This strategy vaccinates the contacts of confirmed patients, and people who are in close contact with those contacts. This way, everyone who has been, or could have been, exposed to an infected person receives the vaccine, creating a 'ring' of protection that can limit the spread of disease. It requires thorough and rapid surveillance and epidemiologic case investigation.
The method was first used in Leicester, England in the late 19th-century. The Intensified Smallpox Eradication Program used this strategy with great success in its efforts to eradicate smallpox in the latter half of the 20th century. It was later used to contain ebola in the Western African Ebola virus epidemic.
Ring vaccination is used to stop the spread of a disease by vaccinating those around the infected person. It relies on contact tracing to determine possible infections. However, this can be difficult. In some cases, it is preferable to vaccinate as many people as possible within the geographic area of known infection (geographically-targeted reactive vaccination). If the infections occur within a defined geographic boundary, it may be preferable to vaccinate the entire community in which the illness has appeared, rather than explicitly tracing contacts.
Many vaccines take several weeks to induce immunity, and thus do not provide immediate protection. However, even if some of the ill person's contacts are already infected, ring vaccination can prevent the virus from being transmitted again, to the ill contacts' contacts.[medical citation needed] A few vaccines can protect even if they are given just after infection; ring vaccination is somewhat more effective for vaccines providing this post-exposure prophylaxis.
When responding to a possible outbreak, health officials should consider which is best, ring vaccination or mass vaccination. In some outbreaks, it might be better to only vaccinate those directly exposed; variable factors (such as demographics and the vaccine that is available) can make one method or the other safer, with fewer people experiencing side-effects when the same number are protected from the disease.
In 2018, health authorities used a ring vaccination strategy to try to suppress the 2018 Équateur province Ebola outbreak. This involved vaccinating only those most likely to be infected; direct contacts of infected individuals, and contacts of those contacts. The vaccine used was rVSV-ZEBOV.
Ring vaccination has been used extensively in the 2018 Kivu Ebola outbreak, with over 90,000 people vaccinated. In April 2019, the WHO published the preliminary results of the research by its research, in association with the DRC's Institut National pour la Recherche Biomedicale, into the effectiveness of the ring vaccination program, stating that the rVSV-ZEBOV-GP vaccine had been 97.5% effective at stopping Ebola transmission, relative to no vaccination.
- Cocooning (immunization)
- Herd immunity
- Pulse vaccination strategy
- Targeted immunization strategies
- Finn, Adam (2021). "2. How vaccinating people can also protect others". In Vesikari, Timo; Damme, Pierre Van (eds.). Pediatric Vaccines and Vaccinations: A European Textbook (Second ed.). Switzerland: Springer. pp. 15–20. ISBN 978-3-030-77172-0. Archived from the original on 2022-06-18. Retrieved 2022-06-17.
- "Ring Vaccination | Smallpox | CDC". www.cdc.gov. November 29, 2019. Archived from the original on May 8, 2022. Retrieved May 4, 2022.
- Edward A. Belongia and Allison L. Naleway, Smallpox Vaccine: The Good, the Bad, and the Ugly Archived 2022-05-01 at the Wayback Machine, Clin Med Res. 2003 Apr; 1(2): 87–92. doi:10.3121/cmr.1.2.87
- Walldorf, JA; Cloessner, EA; Hyde, TB; MacNeil, A; CDC Emergency Ebola Vaccine, Taskforce. (7 September 2017). "Considerations for use of Ebola vaccine during an emergency response". Vaccine. 37 (48): 7190–7200. doi:10.1016/j.vaccine.2017.08.058. PMC 5842136. PMID 28890191.
- "Understanding How Vaccines Work | CDC". www.cdc.gov. US Centers for Disease Control. 13 March 2019. Archived from the original on 2 January 2020. Retrieved 19 May 2019.
- Kretzschmar, Mirjam; Wallinga, Jacco; Teunis, Peter; Xing, Shuqin; Mikolajczyk, Rafael (2006-08-01). "Frequency of Adverse Events after Vaccination with Different Vaccinia Strains". PLOS Medicine. 3 (8): e272. doi:10.1371/journal.pmed.0030272. ISSN 1549-1277. PMC 1551910. PMID 16933957.
- Strassburg, M. A. (1982). "The global eradication of smallpox". American Journal of Infection Control. 10 (2): 53–9. doi:10.1016/0196-6553(82)90003-7. PMID 7044193.
- "World on the verge of an effective Ebola vaccine" (Press release). World Health Organization. Archived from the original on July 31, 2015. Retrieved 31 July 2015.
- James Gallagher (31 July 2015). "Ebola vaccine is 'potential game-changer'". BBC News Health. Archived from the original on 30 December 2019. Retrieved 30 July 2015.
- Henao-Restrepo, Ana Maria; et al. (31 July 2015). "Efficacy and effectiveness of an rVSV-vectored vaccine expressing Ebola surface glycoprotein: interim results from the Guinea ring vaccination cluster-randomised trial". The Lancet. 386 (9996): 857–866. doi:10.1016/S0140-6736(15)61117-5. hdl:10144/575218. PMID 26248676. S2CID 40830730.
- Aizenman, Nurith (May 15, 2018). "Can The New Ebola Vaccine Stop The Latest Outbreak?". NPR.org. Archived from the original on 2018-05-16. Retrieved 2018-05-16.
- Mole, Beth (2019-04-16). "As Ebola outbreak rages, vaccine is 97.5% effective, protecting over 90K people". Ars Technica. Archived from the original on 2021-02-19. Retrieved 2019-04-17.
- "Ebola Ring Vaccination Results 12 April 2019" (PDF). www.who.int. 12 April 2019. Archived from the original on 14 April 2019. Retrieved 17 April 2019.
- "First Ebola vaccine to be tested in affected communities one year into outbreak" (Press release). WHO. Archived from the original on 30 March 2015. Retrieved 5 May 2021.