Multi-dose vials versus single-dose vials for vaccination: perspectives from lower-middle income countries

Maximizing doses from multi-dose vaccine vials using the air bubble trapping technique

Purpose

Vaccine shortages present significant challenges for public health, necessitating strategies such as fractional dosing and the use of adjuvants to conserve doses. However, reducing vaccine wastage remains essential. One approach is the air bubble trapping technique (ABTT), which involves trapping an air bubble to minimize dead volume loss and maximize the number of doses extracted from multi-dose vials.

Materials and Methods

This study compares ABTT with standard methods using 3 syringe types. Healthcare workers prepared 0.1 mL and 0.5 mL saline doses both with and without ABTT.

Results

Results showed that ABTT produced comparable vaccine volumes to conventional techniques but required extra preparation time. ABTT reduced volume by 8.6% for 0.1 mL doses and 2.9% for 0.5 mL doses, with preparation times of 30.63 and 32.95 seconds, compared to 12.53 and 15.11 seconds without ABTT.

Conclusion

ABTT was consistent across different syringe types and levels of user experience, allowing for practical integration into vaccination workflows.

Development of multidose thermotolerant formulations of a vector-based Covid-19 vaccine candidate, NDV-HXP-S in different product formats: Stability and preservative efficacy study

Current lead coronavirus vaccines require continuous cold or ultra-cold storage from the manufacturing site to the field to maintain protective efficacy. Since cold chain capacity is limited and complex, logistics planning is crucial to limit vaccine wastage.[1] The restrictive storage concerns also make it difficult to share vaccines between public health departments and neighboring states, leading to increased vaccine wastage.[2] A Newcastle Disease Virus (NDV) vector-based severe acute respiratory syndrome coronavirus 2 (SARS CoV-2) vaccine candidate, NDV-HXP-S, offers a cost-effective alternative which aims to improve global access to SARS CoV-2 vaccines.[3] The NDV-HXP-S vaccine candidate can be mass-produced in chicken eggs and has demonstrated efficacy in preclinical studies, as well as acceptable safety and potent immunogenicity in clinical studies.[3,4-10] To further advance the NDV-HXP-S vaccine candidate, this manuscript describes work focused on the development of multidose thermotolerant vaccine formulations (i.e., those which would not require continuous extended refrigeration), making it convenient to use and store, and simplifying transport and distribution logistics, especially in outbreak settings. Liquid and lyophilized formulations for parenteral administration were rigorously screened for the vaccine formulation's ability to maintain S-antigen stability after exposure to temperature stress at 40 °C, 25 °C, and 2 °C to 8 °C storage for six months. Preservative efficacy was evaluated to enable a multidose liquid vaccine format as well as endotoxin testing in lyophilized formulations. Lead liquid vaccine formations were identified that were able to maintain S-antigen content at 2 °C to 8 °C and 25 °C storage for the entire six-month study. Lead lyophilized vaccine formulations were identified which were able to maintain S-antigen content for six months at 2 °C to 8 °C, 25 °C, and 40 °C. Both the liquid and lyophilized formulations identified are improved thermotolerant SARS-CoV-2 vaccine formulations.

Improving vaccine equity by increasing vaccine thermostability

The development, manufacture, and deployment of new vaccine technologies to combat SARS-CoV-2 enabled an unparalleled rapid response to the emerging health threat. However, the unequal global distribution of these vaccines highlighted a major gap in existing thermotolerance profiles and cold chain infrastructure that needs to be addressed to maximize their global health impact.

Respiratory Syncytial Virus (RSV) Disease and Prevention Products: Knowledge, Attitudes, and Preferences of Kenyan Healthcare Workers in Two Counties in 2021

Respiratory syncytial virus (RSV) is a major cause of lower respiratory tract infection (LRTI) among infants under 6 months of age. Yet, in Kenya, little is known about healthcare workers' (HCWs) knowledge, attitudes, and perceptions around RSV disease and the prevention products under development. Between September and October 2021, we conducted a mixed methods cross-sectional survey to assess HCWs' knowledge, attitudes, and perceptions of RSV disease and RSV vaccinations in two counties. We enrolled HCWs delivering services directly at maternal and child health (MCH) departments in selected health facilities (frontline HCWs) and health management officers (HMOs). Of the 106 respondents, 94 (88.7%) were frontline HCWs, while 12 were HMOs. Two of the HMOs were members of the Kenya National Immunization Technical Advisory Group (KENITAG). Of the 104 non-KENITAG HCWs, only 41 (39.4%) had heard about RSV disease, and 38/41 (92.7%) felt that pregnant women should be vaccinated against RSV. Most participants would recommend a single-dose vaccine schedule (n = 62, 58.5%) for maximal adherence and compliance (n = 38/62, 61.3%), single dose/device vaccines (n = 50/86, 58.1%) to prevent wastage and contamination, and maternal vaccination through antenatal care clinics (n = 53, 50%). We found the need for increased knowledge about RSV disease and prevention among Kenyan HCWs.