The Quest for a Respiratory Syncytial Virus Vaccine for Older Adults: Thinking beyond the F Protein

Respiratory syncytial virus (RSV) is a common cause of paediatric respiratory tract infection and causes a significant health burden in older adults. Natural immunity to RSV is incomplete, permitting recurrent symptomatic infection over an individual's lifespan. When combined with immunosenescence, this increases older adults' susceptibility to more severe disease symptoms. As RSV prophylaxis is currently limited to infants, older adults represent an important target population for RSV vaccine development. The relationship between RSV and our immune systems is complex, and these interactions require deeper understanding to tailor an effective vaccine candidate towards older adults. To date, vaccine candidates targeting RSV antigens, including pre-F, F, G (A), G (B), M2-1, and N, have shown efficacy against RSV infection in older adults in clinical trial settings. Although vaccine candidates have demonstrated robust neutralising IgG and cellular responses, it is important that research continues to investigate the RSV immune response in order to further understand how the choice of antigenic target site may impact vaccine effectiveness. In this article, we discuss the Phase 3 vaccine candidates being tested in older adults and review the hurdles that must be overcome to achieve effective protection against RSV.

Considering the market share of vaccines against tick-borne encephalitis reported in Austria

Different market share values for TBE vaccines in Austria are reported during the period 2018–2020. However, both data likely cover a significant under-estimation of doses distributed. Thus, for epidemiological evaluations, market share should be used with prudence and only reported when solid whole-market market share can be validated and referenced.

The changing epidemiology of human monkeypox-A potential threat? A systematic review

Monkeypox, a zoonotic disease caused by an orthopoxvirus, results in a smallpox-like disease in humans. Since monkeypox in humans was initially diagnosed in 1970 in the Democratic Republic of the Congo (DRC), it has spread to other regions of Africa (primarily West and Central), and cases outside Africa have emerged in recent years. We conducted a systematic review of peer-reviewed and grey literature on how monkeypox epidemiology has evolved, with particular emphasis on the number of confirmed, probable, and/or possible cases, age at presentation, mortality, and geographical spread. The review is registered with PROSPERO (CRD42020208269). We identified 48 peer-reviewed articles and 18 grey literature sources for data extraction. The number of human monkeypox cases has been on the rise since the 1970s, with the most dramatic increases occurring in the DRC. The median age at presentation has increased from 4 (1970s) to 21 years (2010-2019). There was an overall case fatality rate of 8.7%, with a significant difference between clades-Central African 10.6% (95% CI: 8.4%- 13.3%) vs. West African 3.6% (95% CI: 1.7%- 6.8%). Since 2003, import- and travel-related spread outside of Africa has occasionally resulted in outbreaks. Interactions/activities with infected animals or individuals are risk behaviors associated with acquiring monkeypox. Our review shows an escalation of monkeypox cases, especially in the highly endemic DRC, a spread to other countries, and a growing median age from young children to young adults. These findings may be related to the cessation of smallpox vaccination, which provided some cross-protection against monkeypox, leading to increased human-to-human transmission. The appearance of outbreaks beyond Africa highlights the global relevance of the disease. Increased surveillance and detection of monkeypox cases are essential tools for understanding the continuously changing epidemiology of this resurging disease.

A systematic review of invasive pneumococcal disease vaccine failures and breakthrough with higher-valency pneumococcal conjugate vaccines in children

INTRODUCTION

: The pneumococcal non-typeable Haemophilus influenzae protein D-conjugate vaccine (PHiD-CV or PCV10) and 13-valent pneumococcal conjugate vaccine (PCV13) protect against vaccine-serotype invasive pneumococcal disease (VT IPD). However, VT IPD can still occur in fully or partially vaccinated children (vaccine failure or breakthrough). We performed a systematic review of vaccine failures and breakthrough IPD with PCV10 and PCV13 in ≤5-year-olds.

AREAS COVERED

: We searched Scopus/Medline/EMBASE to retrieve articles/abstracts published between 1/2008-7/2019. We excluded reports from studies only including data from adults or children ≥6 years, exclusively assessing PCV7-vaccinated children or children with underlying comorbidities. Twenty-six reports (20 PCV13, 1 PCV10, 5 both), covering studies with various designs in six continents, using different schedules, were included. Collectively, these studies reported 469 VT IPD cases classified as vaccine failures and 403 as breakthrough. Vaccine failure and breakthrough rates were low: 8.4% and 9.3%, respectively, of all IPD in vaccinated children, consistent with the vaccines' high effectiveness. The main serotypes associated with vaccine failure or breakthrough were 19A, 3 and 19F in PCV13 studies and 14, 6B and vaccine-related 19A and 6A in PCV10 studies.

EXPERT OPINION

: As we move to vaccines with more serotypes, it is not only important to consider which serotypes are added, but also to monitor and address incomplete protection against specific serotypes.

One or two doses of hepatitis A vaccine in universal vaccination programs in children in 2020: A systematic review

BACKGROUND

Hepatitis A virus (HAV) is a global health concern as outbreaks continue to occur. Since 1999, several countries have introduced universal vaccination (UV) of children against HAV according to approved two-dose schedules. Other countries have implemented one-dose UV programs since 2005; the long-term impact of this schedule is not yet known.

METHODS

We conducted a systematic literature search in four electronic databases for data published between January 2000 and July 2019 to assess evidence for one-dose and two-dose UV of children with non-live HAV vaccines and describe their global impact on incidence, mortality, and severity of hepatitis A, vaccine effectiveness, vaccine efficacy, and antibody persistence.

RESULTS

Of 3739 records screened, 33 peer-reviewed articles and one conference abstract were included. Rapid declines in incidence of hepatitis A and related outcomes were observed in all age groups post-introduction of UV programs, which persisted for at least 14 years for two-dose and six years for one-dose programs according to respective study durations. Vaccine effectiveness was ≥95% over 3-5 years for two-dose programs. Vaccine efficacy was >98% over 0.1-7.5 years for one-dose vaccination. Antibody persistence in vaccinated individuals was documented for up to 15 years (≥90%) and ten years (≥74%) for two-dose and one-dose schedules, respectively.

CONCLUSION

Experience with two-dose UV of children against HAV is extensive, demonstrating an impact on the incidence of hepatitis A and antibody persistence for at least 15 years in many countries globally. Because evidence is more limited for one-dose UV, we were unable to draw conclusions on immune response persistence beyond ten years or the need for booster doses later in life. Ongoing epidemiological monitoring is essential in countries implementing one-dose UV against HAV. Based on current evidence, two doses of non-live HAV vaccines are needed to ensure long-term protection.

34. Impact of Universal Mass Vaccination Programs of Children Against Hepatitis a with 2-dose and 1-dose Schedules: A Systematic Literature Review

Background

With more than 100 million new hepatitis A (HepA) virus (HAV) infections estimated each year, HepA is a serious health concern worldwide. Several countries implemented 2- or 1-dose universal mass vaccination (UMV) programs of children with HAV vaccines. Here we present the first systematic review describing the impact of 2- and 1-dose UMV programs on HepA incidence and related health outcomes.

Methods

We systematically searched several databases for data published between Jan 2000–Jul 2019 (Figure 1). We assessed available evidence for 2- and 1-dose UMV programs with inactivated HAV vaccine in children worldwide, in terms of impact on HepA incidence, disease severity and mortality, vaccine efficacy, vaccine effectiveness and antibody persistence.

Figure 1. PRISMA flowchart

Results

3739 articles were screened and 34 studies were included in our analysis (Figure 1). 18 real-world studies in 9 countries showed that HepA incidence declined in all ages following introduction of 2-dose and 1-dose UMV programs and persisted for at least 14 years (2-dose) and at least 6 years (1-dose) (Figure 2). Evidence for 1-dose schedule was limited to only 3 studies. HAV related outcomes (disease severity, mortality) decreased after UMV with either 2-dose or 1-dose schedule. Vaccine effectiveness for the 2-dose schedules was ≥ 95% over 3–5 years. Vaccine efficacy for the 1-dose schedule was > 98% over 0.1–7.5 years. Anti-HAV antibody persistence in vaccinated children was documented up to 15 years with ≥ 90% seropositivity rates for the 2-dose schedule and up to 10 years with ≥ 74.3% seropositivity rates for the 1-dose schedule. Anti-HAV antibody GMC data is presented in Table 1.

Figure 2. Impact of vaccination on hepatitis A incidence in countries implementing 2-dose or 1-dose schedules (data from studies presenting ‘all ages’ incidence data)

Table 1. Anti-HAV antibody GMCs following vaccination with 2-dose and 1-dose schedules, data from studies included in our review

Conclusion

The implementation of 2- and 1-dose UMV programs against HAV induced decreases in disease incidence and related outcomes. Experience with 2-dose schedule is extensive, with wide geographical use, while evidence beyond 10 years for the 1-dose schedule has not yet been demonstrated. Continued and robust surveillance is needed to monitor the epidemiology, vaccine effectiveness, antibody persistence and protection (particularly in the absence of natural boosting) in order to have a strong, scientifically sound basis for decision makers when concluding on HepA prevention strategies in their countries.

Funding: GlaxoSmithKline Biologicals SA

Disclosures

Anar Andani, BSc, GSK group of companies (Employee, Shareholder) Eveline M. Bunge, PhD, GSK group of companies (Research Grant or Support) Fernanda Salgado, MD, MSc, GSK group of companies (Employee) Rosa C. van Hoorn, MSc, GSK group of companies (Research Grant or Support) Bernard Hoet, MD, FFPM, GSK group of companies (Shareholder)

Increasing Burden of Hepatitis A in Adolescents and Adults and the Need for Long-Term Protection: A Review from the Indian Subcontinent

Hepatitis A, an acute inflammatory liver disease caused by hepatitis A virus (HAV) infection from close contact with infected people, is highly endemic in the Indian subcontinent. Due to poor sanitary conditions, most of the population is exposed to the virus in childhood. At this age, the disease is asymptomatic and provides life-long protection against the disease. Due to rapid socioeconomic development in some areas, however, pockets of the population are reaching adolescence/adulthood without prior exposure to the virus and are thus susceptible to infection. At these ages, infection carries a higher risk of symptomatic disease and complications including mortality. This review of epidemiology and burden of disease studies in the Indian subcontinent, published since 2005, shows increasing evidence of a shift from high to intermediate endemicity in high-income-typically urban-populations. The prevalence of anti-HAV antibodies (previously reported at > 90%) is lower now in adolescents and young adults (e.g., around 80% in Bangladesh and 55% in 5-15 years in India). As a result, HAV is responsible for more acute viral hepatitis predominantly in this age group (e.g., > 15 years: 3.4% in 1999 to 12.3% in 2003 or high socioeconomic status 13-20 years: 27% in 1999 to 62% in 2003), with a greater clinical and economic burden. Numerous outbreaks due to HAV have been reported [e.g., Sri Lanka (2009-2010): > 13,000 affected; Kashmir (2015-2017): 12 outbreaks; Kerala (2012-2016): 84 outbreaks] from water or food contamination. Due to current shifts in endemicity, a growing proportion of the population is no longer exposed in childhood. As the disease remains highly endemic, it also provides a source for more severe disease in susceptible people at an older age and for outbreaks. Well-tolerated and effective vaccines are available and help prevent disease burden and provide long-term protection. These should now be used more widely to protect more patients from the growing disease burden of hepatitis A. FUNDING: GlaxoSmithKline Biologicals SA. Plain language summary available for this article-please see Fig. 1 and the following link: https://doi.org/10.6084/m9.figshare.9963044.Fig. 1Plain Language Summary. Highlights the context of the article, the endemicity shift and the burden of hepatitis A in adolescents and adults and steps to be taken to address the impact of this disease.

Interchangeability between pneumococcal conjugate vaccines for pediatric use: a systematic literature review

Introduction: Evidence on the interchangeability between the two pediatric pneumococcal conjugate vaccines (PCVs) - pneumococcal non-typeable Haemophilus influenzae protein D-conjugate vaccine (PHiD-CV) and 13-valent PCV (PCV13) - is limited but growing. We performed a systematic literature review to summarize evidence for PHiD-CV/PCV13 interchangeability regarding immunogenicity, safety, and effectiveness against pneumococcal disease. Areas covered: Seven records disclosing results from six studies on PHiD-CV/PCV13 interchangeability were identified. Four clinical trials showed that mixed schedules with a PHiD-CV-to-PCV13 switch at boosting or a PCV13-to-PHiD-CV switch during priming or at boosting were immunogenic with no apparent safety concerns. Two observational studies in the context of a programmatic PHiD-CV-to-PCV13 switch showed similarly high effectiveness against overall invasive pneumococcal disease with a mixed PHiD-CV/PCV13 schedule and a PCV13-only schedule. No effectiveness data for a PCV13-to-PHiD-CV switch and no immunogenicity/safety/effectiveness data for a PHiD-CV-to-PCV13 switch during priming were found. Expert opinion: For epidemiological or programmatic reasons, several local/national authorities have switched PCVs in their immunization programs. Consequently, children have received mixed schedules. Although herd immunity may obscure the individual effect, the limited data are reassuring. Additional evidence from these settings - especially effectiveness or impact data - may provide the necessary information for authorities to make informed decisions on interchanging PCVs.

Would immunization be the same without cross-reactivity?

"Cross-reactivity" (the observed immune response against pathogen types not specifically targeted by the vaccine antigen composition) and "cross-protection" (clinical protection against related non-vaccine microorganism types) are vaccinology concepts that are attracting renewed interest in the context of disease prevention. National health authorities are collecting mounting evidence of the importance of cross-reactivity. For some vaccines, this has been substantiated by cross-protection data from clinical studies and/or post-licensure data, where their introduction into immunization programmes has shown beneficial impacts on disease caused by related non-vaccine microorganisms. This knowledge has influenced the way new vaccines are designed, developed, and evaluated in real-life settings. Some of the new vaccines are now designed with the specific aim of having a greater breadth of protection. Ideal vaccine antigens therefore include epitopes with conserved homology across related pathogen types, because it is not always possible to include the antigens of all the individual types of a given pathogen species. The use of novel adjuvants with greater immunostimulatory properties can also contribute to improved overall vaccine cross-reactivity, as could the use of antigen delivery platforms. The growing body of evidence allows us to better understand the full impact of vaccines - beyond vaccine-type disease - which should be taken into consideration when assessing the full value of vaccination programmes.

Ridogrel, a Combined Thromboxane Synthase Inhibitor and Receptor Blocker, Decreases Elevated Plasma β-Thromboglobulin Levels in Patients with Documented Peripheral Arterial Disease

The combination of thromboxane synthase inhibition with thromboxane receptor antagonism has been shown to result in a strong inhibition of platelet aggregation and a prolongation of the bleeding time (Gresele et al., J. Clin Invest 1987;80: 1435–45).

Ridogrel is a single molecule that efficiently achieves both inhibitions in human volunteers. The present study was performed in patients with obstructive peripheral arterial disease and elevated plasma β-thromboglobulin levels. Patients were treated with either 2 × 300 mg ridogrel or 2 × 300 mg placebo per day for 2½ days, according to a double blind randomised parallel design. Plasma β-thromboglobulin decreased significantly throughout active treatment starting within 2 h after administration; serum and urinary immunoreactive TxB2 levels and urinary 11-dehydro- TxB2 excretion were significantly lower and serum PGE2 and 6-keto-PcF1α levels significantly higher with ridogrel; no changes were observed in the placebo-treated group.

In conclusion this study demonstrates a reduction of platelet activation in vivo by ridogrel.

Synergistic Antiplatelet Effect of Ridogrel, a Combined Thromboxane Receptor Antagonist and Thromboxane Synthase Inhibitor, and UDCG-212, a cAMP-Phosphodiesterase Inhibitor

Ridogrel, a combined thromboxane receptor antagonist and thromboxane synthase inhibitor (1), inhibits platelet aggregation. Following stimulation with arachidonic acid, cAMP-levels are increased in human platelets preincubated with ridogrel, this is due to the known reorientation of the metabolism of the formed endoperoxides towards adenylate cyclase stimulating prostaglandins.

Pretreatment of resting platelets with UDCG-212, a cAMP-phosphodiesterase inhibitor (2), also inhibits platelet aggregation induced by arachidonic acid, concomitant with an increase in cAMP levels, due to an inhibition of its breakdown. Under basal conditions, cAMP also is increased.

By combining the two drugs, a more than additive action was observed on platelet aggregation and on both resting and stimulated platelet cAMP content. The appropriate combination may result in a more effective antiplatelet strategy.

Stability of an aluminum salt-adjuvanted protein D-conjugated pneumococcal vaccine after exposure to subzero temperatures

Accidental exposure of a vaccine containing an aluminum-salt adjuvant to temperatures below 0°C in the cold chain can lead to freeze damage. Our study evaluated the potential for freeze damage in a licensed aluminum-salt-containing protein-D-conjugated pneumococcal vaccine (PHiD-CV; Synflorix, GSK) in conditions that included static storage, single subzero-temperature excursions, and simulated air-freight transportation. Several parameters were assessed including freezing at subzero temperatures, aluminum-salt-particle size, antigen integrity and immunogenicity in the mouse. The suitability of the WHO's shake test for identifying freeze-damaged vaccines was also assessed. During subzero-temperature excursions, the mean temperatures at which PHiD-CV froze (-16.7°C to -18.1°C) appeared unaffected by the type of vaccine container (two-dose or four-dose vial, or single-dose syringe), vaccine batch, rotational agitation, or the rate of temperature decline (-0.5 to -10°C/hour). At constant subzero temperature and in simulated air-freight transportation, the freezing of PHiD-CV appeared to be promoted by vibration. At -5°C, no PHiD-CV sample froze in static storage (>1 month), whereas when subjected to vibration, a minority of samples froze (7/21, 33%) within 18 hours. At -8°C with vibration, nearly all (5/6, 83%) samples froze. In these vibration regimes, the shake test identified most samples that froze (10/12, 93%) except two in the -5°C regime. Nevertheless, PHiD-CV-antigen integrity appeared unaffected by freezing up to -20°C or by vibration. And although aluminum-salt-particle size was increased only by freezing at -20°C, PHiD-CV immunogenicity appeared only marginally affected by freezing at -20°C. Therefore, our study supports the use of the shake test to exclude freeze-damaged PHiD-CV in the field.

Impact of pneumococcal conjugate vaccines on otitis media: A review of measurement and interpretation challenges

Acute otitis media (AOM) is among the most frequent childhood diseases and is caused by various bacterial and viral etiological agents. In this article, we provide an overview of published studies assessing the impact of higher-valent pneumococcal conjugate vaccines (PCVs) on AOM. In some instances, reports of PCV impact on complications of AOM have been included. While randomized controlled trials (RCTs) allow for the most precise assessment of vaccine efficacy against AOM, observational studies provide answers to questions regarding the public health value of these vaccines in real-life settings. We discuss the challenges that arise when measuring PCV impact on AOM in observational studies: the local variability of viral and bacterial etiology, differences in case ascertainment, care-seeking behavior, standards of care and diagnosis of AOM (e.g. use of incisions), as well as declining baseline AOM incidence that can already be in place before PCV introduction, and how these factors can impact the results and their interpretation.

A reflection on invasive pneumococcal disease and pneumococcal conjugate vaccination coverage in children in Southern Europe (2009-2016)

Higher-valent pneumococcal conjugate vaccines (PCVs) were licensed from 2009 in Europe; similar worldwide clinical effectiveness was observed for PCVs in routine use. Despite a proven medical need, PCV vaccination in Southern Europe remained suboptimal until 2015/16.

We searched PubMed for manuscripts published between 2009 and mid-2016. Included manuscripts had to contain data about invasive pneumococcal disease (IPD) incidence, or vaccination coverage with higher-valent PCVs. This review represents the first analysis of vaccination coverage and impact of higher-valent PCVs on overall IPD in Southern European countries (Portugal, Spain, Italy, Greece, Cyprus).

Vaccination coverage in the Portuguese private market peaked around 2008 at 75% (children ≤ 2 years) but declined to 63% in 2012. In Madrid, coverage was 95% (2007–2012) but dropped to 67% (2013/14; children ≤ 2 years) after funding termination in May 2012. PCVs were recently introduced in the national immunisation program (NIP) of Portugal (2015) and Spain (2015/16). In Italy, coverage for the complete PCV schedule (children ≤ 2 years) was 88% in 2013, although highly variable between regions (45–99%). In Greece, in 2013, 82.3% had received 3 PCV doses by 12 months, while 62.3% received the fourth dose by 24 months. Overall IPD (net benefit: effect on vaccine types, vaccine-related types, and non-vaccine types) has decreased; in Greece, pneumococcal meningitis incidence remained stable.

Continued IPD surveillance or national registers using ICD-10 codes of clinically suspected IPD are necessary, with timely publicly available reports and adequate national vaccination registers to assess trends in vaccination coverage, allowing evaluation of PCVs in NIPs.

Response to Wu et al. - Cost-effectiveness analysis of infant pneumococcal vaccination in Malaysia and Hong Kong

A recently published paper that assessed the comparative cost-effectiveness of the 2 pneumococcal conjugate vaccines (PCVs) in Malaysia and Hong Kong reported that the 13-valent PCV vaccine (PCV13) is a better choice compared to the 10-valent pneumococcal non-typeable Haemophilus influenzae protein D conjugate vaccine (PHiD-CV or PCV10) from both a payer and societal perspective as well as under various scenarios. However, the analysis relied on a large number of assumptions that were either erroneous or did not take into account the most recent body of evidence available. A rigorous evaluation of the underlying assumptions is necessary to present a fair and balanced analysis for decision-making.

Further available immunization option to prevent pneumococcal disease

In their recent review, Charles Feldman and Ronald Anderson provide an overview of various clinical aspects of pneumococcal infections. We would like to complete this report by providing some additional information on a widely-used immunization option, which was not originally mentioned in the article. The protein D pneumococcal conjugate vaccine (PHiD-CV) has been pre-approved by WHO and its impact is supported by real-life data from the regions of its use.

Predicting the impact of new pneumococcal conjugate vaccines: serotype composition is not enough

Streptococcus pneumoniae is a major cause of childhood morbidity and mortality worldwide. A heptavalent polysaccharide-protein conjugate vaccine (PCV) has proven highly effective in preventing pneumococcal disease in industrialized countries. Two higher-valent pneumococcal conjugate vaccines are now widely available, even in the poorest countries. These differ from each other in the number of serotypes and carrier proteins used for their conjugation. Some have assumed that the only meaningful clinical difference between PCV formulations is a function of the number of serotypes each contains. A careful review of recent clinical data with these and several unlicensed PCV formulations points to important similarities but also that some key properties of each vaccine likely differ from one another.

Carriage of Streptococcus pneumoniae and other respiratory bacterial pathogens in low and lower-middle income countries: a systematic review and meta-analysis

BACKGROUND

Infection with Streptococcus pneumoniae is a major cause of childhood morbidity and mortality worldwide, especially in low income countries where pneumococcal conjugate vaccines (PCVs) are still underused. In countries where PCVs have been introduced, much of their efficacy has resulted from their impact on nasopharyngeal carriage in vaccinated children. Understanding the epidemiology of carriage for S. pneumoniae and other common respiratory bacteria in developing countries is crucial for implementing appropriate vaccination strategies and evaluating their impact.

METHODS AND FINDINGS

We have systematically reviewed published studies reporting nasopharyngeal or oropharyngeal carriage of S. pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, Staphylococcus aureus, and Neisseria meningitidis in children and adults in low and lower-middle income countries. Studies reporting pneumococcal carriage for healthy children <5 years of age were selected for a meta-analysis. The prevalences of carriage for S. pneumoniae, H. influenzae, and M. catarrhalis were generally higher in low income than in lower-middle income countries and were higher in young children than in adults. The prevalence of S. aureus was high in neonates. Meta-analysis of data from young children before the introduction of PCVs showed a pooled prevalence estimate of 64.8% (95% confidence interval, 49.8%-76.1%) in low income countries and 47.8% (95% confidence interval, 44.7%-50.8%) in lower-middle income countries. The most frequent serotypes were 6A, 6B, 19A, 19F, and 23F.

CONCLUSIONS

In low and lower-middle income countries, pneumococcal carriage is frequent, especially in children, and the spectrum of serotypes is wide. However, because data are limited, additional studies are needed to adequately assess the impact of PCV introduction on carriage of respiratory bacteria in these countries.

Immunogenicity of HBV vaccine during stated shelf-life

Thiomersal has been used as preservative in multi-dose vials of hepatitis B vaccine (Engerix-B). Due to safety concerns, thiomersal was replaced with 2-phenoxyethanol (2PE) as preservative in multi-dose vials. The potency of 2PE preserved hepatitis B vaccine multiple use vials was measured over the shelf-life in terms of immunogenicity, reactogenicity and safety. This single-blind, randomized study was conducted with the assistance of employees of GlaxoSmithKline Biologicals, makers of the Engerix-B vaccine. Four hundred twenty subjects aged > or =18 years were randomized to receive three doses (0, 1, 6 months) of 2PE preserved hepatitis B vaccine kept on the shelf <12 months (2PE New group), 2PE preserved hepatitis B vaccine kept on the shelf >18 months (2PE Old group), or thiomersal preserved hepatitis B vaccine [HBV(Thio) group]. Anti-HBs was measured by GlaxoSmithKline Biologicals post-vaccination; the reactogenicity and safety of the vaccines were assessed. Protective anti-HBs levels (> or =10 mIU/ml) were measured one month after dose 3. The results showed protective levels in 86.8% (2PE New), 89% (2PE Old) and 95.3% [HBV(Thio)]. There was no difference detected between the 2PE New and 2PE Old groups in terms of anti-HBs seroprotection rates and geometric mean concentrations one month after dose 3. However, both 2PE groups had significantly lower seroprotection rates than the HBV(Thio) group and the number of non-responders was higher in the 2PE groups than in the Thio group. A antibody response rates over time were similar between the 2PE New and Old groups. The reactogenicity profiles were acceptable and the ranges were similar for each group. The shelf-life of the vaccines had no impact on immunogenicity or reactogenicity and 2PE preserved hepatitis B vaccine can be considered stable over time.

Do pneumococcal conjugate vaccines provide any cross-protection against serotype 19A?

Background

Introduction of the 7-valent pneumococcal conjugate vaccine (7vCRM) in several countries has led to a rapid, significant drop in vaccine-type invasive pneumococcal disease (IPD) in immunized children. In the United States and some other countries with high antibiotic use, a subsequent rise in serotype 19A IPD has been taken to indicate that the 19F conjugate in the vaccine provides no cross-protection against the immunologically related 19A.

Discussion

We systematically assessed the clinical efficacy and effectiveness of 19F-containing vaccines against 19A disease or nasopharyngeal carriage by searching English-language articles in the electronic databases PubMed, Current contents, Scopus, and Embase from 1985 to 2008. The vaccine efficacy and effectiveness point estimates were consistently positive for modest protection against 19A IPD and acute otitis media (AOM). However, statistical significance was not reached in any individual study. No consistent impact of 7vCRM on 19A nasopharyngeal colonization could be detected. These findings are discussed in context of immunogenicity analyses indicating that 7vCRM induces functionally active anti-19A antibodies after the booster dose, and that other 19F-containing vaccine formulations may elicit higher levels of such antibodies after both primary and booster doses.

Summary

Taken together, these results suggest that 19F-conjugates can provide some protection against 19A disease. The magnitude of this protection in a given setting will likely depend on several factors. These include the anti-19A immunogenicity of the specific vaccine formulation, the number of doses of that formulation needed to elicit the response, and the burden of 19A disease that occurs after those doses. It is possible that a modest protective effect may be obscured by the presence of countervailing selection pressures (such as high antibiotic use) that favor an increase in colonization with antibiotic-non-susceptible strains of 19A.

Long-term immunogenicity of preservative-free hepatitis B vaccine formulations in adults

Vaccination with recombinant hepatitis B vaccines is highly effective in preventing hepatitis B infection. Recently, a preservative-free (PF) formulation of hepatitis B vaccine [GlaxoSmithKline (GSK) Biologicals, Rixensart, Belgium] has been licensed. The immunogenicity of the PF hepatitis B vaccine and antibody persistence 6 years later was assessed in this study. This formulation was compared with the preservative- containing (PC) formulation of the vaccine and a low-preservative (LP) content formulation. Five hundred forty-one healthy adult subjects were evaluated in the primary study. Over 94% of the subjects in the three study groups had seroprotective anti-HBs antibody concentrations (>or=10 mIU/ml) 1 month after completing primary vaccination. Antibody measurements in 242 healthy adults who returned for the follow-up study and who had received primary vaccination 6 years earlier showed that over 81% of subjects in the three study groups still had anti-HBs antibody concentrations >or=10 mIU/ml. No apparent differences in antibody decline or distribution between the study groups were observed. These results indicate that the removal of preservatives from the hepatitis B vaccine does not affect adversely its immunogenicity both in the short and in the longer term.

Long-term benefit of hepatitis B vaccination among children in Thailand with transient hepatitis B virus infection who were born to hepatitis B surface antigen-positive mothers

BACKGROUND

Transmission of hepatitis B virus (HBV) from carrier mothers to their babies appears to be one of the most important factors influencing the prevalence of chronic HBV infection in areas of high hepatitis B endemicity.

METHODS

Infants born to HBV surface antigen (HBsAg)-positive mothers who were or were not positive for HBV e antigen (HBeAg) or to mothers who were negative for both HBsAg and HBeAg have been followed for 17 years for serological evidence of HBV infection. These infants were divided into 2 groups on the basis of their hepatitis B vaccination protocols: group 1 received vaccine at birth and 1, 2, and 12 months later, and group 2 received vaccine at birth and 1 and 6 months later. Follow-up involved annual clinic visits, during which a blood sample was taken and analyzed for the presence of HBsAg, antibody to HBsAg, and antibody to HBV core antigen (HBcAg). Selected blood samples that tested positive for HBV markers during 2 consecutive visits separated by a long interval were further investigated by polymerase chain reaction to detect HBV DNA.

RESULTS

Transient presence of HBsAg or transient and/or long-term presence of antibody to HBcAg suggested that this population was heavily exposed to HBV during the follow-up period. Despite these findings, no new cases of chronic HBV infection were observed. None of the subjects with transient presence of HBsAg had any clinical symptoms of liver disease.

CONCLUSIONS

This study demonstrates the efficacy of the HBV vaccine and its ability to protect against symptomatic disease.

Booster vaccination of adults with reduced-antigen-content diphtheria, Tetanus and pertussis vaccine: immunogenicity 5 years post-vaccination

At 60 months post-vaccination, adults (mean age 45.6 years) randomised to receive combined reduced-antigen-content diphtheria-tetanus and acellular pertussis vaccine (dTpa) versus tetanus-diphtheria (Td)+monovalent acellular pertussis (pa) were seroprotected against diphtheria (> or =0.016IU/mL Vero cell assay) and tetanus (> or =0.1IU/mL ELISA assay) in 94.4% and 96.2%, respectively (dTpa), compared with 93.7% and 90.6% (Td+pa). Anti-FHA, anti-PT and anti-PRN antibodies (> or =5EL.U/mL) were maintained in 100%, 89.5% and 95.0% of dTpa versus 100%, 85.5% and 90.6% of pa vaccine recipients. At 5 years post boosting, antibody levels to diphtheria and tetanus are similar amongst adults receiving a dTpa or dT, and pertussis antibodies remain above pre-booster levels in at least 85%.

A local reaction at or near injection site: case definition and guidelines for collection, analysis, and presentation of immunization safety data

The need for developing a case definition and guidelines for a local reaction at or near the injection site, methods for the development of the case definition and guidelines as an adverse event following immunization as well as the rationale for selected decisions about the case definition for a local reaction at or near the injection site are explained in the Preamble section. The case definition is structured in 2 levels of diagnostic certainty: level 1 includes any description of morphological or physiological change at or near the injection site that is described or identified by a healthcare provider. Level 2 is any description of morphological or physiological change at or near injection site that is described by any other person. In Guidelines section, the working group recommends to enable meaningful and standardized data collection, analysis, and presentation of information about a local reaction at or near the injection site. However, implementation of all guidelines might not be possible in all settings. The availability of information may vary depending upon resources, geographic region, and whether the source of information is a prospectively designed clinical trial, a post-marketing surveillance or epidemiologic study, or an individual report of a local reaction at injection site.

Long-term antibody persistence induced by a combined hepatitis A and B vaccine in children and adolescents

Two cohorts, comprising of subjects aged 1-6 years and 6-15 years were vaccinated with Twinrix according to a 0-, 1- and 6-month schedule. The 1-6 years cohort was followed up for 7.5 years and the 6-15 years cohort for 10 years. At the latest follow-up time point, all subjects were seropositive for anti-HAV antibodies, while 86.5% (32/37) and 95.5% (21/22) had anti-HBs >or= 10 mIU/ml in the 1-6 years and in the 6-15 years cohort. The geometric mean concentrations (GMCs; mIU/ml) were 233 and 680 for anti-HAV antibodies, and 147 and 165 for anti-HBs antibodies, in the 1-6 years and 6-15 years cohorts, respectively. The high persistence of circulating anti-HAV and anti-HBs antibodies in children and adolescents demonstrates the long-term protection offered by Twinrix in these age groups.

Booster vaccination and 1-year follow-up of 4-8-year-old children with a reduced-antigen-content dTpa-IPV vaccine

Reduced-antigen-content pertussis vaccines designed initially for booster vaccination of adolescents and adults can also be used to vaccinate pre-school age children. Combination vaccines, which reduce the number of administered injections, combine multiple antigens including inactivated poliovirus (IPV), which is recommended in this age group in some countries. This randomised, controlled study compared a combined diphtheria-tetanus-acellular pertussis-inactivated polio-containing booster vaccine, dTpa-IPV (Boostrix Polio, n=822), to separately administered dTpa (Boostrix) and IPV (IPV Mérieux, n=136) in 4-8-year-old children who had previously received four doses of DTPa. Additional serological assessment was performed 1 year after the booster dose. One month after vaccination, seroprotection/vaccine response rates were similar for both groups. At least 99.9% of the subjects had protective antibodies against diphtheria, tetanus and polio, and at least 90.1% had a vaccine response to pertussis antigens after dTpa-IPV. Reactogenicity of dTpa-IPV was comparable to dTpa + IPV. Fever and grade 3 loss of appetite occurred more commonly after dTpa-IPV, whereas swelling and grade 3 pain occurred more frequently after separately administered dTpa + IPV (P<0.05 for all). However, 95% CIs overlapped in all cases. Large swelling reactions after dTpa-IPV occurred less commonly than have been reported after a fifth dose of DTPa. One year after the booster, 98.6% of the subjects tested continued to have protective antibodies against diphtheria, tetanus and polio, and at least 81.2% were seropositive for pertussis components. The reduced-antigen-content dTpa-IPV vaccine was immunogenic, well tolerated and safe in pre-school age children. It provides immunity against four diseases in a single injection, with the potential reactogenicity benefit of a reduced-antigen dose.

Primary vaccination of adults with reduced antigen-content diphtheria-tetanus-acellular pertussis or dTpa-inactivated poliovirus vaccines compared to diphtheria-tetanus-toxoid vaccines

OBJECTIVE

To evaluate immunogenicity and reactogenicity of primary vaccination with reduced-antigen-content diphtheria-tetanus-acellular pertussis (dTpa) or dTpa-inactivated poliovirus (dTpa-IPV) vaccine compared to diphtheria-tetanus-toxoid vaccines (Td) in adults > or = 40 years of age without diphtheria or tetanus vaccination for 20 years or with an unknown vaccination history.

RESEARCH DESIGN AND METHODS

Double-blind, randomized, controlled clinical trial. Primary vaccination with either three doses of dTpa, one dose of dTpa-IPV followed by two doses of Td, or three doses of Td vaccine (control) administered in a 0-1-6-month schedule.

MAIN OUTCOME MEASURES

Blood samples were collected before commencement and 1 month after each dose. Local and general symptoms were solicited for 15 days after each dose.

RESULTS

A total of 460 adults were enrolled, of whom over 48% did not have protective antibody concentrations against diphtheria and tetanus. One month after dose 3 > 99% had seroprotective anti-diphtheria and tetanus antibodies. Three doses were required to maximize anti-diphtheria seroprotection rates. A vaccine response to pertussis antigens was observed in > 92% of dTpa and dTpa-IPV recipients after dose 1. One month after dTpa-IPV, > 98.4% had seroprotective anti-polio titres. No statistically significant differences in local or general symptoms between groups were observed.

CONCLUSIONS

dTpa and dTpa-IPV can provide primary vaccination of adults. Combinations of dTpa or dTpa-IPV can be used to replace Td and provide booster vaccination against pertussis and polio simultaneously with diphtheria and tetanus, even in situations where the primary vaccination history is unknown.

Nigerian medical students are at risk for hepatitis B infection

Medical students are exposed to blood and body fluids. This study was conducted to estimate the prevalence of hepatitis B virus (HBV) infection amongst medical students of the Lagos State University College of Medicine, Ikeja, Nigeria. Data were collected through a self-administered questionnaire and through blood analysis for hepatitis B surface antigen (HBsAg), hepatitis B 'e' antigen (HBeAg) as well as antibodies to the core (anti-HBc), surface (anti-HBs) and 'e' (anti-HBe) antigens. Three hundred and thirteen of 325 students (96%) participated. The mean age was 24.3+/-3.98 years; 231 (74%) were pre-clinical students and 82 (26%) were in the clinical years of study. Only 8 (2.6%) had received three doses of vaccination against HBV. Eighty-one (26%) tested positive for anti-HBc, 10 (3.2%) were positive for HBsAg and 56 (17.9%) had anti-HBs antibodies. A significant relationship was found between students who had a positive history of hepatitis B in the family and anti-HBc (P=0.03). Age was also significantly associated with HBsAg (P=0.012). Two hundred and twenty-five (72%) students were susceptible to the infection and required vaccination. Most students at this medical school are susceptible to HBV infection and should be vaccinated.

Immunogenicity, reactogenicity and safety of two-dose versus three-dose (standard care) hepatitis B immunisation of healthy adolescents aged 11–15 years: A randomised controlled trial

This trial assessed the immunogenicity, safety and reactogenicity of a two-dose hepatitis B immunisation regimen (thiomersal-free Engerix-B 20 microg HBsAg doses 6 months apart) compared to the standard three-dose vaccination regimen (preservative-free Engerix-B 10 microg HBsAg doses, 0, 1, 6 month dose schedule) in healthy adolescents aged 11-15 years. Subjects were randomly assigned (2:1 ratio) to one of the two regimens (258 to the two-dose [20 microg] and 126 to the three-dose [10 microg] regimen) (Study ID 103860/280). One month after the final vaccine dose, the seroprotection (anti-HBs >or=10mIU/ml) rate in the two-dose (20 microg) group (233/241 individuals -96.7% seroprotected) was non-inferior to the seroprotection rate in the three-dose (10 microg) group (111/113 individuals -98.2% seroprotected). Both regimens were shown to be safe and well tolerated. Two doses of Engerix-B (20 microg HBsAg) could be considered as an alternative to standard three-dose Engerix-B (10 microg HBsAg) immunisation for adolescents aged 11-15 years.

Antibody persistence and immune memory elicited by combined hepatitis A and B vaccination in older adults

Response to hepatitis A and B vaccines has been reported to decline with age. This open, prospective, single-site study examined the long-term response to the combined hepatitis A/B vaccine Twinrix in 98 primary responders aged 45-67 years. Levels of antibody against hepatitis A virus (HAV) and hepatitis B surface antigen (HBs) were tested 30 months after initial vaccination. At this stage, all participants remained seropositive for anti-HAV and 70% for anti-HBs. A booster vaccination was offered to those who had responded to the first vaccination but then lost protective levels of anti-HBs. An anamnestic response was observed in all cases.

Ten-year antibody persistence induced by hepatitis A and B vaccine (Twinrix) in adults

BACKGROUND

Hepatitis A and B infections are prevalent worldwide and cause significant morbidity and mortality. A combined vaccine providing dual protection against hepatitis A and B is available (Twinrix, GlaxoSmithKline Biologicals).

METHOD

Two cohorts of adults aged 17-43 years were vaccinated with Twinrix according to a 0, 1, 6 months schedule and followed up for 10 years.

RESULTS

One month after the primary vaccination course (Month 7), all subjects were seropositive for anti-HAV and all had anti-HBs> or = 10 mIU/ml. At month 120, 100% of subjects (N=34; N=29) in both cohorts were seropositive for anti-HAV; 94.1% and 86.2% of subjects had anti-HBs > or = 10 mIU/ml. The geometric mean concentrations (GMC; mIU/ml) were 373.9 and 674.6 in the two cohorts for anti-HAV, and 103.8 and 320.0, respectively, for anti-HBs. None of the serious adverse events reported throughout the follow-up period were considered by the investigator to be causally related to vaccination.

CONCLUSIONS

Combined hepatitis A and B vaccine, Twinrix, is safe, well-tolerated and has demonstrated a highly immunogenic profile. Persistence of anti-HAV and anti-HBs antibodies in adults remains high for at least 10 years after primary vaccination.

Development and clinical testing of multivalent vaccines based on a diphtheria-tetanus-acellular pertussis vaccine: difficulties encountered and lessons learned

The widespread use of whole-cell pertussis vaccines in the second half of the 20th century have reduced the incidence of the disease significantly. However, in some countries, concerns about the reactogenicity and potential neurological damage associated with whole-cell vaccines led to a decrease in vaccine acceptance and an increase in morbidity and mortality of pertussis in several countries. This prompted the development of less reactogenic acellular pertussis vaccines combined with diphtheria and tetanus toxoids, initially in Japan and later in other countries. In Europe, the improved diphtheria, tetanus and acellular pertussis (DTPa) vaccine was first introduced in March 1994. The pertussis component of this DTPa vaccine, developed by Glaxo SmithKline, consists of pertussis toxoid, filamentous haemagglutinin and pertactin. The vaccine is well tolerated, with a lower incidence of adverse reactions than after administration of whole-cell vaccines. The long-lasting efficacy and effectiveness of DTPa vaccines have been extensively documented and these are now the cornerstone of a large range of combined vaccines including DTPa-hepatitis B (HBV), DTPa-inactivated polio (IPV) and DTPa-HBV-IPV. A lyophilised Haemophilus influenzae type b (Hib) vaccine can be reconstituted with all of these liquid combinations. The introduction of well-tolerated and efficacious DTPa vaccines and their more polyvalent combinations has improved the acceptance and simplified the implementation of childhood immunisation. This paper is a review of the technical and scientific difficulties encountered and the lessons learned over the 10-year period that it took to develop and introduce six multivalent vaccines using the Glaxo SmithKline DTPa as a building block.

Epidemiological typing of Bordetella pertussis isolates: recommendations for a standard methodology

Pertussis is re-emerging in vaccinated populations, and to gain insight into the reasons for this development population-based studies are necessary. Unfortunately, various techniques are used to study Bordetella pertussis populations, hampering comparison between studies. A standard methodology for epidemiological typing of Bordetella pertussis isolates is proposed which is based on serotyping, pulsed-field gel electrophoresis and gene typing. Such a standard approach will allow comparisons between studies performed in different laboratories. Comparisons may reveal whether the epidemiological differences observed between countries are due for instance to different Bordetella pertussis populations or different vaccines used.

Prevalence of herds with young sows seropositive to pseudorabies (Aujeszky's disease) in northern Belgium

In Belgium, pseudorabies in swine has been the subject of a mandatory eradication programme since 1993. From December 1995 to February 1996, a survey was conducted in the five provinces of northern Belgium to estimate the provincial pseudorabies virus (PRV) herd seroprevalence. Seven hundred and twenty randomly selected herds were included in this survey. To detect recently infected animals, only young sows were sampled. The results show that 44% of these herds had an important number of PRV-seropositive young sows. The highest herd seroprevalence was observed in West Flanders (68%), followed by Antwerp (60%), East Flanders (43%), Limburg (18%), and Flemish Brabant (8%). Assuming a diagnostic test sensitivity and specificity of 95% and 99%, respectively, and a true PRV within-herd prevalence of 43%, the overall true PRV herd prevalence was estimated to be 35%. A logistic multiple-regression revealed that the presence of finishing pigs was associated with a two-fold increase in odds of a herd being seropositive (odds ratio (OR)=2.07, 95% confidence interval (CI) = 1.31-3.26); a breeding herd size > or =70 sows was associated with a four-fold increase in odds of a herd being seropositive (OR = 4.09, 95% CI = 2.18-7.67); a pig density in the municipality of >455 pigs/km2 was associated with a 10-fold increase in odds of a herd being seropositive (OR = 9.68, 95% CI = 5.17-18.12). No association was detected between the PRV herd seroprevalence and purchase policy of breeding pigs (purchased gilts, or use of homebred gilts only).

An echistatin-like Arg-Gly-Asp (RGD)-containing sequence in the heavy chain CDR3 of a murine monoclonal antibody that inhibits human platelet glycoprotein IIb/IIIa function

We describe the production and biochemical characterization of the first GPIIb/IIIa-inhibiting monoclonal antibody that contains an RGD sequence in the CDR3 region of the heavy chain. Monoclonal antibodies obtained by immunizing mice with human platelets were screened using consecutive ELISAs based on human platelets and immuno-affinity-purified glycoprotein (GP) IIb/IIIa coated on microtitre plates. Out of 30 monoclonal antibodies reacting with GPIIb/IIIa, one, MA-16N7C2, potently inhibited platelet aggregation induced by ADP, thrombin, arachidonic acid, collagen, U46619, adrenaline and platelet-activating factor, whereas ristocetin-induced aggregation was unaffected. MA-16N7C2 (IgG2a) bound approximately 4 times faster to activated than to resting platelets, with a Kdcalc of 6.6nM and of 17.5nM, respectively. Equilibrium binding studies to non-activated platelets showed a Kd of 18.2nM with 41 x 10(3) binding sites per platelet. The antibody recognized GPIIb/IIIa only as a Ca(2+)-dependent complex. MA-16N7C2 blocked fibrinogen and von Willebrand factor binding to GPIIb/IIIa in a competitive manner with a Ki of 8.5nM and 13.2nM, respectively. Sequence analysis revealed a RGD-containing sequence with homology to disintegrins, in the CDR3 region of the heavy chain. That this RGD-containing sequence could be involved in the interaction of the antibody to GPIIb/IIIa was finally indicated by showing that the binding is completely and competitively inhibited by echistatin.

Synergistic antiplatelet effect of ridogrel, a combined thromboxane receptor antagonist and thromboxane synthase inhibitor, and UDCG-212, a cAMP-phosphodiesterase inhibitor

Ridogrel, a combined thromboxane receptor antagonist and thromboxane synthase inhibitor (1), inhibits platelet aggregation. Following stimulation with arachidonic acid, cAMP-levels are increased in human platelets preincubated with ridogrel, this is due to the known reorientation of the metabolism of the formed endoperoxides towards adenylate cyclase stimulating prostaglandins. Pretreatment of resting platelets with UDCG-212, a cAMP-phosphodiesterase inhibitor (2), also inhibits platele aggregation induced by arachidonic acid, concomitant with an increase in cAMP levels, due to an inhibition of its breakdown. Under basal conditions, cAMP also is increased. By combining the two drugs, a more than additive action was observed on platelet aggregation and on both resting and stimulated platelet cAMP content. The appropriate combination may result in a more effective antiplatelet strategy.

Biologic effects of recombinant hirudin (CGP 39393) in human volunteers. European Hirudin in Thrombosis Group

OBJECTIVES

The purpose of this study was to investigate the biologic efficacy and pharmacokinetics of different doses of recombinant hirudin administered in single or repeated subcutaneous injections in healthy volunteers.

BACKGROUND

Hirudin is a highly specific inhibitor of thrombin, the pivotal enzyme in thrombosis. Differences between hirudin and heparin in experimental animals indicate that hirudin may be a superior antithrombotic drug in humans.

METHODS

The biologic effect of recombinant desulfato-hirudin (CGP 39393) administered as single or repeated (every 8 h for 3 days or every 12 h for 6 days) subcutaneous injections was studied in 231 healthy human volunteers.

RESULTS

Single subcutaneous doses of 0.1, 0.2, 0.3, 0.4, 0.5 and 0.75 mg/kg body weight in 195, 8, 12, 8, 4 and 4 volunteers, respectively, prolonged the activated partial thromboplastin time in a dose-proportional fashion within the 1st 30 min, with a near-maximal effect for 3 to 4 h after the dose. The mean activated partial thromboplastin time increased to 1.48 and 1.93 times baseline values 30 min after single subcutaneous injections of 0.2 and 0.4 mg/kg of CGP 39393, respectively. There was a linear relation over a wide range between the activated partial thromboplastin time prolongation and plasma concentrations of CGP 39393. Plasma clearance was between 1.5 and 1.7 ml/min per kg. The subcutaneous administration of 0.3 and 0.5 mg recombinant hirudin three times a day for 3 days or two times a day for 6 days prolonged the activated partial thromboplastin time by 1.71 to 1.69 and 1.78 to 1.92 times baseline levels, respectively, with the preinjection values maintained in the hypocoagulable range. No prolongation of bleeding time was measured at peak plasma hirudin levels. Because thrombin and prothrombin times are not able to reflect high or low CGP 39393 concentrations, respectively, neither test is suitable for monitoring administration of this drug.

CONCLUSIONS

CGP 39393 appears to be well tolerated in volunteers, even after repeated doses. The activated partial thromboplastin time test seems to be well suited to monitor the anticoagulant effect of recombinant hirudin because the dose effect is linear up to 0.5 mg/kg of subcutaneous CGP 39393. The prolongation of activated partial thromboplastin time after subcutaneous injection of CGP 39393 shows a plateau lasting for 3 h. Further studies are now required to determine the dose that will provide the best antithrombotic effect and the lowest bleeding tendency in arterial or venous thrombosis indications.

Clinical pharmacology of intravenously administered recombinant desulfatohirudin (CGP 39393) in healthy volunteers

Clinical pharmacology of the intravenously administered recombinant desulfatohirudin CGP 39393 was investigated in 47 healthy volunteers in a multicenter study. Mean peak concentrations after bolus injections of 0.1, 0.3, 0.5, and 1.0 mg/kg were 154, 443, 764, and 1,691 nmol/L, respectively. Intravenous infusions of 0.1 mg/kg/h for 6 h and of 0.2 and 0.3 mg/kg/h for 6 h and 72 h resulted in mean steady-state levels of 78, 227, and 312 nmol/L. Elimination was multiexponential and dose independent. Concordant pharmacokinetic parameters were obtained from both i.v. bolus and infusion experiments (overall average total plasma clearance, 2.20 ml/min/kg; mean residence time, 2.12 h; volume at steady state, 0.27 L/kg). Thrombin inhibition by CGP 39393 was demonstrated ex vivo by the thrombin chromogenic assay (TCA), by activated partial thromboplastin time (APTT), thrombin time (TT), and prothrombin time (PT). Following a parabolic function APTT doubled and quadrupled at CGP 39393 concentrations of 100 and 1,000 nmol/L, respectively. Whereas TTs (bovine thrombin 3 or 6 IU/ml) were very sensitive to low CGP 39393 levels with unmeasurable clotting times at CGP 39393 concentrations greater than 30 and 60 nmol/L, PT was prolonged by a factor of only 1.3 above baseline at 300 nmol/L. APTT appears to be most suitable for monitoring the anticoagulant effect of CGP 39393 over a broad concentration range. The drug was well tolerated without clinically relevant bleeding episodes or other adverse events.

Grey platelet syndrome: evidence for alpha-granule localization of the platelet plasminogen activator inhibitor-1 pool

The case of an 11-year-old boy with grey platelet syndrome is described. Platelets had the typical grey and ghostly appearance on May-Grünwald/Giemsa staining, caused by the absence of alpha granules confirmed by electron microscopy. Alpha granule protein content, i.e., beta-thromboglobulin and platelet factor 4, was less than 3% of normal and alpha granule secretion in response to thrombin was not detectable photometrically. The plasminogen activator inhibitor-1 pool in the patient's platelets was 5% of normal, confirming previous indirect evidence for the storage of this protein within the alpha-granule. Dense body secretion of adenosine triphosphate and 5-hydroxytryptamine was normal. Aggregation occurred normally in response to adenosine diphosphate and there was a slight delay in response to collagen.