Ring vaccination

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Ring vaccination
A vaccination

Ring vaccination is a strategy to inhibit the spread of a disease by

vaccinating those who are most likely to be infected.[1]

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 a patient receives the vaccine, creating a 'ring' of protection that can limit the spread of a pathogen.

Ring vaccination requires thorough and rapid surveillance and epidemiologic case investigation. 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.[2]

Medical use

Ring vaccination was part of this response to a diphtheria epidemic, Berlin, 1962

When someone falls ill, people they might have infected should be

vaccinated. Contacts who might have been infected typically include family, neighbours, and friends. Several layers of contacts may be vaccinated (the contacts, the contacts' contacts, the contact's contacts' contacts, etc.).[3]

Ring vaccination 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.[4]

Many vaccines take several weeks to induce immunity, and thus do not provide immediate protection.[5] 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.[4]

Advantages

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.[6]

History

Ring vaccination was used in Leicester, England in the late 19th-century.[7] It was also used in the mid-20th century in the eradication of smallpox.[8][9]

It was used experimentally in the

Ebola virus epidemic in West Africa.[10][11]

In 2018, health authorities used a ring vaccination strategy to try to suppress the

rVSV-ZEBOV.[12]

Ring vaccination has been used extensively in the

rVSV-ZEBOV-GP vaccine had been 97.5% effective at stopping Ebola transmission, relative to no vaccination.[13][14]

See also

References

  1. PMID 26691346
    .
  2. ^ "Ring Vaccination | Smallpox | CDC". www.cdc.gov. November 29, 2019.
  3. ^ "Ring Vaccination: Smallpox | CDC". www.cdc.gov. US Centers for Disease Control. 15 February 2019. Retrieved 19 May 2019.
  4. ^
    PMID 28890191
    .
  5. ^ "Understanding How Vaccines Work | CDC". www.cdc.gov. US Centers for Disease Control. 13 March 2019. Retrieved 19 May 2019.
  6. PMID 16933957
    .
  7. doi:10.3121/cmr.1.2.87
  8. PMID 7044193
    .
  9. ^ "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.
  10. ^ James Gallagher (31 July 2015). "Ebola vaccine is 'potential game-changer'". BBC News Health. Retrieved 30 July 2015.
  11. S2CID 40830730
    .
  12. ^ Aizenman, Nurith (May 15, 2018). "Can The New Ebola Vaccine Stop The Latest Outbreak?". NPR.org. Retrieved 2018-05-16.
  13. ^ Mole, Beth (2019-04-16). "As Ebola outbreak rages, vaccine is 97.5% effective, protecting over 90K people". Ars Technica. Retrieved 2019-04-17.
  14. ^ "Ebola Ring Vaccination Results 12 April 2019" (PDF). www.who.int. 12 April 2019. Retrieved 17 April 2019.

Further reading

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