Molecular characterization of the 17D-204 yellow fever vaccine

IntroductionThe worldwide use of yellow fever (YF) live attenuated vaccines came recently under close scrutiny as rare but serious adverse events have been reported. The population identified at major risk for these safety issues were extreme ages and immunocompromised subjects. Study NCT01426243 conducted by the French National Agency for AIDS research is an ongoing interventional study to evaluate the safety of the vaccine and the specific immune responses in HIV-infected patients following 17D-204 vaccination. As a preliminary study, we characterized the molecular diversity from E gene of the single 17D-204 vaccine batch used in this clinical study.Materials and methodsEight vials of lyophilized 17D-204 vaccine (Stamaril^®, Sanofi-Pasteur, Lyon, France) of the E5499 batch were reconstituted for viral quantification, cloning and sequencing of C/prM/E region.ResultsThe average rate of virions per vial was 8.68 ± 0.07 log₁₀ genome equivalents with a low coefficient of variation (0.81%). 246 sequences of the C/prM/E region (29–33 per vials) were generated and analyzed for the eight vials, 25 (10%) being defective and excluded from analyses. 95% of sequences had at least one nucleotide mutation. The mutations were observed on 662 variant sites distributed through all over the 1995 nucleotides sequence and were mainly non-synonymous (66%). Genome variability between vaccine vials was highly homogeneous with a nucleotide distance ranging from 0.29% to 0.41%. Average p-distances observed for each vial were also homogeneous, ranging from 0.15% to 0.31%.ConclusionThis study showed a homogenous YF virus RNA quantity in vaccine vials within a single lot and a low clonal diversity inter and intra vaccine vials. These results are consistent with a recent study showing that the main mechanism of attenuation resulted in the loss of diversity in the YF virus quasi-species.     

The effect of cool water pack preparation on vaccine vial temperatures in refrigerators

Cool water packs are a useful alternative to ice packs for preventing unintentional freezing of vaccines during outreach in some situations. Current guidelines recommend the use of a separate refrigerator for cooling water packs from ambient temperatures to prevent possible heat degradation of adjacent vaccine vials. To investigate whether this additional equipment is necessary, we measured the temperatures that vaccine vials were exposed to when warm water packs were placed next to vials in a refrigerator. We then calculated the effect of repeated vial exposure to those temperatures on vaccine vial monitor status to estimate the impact to the vaccine. Vials were tested in a variety of configurations, varying the number and locations of vials and water packs in the refrigerator. The calculated average percentage life lost during a month of repeated warming ranged from 20.0% to 30.3% for a category 2 (least stable) vaccine vial monitor and from 3.8% to 6.0% for a category 7 (moderate stability) vaccine vial monitor, compared to 17.0% for category 2 vaccine vial monitors and 3.1% for category 7 vaccine vial monitors at a constant 5 °C. The number of vials, number of water packs, and locations of each impacted vial warming and therefore percentage life lost, but the vaccine vial monitor category had a higher impact on the average percentage life lost than any of the other parameters. The results suggest that damage to vaccines from repeated warming over the course of a month is not certain and that cooling water packs in a refrigerator where vaccines are being stored may be a useful practice if safe procedures are established.     

The value of tailoring vial sizes to populations and locations

Background

Frequently, a country will procure a single vaccine vial size, but the question remains whether tailoring the use of different size vaccine vial presentations based on populations or location characteristics within a single country could provide additional benefits, such as reducing open vial wastage (OVW) or reducing missed vaccination opportunities.

The budget impact of controlling wastage with smaller vials: A data driven model of session sizes in Bangladesh,India (Uttar Pradesh), Mozambique,and Uganda

Introduction

Open vial vaccine wastage in multi-dose vials is a major contributor to vaccine wastage. Although switching from 10-dose vials to 5-dose vials could reduce wastage, a higher total cost could be triggered because smaller vials cost more to purchase and store.

Methods

This study drew field data of daily session sizes in local vaccination facilities from Bangladesh, India (Uttar Pradesh), Mozambique, and Uganda, and used Akaike Information Criteria to determine the best fit statistical distribution across various clinic types. These distributions were input to estimate the vaccine wastage using Lee's (2010) model. Inactivated polio vaccine (IPV) immunization was simulated to compare the costs over ten years with 10-dose vials versus 5-dose vials.

Results

By switching from 10- to 5-dose vials, the observed open vial wastage rate due to vial size preference and session size for IPV was reduced from 0.25 to 0.11 in Bangladesh, 0.17 to 0.08 in India (Uttar Pradesh), 0.13 to 0.06 in Mozambique, and 0.09 to 0.04 in Uganda, respectively. The cost savings realized from lower IPV wastage did not offset the higher costs of procurement and storage costs associated with smaller dose presentation.

Conclusion

While our model showed that switching from 10-dose vials to 5-dose vials of IPV reduced open vial wastage, it was not cost-saving.     

Decision making process,programmatic and logistic impact of the transition from a single-dose vial to a multi-dose vial of the 13-valent pneumococcal vaccine in Benin

BackgroundBenin, a country eligible for Gavi support, changed the presentation of the 13-valent pneumococcal vaccine (PCV13) from the single-dose vial (SDV) to the multi-dose vial (MDV). The present work aims to evaluate the process of making this decision as well as programmatic and logistic impacts.MethodsWHO protocol for post-introduction evaluation (PIE) was used. Programmatic impact was evaluated by comparing PCV13 coverage and dropout rates with a comparator vaccine administered simultaneously over similar 6-month periods prior to and after the transition. This impact was also appreciated from observation of multi-dose vial management practices during immunization sessions. Logistic impact was measured from the analysis of storage capacities, waste management and vaccine losses.ResultsDecision to move to PCV13 MDV was taken at EPI level. Activities planned to support this switch were partially implemented.Impact on vaccination coverage and PCV13 dropout rates in relation with the transition to PCV13 MDV was not detected. The study found that 63% of the health staff surveyed knew and applied WHO's multidose vial policy (MDVP). Vaccines opened vials were found in 83% of health facilities visited. PCV13 MDV (37%) was one of the 3 main vaccines found with open vials in health facility refrigerators. Vaccination risky practices were observed during immunization sessions in 83% of health facilities. The main risky practice was the lack of indication of the date and hour of opening vials (56%).There was a reduction of the volume occupied by vaccines at central store by 47%. Net storage volume per fully immunized child (FIC) decreased from 69.5 to 41 m³. PCV13 MDV allows for 40% reduction in the amount of waste produced by vaccination. PCV13 open vial loss rate has increased from 3 to 7%.ConclusionBenin’s experience in transition to an MDV presentation of PCV13 reveals the need for better preparation and planning.     

Variability of in vivo potency assays of whole-cell pertussis,inactivated polio,and meningococcal B vaccines

For the batch release of vaccines, potency release assays are required. Non-animal in vitro tests have numerous advantages and are preferred; however, several vaccines are still released using in vivo assays. Their major drawback is the inherent variability with its practical implications. We quantified the variability of in vivo potency release assays for whole-cell pertussis, inactivated polio and meningococcal B (MenB) vaccines which showed large CV (Coefficient of Variation) ranging from 34% to 125%. As inherent variability might potentially be attributed to the highly variable immune system between individual animals, we evaluated the antibody titres to four MenB antigens in 344 individual outbred mice. These varied strongly, with more than 100-fold differences in antibody titres in responsive mice. Furthermore, within individual mice there was generally no correlation between the strengths of the responses to the four antigens. A mouse with a very low or no response to one antigen in many cases exhibited a strong response to another antigen. The large differences between individual animals is likely a considerable contributor to the inherent variability of in vivo potency assays. Our data again support the notion that it is preferred to move away from in vivo potency assays for monitoring batch to batch consistency as part of vaccine batch release testing.     

Using oral polio vaccine beyond the cold chain: A feasibility study conducted during the national immunization campaign in Mali

We conducted the first systematic documentation of using oral polio vaccine (OPV) out of the cold chain during national immunization day (NID) campaigns in Mali. Using a crossover intervention design, vaccinators compared the transport of OPV in vaccine carriers with or without ice packs. Vaccine integrity was assured through monitoring vaccine vial monitor (VVM) status. Despite ambient temperatures up to 40 °C, none of the VVMs on any of the vials used (n = 956) reached their discard point. Over 90% of vaccinators and supervisors preferred conducting NIDs without ice packs. In addition, using OPV out of the cold chain reduced vaccine wastage resulting from melting ice packs causing labels to detach from the vial.     

Replacing the measles ten-dose vaccine presentation with the single-dose presentation in Thailand

Introduced to minimize open vial wastage, single-dose vaccine vials require more storage space and therefore may affect vaccine supply chains (i.e., the series of steps and processes involved in distributing vaccines from manufacturers to patients). We developed a computational model of Thailand's Trang province vaccine supply chain to analyze the effects of switching from a ten-dose measles vaccine presentation to each of the following: a single-dose measles-mumps-rubella vaccine (which Thailand is currently considering) or a single-dose measles vaccine. While the Trang province vaccine supply chain would generally have enough storage and transport capacity to accommodate the switches, the added volume could push some locations’ storage and transport space utilization close to their limits. Single-dose vaccines would allow for more precise ordering and decrease open vial waste, but decrease reserves for unanticipated demand. Moreover, the added disposal and administration costs could far outweigh the costs saved from preventing open vial wastage.     

Modular vaccine packaging increases packing efficiency

BackgroundWithin a typical vaccine supply chain, vaccines are packaged into individual cylindrical vials (each containing one or more doses) that are bundled together in rectangular “inner packs” for transport via even larger groupings such as cold boxes and vaccine carriers. The variability of vaccine inner pack and vial size may hinder efficient vaccine distribution because it constrains packing of cold boxes and vaccine carriers to quantities that are often inappropriate or suboptimal in the context of country-specific vaccination guidelines.MethodsWe developed in Microsoft Excel (Microsoft Corp., Redmond, WA) a spreadsheet model that evaluated the impact of different packing schemes for the Benin routine regimen plus the introduction of the Rotarix vaccine. Specifically, we used the model to compare the current packing scheme to that of a proposed modular packing scheme.ResultsConventional packing of a Dometic RCW25 that aims to maximize fully-immunized children (FICs) results in 123 FICs and a packing efficiency of 81.93% compared to a maximum of 155 FICs and 94.1% efficiency for an alternative modular packaging system.ConclusionsOur analysis suggests that modular packaging systems could offer significant advantages over conventional vaccine packaging systems with respect to space efficiency and potential FICs, when they are stored in standard vaccine carrying devices. This allows for more vaccines to be stored within the same volume while also simplifying the procedures used by field workers to pack storage devices. Ultimately, modular packaging systems could be a simple way to help increase vaccine coverage worldwide.     

The effects of switching from 10 to 5-dose vials of MR vaccine on vaccination coverage and wastage: A mixed-method study in Zambia

IntroductionVaccines procured for low-income countries are often packaged in multi-dose vials to reduce program costs. To avoid wastage, health workers may refrain from opening a vial if few children attend an immunization session, possibly leading to lower coverage. Lowering the number of doses in a vial may increase coverage and reduce wastage.MethodsWe used a mixed methods approach to measure the effects of switching from conventional 10-dose measles containing vaccine (MCV) vials to 5-dose MCV vials on coverage and open vial wastage in 14 districts purposely selected from two provinces in Zambia. The districts were paired based on the number of health facilities and the average size of the health facility catchment population. One district from each pair was randomly allocated to receive 5-dose vials while the other continued with the conventional vials. We applied propensity score matched difference-in-difference analysis to estimate intervention effects on coverage using pre-intervention household survey and post-intervention household survey after 11 months of the intervention. The intervention effects on wastage rates were estimated from multivariate analysis of the administrative data. Key informant interviews were conducted to better understand health workers’ behavior and preferences at baseline, midline and endline, and analyzed using thematic analysis techniques.ResultsMCV coverage rates increased across both arms for both doses. A five percentage-point intervention effect was detected for MCV1 and 3.5 percentage-point effect for MCV2. The MCV wastage rate was 47% lower in facilities using 5-dose vials (16.2%) versus 10-dose vials (30.5%). Healthcare workers reported being more willing to open a 5-dose vial than a 10-dose vial for one child, as they were less concerned about wastage.DiscussionSwitching 10-dose MCV vials to 5-dose vials improved coverage, decreased wastage, and improved willingness to open a vial. These findings can contribute to strategies for reducing missed opportunities for vaccination.     

Vaccine wastage in Ghana,Mozambique, and Pakistan: An assessment of wastage rates for four vaccines and the context,causes, drivers,and knowledge,attitudes and practices for vaccine wastage

Vaccine procurement costs comprise a significant share of immunization program costs in low- and middle-income countries, yet not all procured vaccines are administered. Vaccine wastage occurs due to vial breakage, excessive heat or freezing, expiration, or when not all doses in a multidose vial are used. Better estimates of vaccine wastage rates and their causes could support improved management of vaccine stocks and reduce procurement costs. This study examined aspects of wastage for four vaccines at service delivery points in Ghana (n = 48), Mozambique (n = 36), and Pakistan (n = 46). We used prospective data from daily and monthly vaccine usage data entry forms, along with cross-sectional surveys, and in-depth interviews. The analysis found that estimated monthly proportional open-vial wastage rates for vaccines in single-dose vials (SDV) or in multi-dose vials (MDV) that can be kept refrigerated up to four weeks after opening ranged from 0.08 % to 3 %. For MDV where remaining doses are discarded within six hours after opening, the mean wastage rates ranged from 5 % to 33 %, with rates being highest for measles containing vaccine. Despite national-level guidance to open a vaccine vial even when only one child is present, vaccines in MDV that are discarded within six hours of opening are sometimes offered less frequently than vaccines in SDV or in MDV where remaining doses can be used for up to 4 weeks. This practice can lead to missed opportunities for vaccination. While closed-vial wastage at service delivery points (SDPs) was relatively rare, individual instances can result in large losses, suggesting that monitoring closed-vial wastage should not be neglected. Health workers reported insufficient knowledge of vaccine wastage tracking and reporting methods. Improving reporting forms would facilitate more accurate reporting of all causes of wastage, as would additional training and supportive supervision. Globally, decreasing doses per vial could reduce open-vial wastage.     

Single-dose versus multi-dose vaccine vials for immunization programmes in developing countries

Excessive vaccine wastage and safety concerns have prompted the international health community to develop and supply vaccines in formats other than the standard multi-dose vial. This article presents a programmatic and economic comparison of the major differences between the multi-dose vials and single-dose formats used for immunization services in developing countries. Multi-dose vials, in general, sell at a lower per-dose price and occupy less cold-chain capacity than single-dose formats. However, higher wastage rates may offset these benefits, especially for more expensive vaccines. Single-dose formats offer several important programmatic benefits, such as increased vaccination opportunities and improved vaccine safety. One single-dose format, the prefilled auto-disable (AD) device, provides additional injection safety and convenience features because it physically combines the vaccine and AD syringe. Selecting the appropriate vaccine presentation will depend on many factors. However, multi-dose vials are likely to be most appropriate for cheaper vaccines and in settings where cold-chain storage capacity is restricted. Single-dose formats will be most appropriate for more expensive vaccines and where there are problems with unsafe injection practices. Prefilled AD injection devices will be particularly useful in expanding outreach services while eliminating the possibility of needle reuse.     

Dual-chamber injection device for measles-rubella vaccine: The potential impact of introducing varying sizes of the devices in 3 countries

IntroductionBy pairing diluent with vaccines, dual-chamber vaccine injection devices simplify the process of reconstituting vaccines before administration and thus decrease associated open vial wastage and adverse events. However, since these devices are larger than current vaccine vials for lyophilized vaccines, manufacturers need guidance as to how the size of these devices may affect vaccine distribution and delivery.MethodsUsing HERMES-generated immunization supply chain models of Benin, Bihar (India), and Mozambique, we replace the routine 10-dose measles-rubella (MR) lyophilized vaccine with single-dose MR dual-chamber injection devices, ranging the volume-per-dose (5.2–26 cm³) and price-per-dose ($0.70, $1.40).ResultsAt a volume-per-dose of 5.2 cm³, a dual-chamber injection device results in similar vaccine availability, decreased open vial wastage (OVW), and similar total cost per dose administered as compared to baseline in moderately constrained supply chains. Between volumes of 7.5 cm³ and 26 cm³, these devices lead to a reduction in vaccine availability between 1% and 14% due to increases in cold chain storage utilization between 1% and 7% and increases in average peak transport utilization between 2% and 44%. At the highest volume-per-dose, 26 cm³, vaccine availability decreases between 9% and 14%. The total costs per dose administered varied between each scenario, as decreases in vaccine procurement costs were coupled with decreases in doses administered. However, introduction of a dual-chamber injection device only resulted in improved total cost per dose administered for Benin and Mozambique (at 5.2 cm³ and $0.70-per-dose) when the total number of doses administered changed <1% from baseline.ConclusionIn 3 different country supply chains, a single-dose MR dual-chamber injection device would need to be no larger than 5.2 cm³ to not significantly impair the flow of other vaccines.     

Assessment of vaccine wastage rates,missed opportunities,and related knowledge,attitudes and practices during introduction of a second dose of measles-containing vaccine into Cambodia’s national immunization program

IntroductionMissed opportunities for vaccination (MOV) can result in inadequate protection against disease. Although healthcare provider reluctance to open multi-dose, lyophilized vaccine vials (particularly the measles-containing vaccine [MCV]) for every eligible child due to concerns about wasting vaccine is a known reason for MOV, little is known about providers’ related attitudes and practices.MethodsIn 100 randomly selected health facilities and 24 districts of Cambodia, we surveyed healthcare providers and their district supervisors regarding routine vaccine administration and wastage knowledge and practices, and child caregivers (five per facility) regarding MOV. Vaccine stock management data covering six months were reviewed to calculate facility and district level wastage rates and vaccine usage patterns for six vaccines, including a recently introduced second dose of MCV (MCV2).ResultsResponse rates were 100/100 (100%) among facility staff, 48/48 (100%) among district staff, and 436/500 (87%) among caregivers. Mean facility-level wastage rates varied from 4% for single-dose diphtheria-tetanus-pertussis-hepatitis B-Haemophilus influenzae type b vaccine to 60% for 10-dose MCV; district-level wastage rates for all vaccines were 0%. Some vaccines had lower wastage rates in large facilities compared to small facilities. The mean MCV wastage rate was the same before and immediately after MCV2 introduction. Providers reported waiting for a mean of two children prior to opening an MCV vial, and 71% of providers reported offering MCV vaccination less frequently during scheduled vaccination sessions than other vaccines. Less than 5% of caregivers reported that their child had been turned away for vaccination, most frequently (65%) for MCV.DiscussionAlthough the MCV wastage rate in our study was in line with national targets, providers reported waiting for more than one child before opening an MCV vial, contrary to vaccine management guidelines. Future research should explore the causal links between provider practices related to vaccine wastage and their impact on vaccination coverage.     

Vial usage,device dead space,vaccine wastage,and dose accuracy of intradermal delivery devices for inactivated poliovirus vaccine (IPV)

IntroductionIntradermal delivery of a fractional dose of inactivated poliovirus vaccine (IPV) offers potential benefits compared to intramuscular (IM) delivery, including possible cost reductions and easing of IPV supply shortages. Objectives of this study were to assess intradermal delivery devices for dead space, wastage generated by the filling process, dose accuracy, and total number of doses that can be delivered per vial.MethodsDevices tested included syringes with staked (fixed) needles (autodisable syringes and syringes used with intradermal adapters), a luer-slip needle and syringe, a mini-needle syringe, a hollow microneedle device, and disposable-syringe jet injectors with their associated filling adapters. Each device was used to withdraw 0.1-mL fractional doses from single-dose IM glass vials which were then ejected into a beaker. Both vial and device were weighed before and after filling and again after expulsion of liquid to record change in volume at each stage of the process. Data were used to calculate the number of doses that could potentially be obtained from multidose vials.ResultsResults show wide variability in dead space, dose accuracy, overall wastage, and total number of doses that can be obtained per vial among intradermal delivery devices. Syringes with staked needles had relatively low dead space and low overall wastage, and could achieve a greater number of doses per vial compared to syringes with a detachable luer-slip needle. Of the disposable-syringe jet injectors tested, one was comparable to syringes with staked needles.DiscussionIf intradermal delivery of IPV is introduced, selection of an intradermal delivery device can have a substantial impact on vaccine wasted during administration, and thus on the required quantity of vaccine that needs to be purchased. An ideal intradermal delivery device should be not only safe, reliable, accurate, and acceptable to users and vaccine recipients, but should also have low dead space, high dose accuracy, and low overall wastage to maximize the potential number of doses that can be withdrawn and delivered.     

One size does not fit all: The impact of primary vaccine container size on vaccine distribution and delivery

BackgroundWhile the size and type of a vaccine container (i.e., primary container) can have many implications on the safety and convenience of a vaccination session, another important but potentially overlooked consideration is how the design of the primary container may affect the distribution of the vaccine, its resulting cost, and whether the vial is ultimately opened.MethodsUsing our HERMES software platform, we developed a simulation model of the World Health Organization Expanded Program on Immunization supply chain for the Republic of Benin and used the model to explore the effects of different primary containers for various vaccine antigens.ResultsReplacing vaccines with presentations containing fewer doses per vial reduced vaccine availability (proportion of people arriving for vaccines who are successfully immunized) by as much as 13% (from 73% at baseline) and raised logistics costs by up to $0.06 per dose administered (from $0.25 at baseline) due to increased bottlenecks, while reducing total costs by as much as $0.15 per dose administered (from $2.52 at baseline) due to lower open vial wastage. Primary containers with a greater number of doses per vial each improved vaccine availability by 19% and reduced logistics costs by $0.05 per dose administered, while reducing the total costs by up to $0.25 per dose administered. Changes in supply chain performance were more extreme in departments with greater constraints. Implementing a vial opening threshold reversed the direction of many of these effects.ConclusionsOur results show that one size may not fit all when choosing a primary vaccine container. Rather, the choice depends on characteristics of the vaccine, the vaccine supply chain, immunization session size, and goals of decision makers. In fact, the optimal vial size may vary among locations within a country. Simulation modeling can help identify tailored approaches to improve availability and efficiency.     

新疆维吾尔自治区2016－2017年免疫规划疫苗损耗调查

目的 了解新疆维吾尔自治区预防接种单位免疫规划（EPI）疫苗的损耗现状，为进一步精细化管理和使用EPI疫苗提供依据。方法 采取分层整群抽样方法抽取135个接种单位，调查2016-2017年6种EPI疫苗接种和使用数据，包括常规免疫和脊髓灰质炎疫苗群体性补充免疫活动中疫苗领发和使用数量、疫苗报废记录，以及接种单位的地区类型、服务模式、接种周期、日均接种量等。采用描述流行病学方法计算和分析疫苗的损耗系数。结果 单人份的无细胞百白破联合疫苗（DTaP）和三价脊髓灰质炎减毒活疫苗（tOPV）损耗系数最低，分别为1.00和1.02；多人份的二价脊髓灰质炎减毒活疫苗（bOPV）、A群脑膜炎球菌多糖疫苗（MPV-A）、白喉破伤风联合疫苗（DT）、卡介苗（BCG）损耗系数分别为1.58、1.67、1.68、3.02。城市、农村、牧区接种单位EPI疫苗损耗系数范围分别为1.00~2.84、1.00~3.71、1.00~2.27；乡级集中、村级集中、分散接种模式的损耗系数分别为1.00~3.00、1.00~4.41、1.00~1.94。接种周期越长或日均接种量越小，损耗系数越大。结论 新疆维吾尔自治区预防接种单位多人份EPI疫苗损耗较高，并受地区和接种服务形式的影响。需根据地区类型、接种单位服务形式等加强精细化的疫苗管理，减少疫苗损耗和浪费。     

Single-vial filovirus glycoprotein vaccines: Biophysical characteristics and immunogenicity after co-lyophilization with adjuvant

Zaire ebolavirus (EBOV), Sudan ebolavirus (SUDV), and Marburg marburgvirus (MARV) are the most prevalent and pathogenic species of filovirus. Previously, we showed that glycoprotein antigens from each virus could be lyophilized to create thermostable monovalent subunit vaccines. However, cross-protection is not expected from the monovalent vaccines and therefore developing a trivalent filovirus vaccine would be desirable. Subunit protein vaccines often require the addition of an adjuvant to sufficiently boost the immunogenicity. Typically, liquid suspensions or emulsions of adjuvants and lyophilized antigens are stored in separate vials to avoid destabilizing interactions and are only mixed immediately before administration. Herein, we describe the development and characterization of monovalent and trivalent filovirus vaccines that are co-lyophilized with a squalane-in-water emulsion adjuvant. We found that the single-vial presentation retained adjuvant particle diameter and zeta potential after lyophilization and reconstitution. Furthermore, the trivalent vaccines elicited high antibody levels against all three antigens in mice and non-human primates. These results advance the prospect of developing a single-vial trivalent filovirus vaccine, which would enable easier distribution and administration of the vaccine to resource-poor areas.     

Technical product attributes in development of an oral enteric vaccine for infants

Development of an oral enteric vaccine for infants is important for Shigella and enterotoxigenic Escherichia coli (ETEC) vaccine development. At a recent workshop titled “Technical Product Attributes in Development of an Oral Enteric Vaccine for Infants,” at the 2nd International Vaccines Against Shigella and ETEC Conference (VASE Conference), the preferred product attributes for development were discussed for these vaccines. The aims of this workshop were to identify gaps and gather opinions from key experts from preclinical, process development, manufacturing, regulatory, and clinical areas to fine-tune and refine key target product attributes for infant oral vaccine development. The workshop used some examples of marketed oral infant vaccines to discuss potential improvements that can be made, such as inclusion of preservatives, multidose vials, and antacid buffer presentation (liquid or lyophilized) in novel oral enteric vaccine development.     

Freeze-thaw stress of Alhydrogel alone is sufficient to reduce the immunogenicity of a recombinant hepatitis B vaccine containing native antigen

Preventing losses in vaccine potency due to accidental freezing has recently become a topic of interest for improving vaccines. All vaccines with aluminum-containing adjuvants are susceptible to such potency losses. Recent studies have described excipients that protect the antigen from freeze-induced inactivation, prevent adjuvant agglomeration and retain potency. Although these strategies have demonstrated success, they do not provide a mechanistic understanding of freeze–thaw (FT) induced potency losses. In the current study, we investigated how adjuvant frozen in the absence of antigen affects vaccine immunogenicity and whether preventing damage to the freeze-sensitive recombinant hepatitis B surface antigen (rHBsAg) was sufficient for maintaining vaccine potency. The final vaccine formulation or Alhydrogel^® alone was subjected to three FT-cycles. The vaccines were characterized for antigen adsorption, rHBsAg tertiary structure, particle size and charge, adjuvant elemental content and in-vivo potency. Particle agglomeration of either vaccine particles or adjuvant was observed following FT-stress. In vivo studies demonstrated no statistical differences in IgG responses between vaccines with FT-stressed adjuvant and no adjuvant. Adsorption of rHBsAg was achieved; regardless of adjuvant treatment, suggesting that the similar responses were not due to soluble antigen in the frozen adjuvant-containing formulations. All vaccines with adjuvant, including the non-frozen controls, yielded similar, blue-shifted fluorescence emission spectra. Immune response differences could not be traced to differences in the tertiary structure of the antigen in the formulations. Zeta potential measurements and elemental content analyses suggest that FT-stress resulted in a significant chemical alteration of the adjuvant surface. This data provides evidence that protecting a freeze-labile antigen from subzero exposure is insufficient to maintain vaccine potency. Future studies should focus on adjuvant protection. To our knowledge, this is the first study to systematically investigate how FT-stress to adjuvant alone affects immunogenicity. It provides definitive evidence that this damage is sufficient to reduce vaccine potency.