fluid (CSF)/serum ratio of antibodies to pertussis toxin and filamentous hemagglutinin were 11- and ninefold higher than the CSF/serum ratio of total immunoglobulin G. The CSF/serum ratio of albumin was normal. These findings indicate production of antibodies in the central nervous system to Bordetella pertussis antigens and imply, therefore, that the pertussis encephalopathy in this girl was associated with the entry of pertussis antigens into the central nervous system.

Immunogenicity and reactogenicity of a booster dose of diphtheria, tetanus, acellular pertussis and inactivated poliomyelitis vaccines given concurrently with Haemophilus type b conjugate vaccine or as pentavalent vaccine

BACKGROUND

The high reactogenicity of whole cell pertussis vaccines discourages their use in children. While acellular pertussis vaccines are less reactogenic, their use in diphtheria-tetanus-acellular pertussis (DTPa)-based combinations with Haemophilus influenzae type b conjugate vaccine (Hib) and poliomyelitis vaccines must be evaluated.

OBJECTIVES

To assess the immunogenicity and reactogenicity of a booster dose of diphtheria, tetanus, acellular pertussis and inactivated poliomyelitis vaccine (DTPa-IPV) given concurrently with Hib as a mixed vaccine or as separate injections, in comparison with a whole cell pertussis vaccine (DTPw-IPV-Hib).

MATERIALS AND METHODS

This open, randomized, controlled study involved 145 healthy children ages 15 to 24 months. Immunogenicity was evaluated for all vaccine antigens, and reactogenicity was assessed with diary cards.

RESULTS

Serum antibody responses to all vaccine antigens was at least as good as that observed with the pentavalent whole cell vaccine. DTPa-IPV was well-tolerated and less reactogenic than the DTPw-IPV vaccine. Administration of DTPa-IPV and Hib vaccine either separately or mixed did not alter the immunogenicity or reactogenicity profiles.

CONCLUSION

DTPa-IPV vaccine, either separately or mixed with Hib vaccine, was at least as immunogenic and less reactogenic than the DTPw-Hib vaccine. Mixing DTPa-IPV and Hib vaccines did not alter the safety profile when compared with separate injections of both vaccines. A mixed DTPa-IPV-Hib vaccine can be recommended for routine use as a booster dose in primed children.

Pertussis: current concepts of pathogenesis and prevention

The selection of acellular vaccine antigens relies on current concepts of pertussis pathogenesis. Animal model data provide evidence that certain products of Bordetella pertussis, which include the putative adhesins filamentous hemagglutinin, pertactin and fimbriae, and pertussis toxin could serve as protective antigens and are available in sufficient quantities of purified material to be considered appropriate candidates for vaccine inclusion. In clinical studies vaccines containing three, four or five components were more effective at preventing pertussis than vaccines containing only inactivated pertussis toxin and filamentous hemagglutinin. These data suggest that pertactin may make a contribution to the protection elicited by an acellular product, but information does not allow evaluation of a possible incremental contribution from fimbriae. Serologic studies of patients in the clinical efficacy trials of the acellular pertussis vaccines did not yield a correlation between antibody levels and protection against pertussis, which suggests that relationships or mechanisms involved in the protective activities of these acellular vaccines are not yet understood. Therefore other mechanisms of immunity (i.e. cellular immunity) may be involved in vaccine-elicited immunity. Increasing understanding of the likely mechanisms of pertussis pathogenesis will provide insights into potential therapies for patients infected with B. pertussis. The mechanisms of vaccine-induced immunity remain elusive and determination of whether these products are working as initially predicted will require further study.

Clinical experience of a tricomponent acellular pertussis vaccine combined with diphtheria and tetanus toxoids for primary vaccination in 22,505 infants

OBJECTIVES

To assess the safety and tolerability of 12 lots of SmithKline Beecham Biologicals' diphtheria-tetanus-tricomponent acellular pertussis vaccine (DTaP) in a large cohort of 22,000 vaccinees, with detailed analyses of reactivity, immunogenicity, and immune response to pertussis toxin in subsets.

METHODS

In a prospective, double-blind, multicenter trial in Germany, 22,505 healthy infants received three vaccinations of DTaP at age 3, 4, and 5 months. Serious adverse events were followed for 1 month after each vaccination, and neurologic events for 1 year or longer. Serum IgG antibodies were assayed before vaccination and 1 month after vaccination.

RESULTS

After 67,000 doses, 153 serious adverse events (0.23%) were reported, 8 considered possibly related, and 5 related to vaccination, including 1 hypotonic-hyporesponsive episode. Incidence rates of sudden infant death syndrome (7; 0.01%) or acute neurologic events (20; 0.030%) were no higher than expected and not considered to be related to vaccination. Redness and swelling of 20 mm or greater occurred after 44 (0.6%) and 40 (0.6%) of the 7270 doses, respectively, and high fever (> 39.5 degrees C) in 6 (0.08%) subjects within 48 hours of vaccination. In the immunogenicity analysis of 580 infants, 98% responded to pertussis toxin, 96% to filamentous hemagglutinin, and 98% to pertactin. In an additional 5712 infants, the response rate to pertussis toxin was 99%.

CONCLUSIONS

In a large cohort of 22,505 infants vaccinated, SmithKline Beecham Biologicals' tricomponent DTaP vaccine was shown to be safe, well-tolerated, and immunogenic for all component antigens.

Surveillance of vaccine-related adverse events in the first year of life: a Manitoba cohort study

This study used data from the population database through which the province of Manitoba, Canada, administers its universal health insurance plan. Enrollment, hospitalization, and immunization files from children born in the 1987-1989 period were linked using the unique identification number assigned to each population member. Analysis of these linked data successfully identified serious potential adverse events in the first year of life and the timing of events around immunization. Not only is population-based active surveillance for immunization-related events feasible, but the techniques described, applied to years of data accumulated through surveillance, offer powerful research tools. Baseline population incidences of adverse events were calculated, temporal relationships between events and immunization assessed, and incidences for events showing true temporal associations determined. Eventual goals are the quantification of vaccine-related risk and the gathering of evidence concerning casual associations. The approach could be used readily by several other Canadian provinces and by health maintenance organizations in the United States.

The family of bacterial ADP-ribosylating exotoxins

Pathogenic bacteria utilize a variety of virulence factors that contribute to the clinical manifestation of their pathogenesis. Bacterial ADP-ribosylating exotoxins (bAREs) represent one family of virulence factors that exert their toxic effects by transferring the ADP-ribose moiety of NAD onto specific eucaryotic target proteins. The observations that some bAREs ADP-ribosylate eucaryotic proteins that regulate signal transduction, like the heterotrimeric GTP-binding proteins and the low-molecular-weight GTP-binding proteins, has extended interest in bAREs beyond the bacteriology laboratory. Molecular studies have shown that bAREs possess little primary amino acid homology and have diverse quaternary structure-function organization. Underlying this apparent diversity, biochemical and crystallographic studies have shown that several bAREs have conserved active-site structures and possess a conserved glutamic acid within their active sites.

The crystal structure of pertussis toxin

BACKGROUND

Pertussis toxin is an exotoxin of the A-B class produced by Bordetella pertussis. The holotoxin comprises 952 residues forming six subunits (five different sequences, S1-S5). It plays an important role in the development of protective immunity to whooping cough, and is an essential component of new acellular vaccines. It is also widely used as a biochemical tool to ADP-ribosylate GTP-binding proteins in the study of signal transduction.

RESULTS

The crystal structure of pertussis toxin has been determined at 2.9 A resolution. The catalytic A-subunit (S1) shares structural homology with other ADP-ribosylating bacterial toxins, although differences in the carboxy-terminal portion explain its unique activation mechanism. Despite its heterogeneous subunit composition, the structure of the cell-binding B-oligomer (S2, S3, two copies of S4, and S5) resembles the symmetrical B-pentamers of the cholera toxin and Shiga toxin families, but it interacts differently with the A-subunit. The structural similarity is all the more surprising given that there is almost no sequence homology between B-subunits of the different toxins. Two peripheral domains that are unique to the pertussis toxin B-oligomer show unexpected structural homology with a calcium-dependent eukaryotic lectin, and reveal possible receptor-binding sites.

CONCLUSION

The structure provides insight into the pathogenic mechanisms of pertussis toxin and the evolution of bacterial toxins. Knowledge of the tertiary structure of the active site forms a rational basis for elimination of catalytic activity in recombinant molecules for vaccine use.

Experience of a specialist service for advice on childhood immunisation

We report a 3 year experience of a specialist clinic set up to advise on childhood immunisation. In all, 20 children were referred for advice on their suitability for measles, mumps, rubella (MMR) immunisation and 93 for advice about pertussis immunisation. All of the former and 78 (84%) of the latter were advised that there were no contraindications to their immunisation. The 20 children given MMR vaccine and 55 (71%) of the 78 who were immunised against pertussis had no adverse effects. The clinic serves a small but important group of children who, because of parental or health care professional uncertainty, may not receive protection against potentially damaging or fatal infections.

Immunization practices in children

The resurgence of measles has highlighted concerns about U.S. programs for immunization in infants and children. In order to put the problems into perspective, this review will address such issues as the safety of pertussis vaccines; oral vs inactivated poliovirus vaccine; vaccines for measles-mumps-rubella, Hemophilus influenzae type B, and hepatitis B; and varicella vaccine.