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An Introduction to the Immune System and Vaccines
Published in Patricia G. Melloy, Viruses and Society, 2023
The ultimate goal of any vaccination campaign is to remove the pathogen from the human population. Smallpox was eradicated in 1980 after approximately 3,000 years of being a scourge of the planet (WHO 2021c). It is rare to find a physician on the planet who has seen a case of smallpox at this point. There were two versions of smallpox: variola major, which caused a severe rash that led to disfigurement and killed 30% of those it infected, and variola minor, which was caused by a different strain and produced a milder form of the disease (Cruse and Lewis 2009). Two physicians who worked in the field in the 1970s have spoken publicly about their observations in a “Jenner Conversation” webinar recorded by the Jenner Museum during the COVID-19 pandemic. These physicians described their use of a smallpox recognition card to help identify any individuals in a household with smallpox during canvassing from home to home in an affected area (Figure 2.4) (Fine and Heymann 2020). They then used a “ring vaccination” approach to vaccinate individuals in a community, once they found either an individual who had smallpox or someone they had contacted (CDC 2021). As is the case with other public health issues, community-based efforts to tackle a disease are critical, and governments and institutions depend on these “on the ground” efforts for a successful vaccination campaign.
African Cities and Ebola
Published in Igor Vojnovic, Amber L. Pearson, Gershim Asiki, Geoffrey DeVerteuil, Adriana Allen, Handbook of Global Urban Health, 2019
Zacchaeus Anywaine, Ggayi Abubaker Mustapher
The Merck pharmaceutical vesicular stomatitis virus vectored Zaire ebolavirus vaccine (rVSV-ZEBOV) was found to be effective against EVD in Guinea during the West African epidemic (Henao-Restrepo et al. 2015). This was evaluated in a phase III open label cluster randomized trial using a novel ring vaccination approach employed in the eradication of smallpox in the 1970s (Fenner et al. 1988). Ring vaccination is defined as the vaccination of a cluster of individuals at high risk of infection, owing to their social or geographical connection to a confirmed case of disease. The ring vaccination strategy was used to vaccinate populations at risk of Ebola during an outbreak that occurred recently in the DRC four years after the West African epidemic (Figure 23.2).
Frequently Asked Questions
Published in Joseph R. Masci, Elizabeth Bass, Ebola, 2017
Joseph R. Masci, Elizabeth Bass
Ring vaccination is a containment strategy in which concentric rings of contacts of an infected person are traced, identified, and vaccinated. The initial ring typically may include family, neighbors, and coworkers. Then contacts of the inner ring are identified and vaccinated, and so on. It is a form of containment rather than primary prevention. This strategy was used successfully to eradicate smallpox in the 1970s, considered one of the most important successes of the twentieth century public health measures. It was also used in the trial of the rVSV–EBOV Ebola vaccine trial whose results were published in late 2016.
Ebola vaccine trials: progress in vaccine safety and immunogenicity
Published in Expert Review of Vaccines, 2019
Keesha M. Matz, Andrea Marzi, Heinz Feldmann
Vaccine strategies need to be developed targeting the different groups and scenarios as there is no single approach that fits all. Ring vaccination seems to be most potent when it comes to immediate intervention in acute outbreak situations, but one needs a fast-acting, prime-only vaccine approach such as VSV-EBOV. For medical and public health response personnel a prime-boost approach might be best to build up a durable vaccine response over time to have such personnel prepared for short-notice deployments. Here, the combined approaches with adenovirus prime and MVA boost may come into play. Strategies for running clinical trials should be in place and appropriate ethics approval should be prepared ahead of time to not delay response activities as happened during the West African epidemic. It remains questionable whether broader prophylactic use of vaccines in certain regions may be useful and justified as EBOV endemicity is not well defined. Furthermore, unknown durability, undefined mechanisms of protection and potential adverse effects of vaccine candidates may also not yet favor a wider prophylactic population-based vaccine usage. Here, multivalent vaccine approaches targeting more common pathogens in combination with EBOV might be a helpful solution to boost compliance.
Unprecedented pace and partnerships: the story of and lessons learned from one Ebola vaccine program
Published in Expert Review of Vaccines, 2018
Swati B. Gupta, Beth-Ann Coller, Mark Feinberg
The results from one Phase II/III cluster randomized ring vaccination trial found the vaccine to be highly efficacious and effective. To date, the vaccine has been given to over 17,000 people, and is believed to have an adequate risk/benefit profile as well as robust immunogenicity and is progressing towards licensure with the U.S. and European regulatory agencies.