Oral cholera vaccines and their impact on the global burden of disease

Abstract

With one-third of nations at risk of cholera, we can expect to experience massive, rapidly disseminated, and prolonged cholera outbreaks such as those recently experienced in Yemen and Haiti. The prevention of cholera outbreaks like these includes the provision of potable water, sanitation, and hygiene (WASH). This approach has been known for generations. However, it will be many years before universal global access to WASH is achieved. While working toward universal WASH, study data has shown that licensed and WHO prequalified cholera vaccines are important tools for cholera prevention. Oral inactivated whole-cell vaccines such as Shanchol and Euvichol-plus provide well-documented direct benefits to vaccine recipients and to the unimmunized through herd protection. Manufacturers have now increased the cholera vaccine supply, and since 2013 vaccine doses have been available for emergency and endemic control through a global stockpile. Advances in packaging and vaccine temperature control, reduced vaccine costs, the inclusion of pregnant women in vaccine campaigns, and a targeted approach to high incidence endemic areas are further increasing the usefulness of these vaccines for reducing the global cholera burden.

NTDs in the 2020s: An epic struggle of effective control tools versus the Anthropocene

“…A new Ebola virus vaccine is being used to combat a large epidemic in eastern DR Congo, with more than 200,000 people vaccinated to date and preliminary assessments suggesting it is highly effective [21]. Similarly, cholera vaccines have been stockpiled by WHO and have found use in multiple reactive settings where outbreaks are underway [22]. Many of the vaccines that prevent or treat NTDs are only partially protective so they may not necessarily replace existing control approaches, but rather they would likely be developed and implemented as companion technologies [23].…”

Combating Cholera

“…The objective of antibiotics to treat cholera infections is to reduce both (1) the time and severity of the illness and (2) the transmission to other individuals. Acute infection with severe dehydration is treated with ORT and antibiotics to produce synergistic efficacy 10– 12, 16 . Effective antibiotics to treat cholera are doxycycline, azithromycin, and tetracycline.…”

“…One widely used WC strain vaccine is Dukoral (CTB-WC), which contains inactivated/dead V. cholerae O1 (El Tor and classical biotypes) with the addition of recombinant B subunits of CT (CTB) 12, 16, 30, 31 . The effectiveness of Dukoral is between 55% and 88% 17 , and it is intended for travelers but—owing to its short period of usability, high cost, and its requirements for cold-chain circulation—not for populations in endemic regions 9, 25 .…”

“…The effectiveness of Dukoral is between 55% and 88% 17 , and it is intended for travelers but—owing to its short period of usability, high cost, and its requirements for cold-chain circulation—not for populations in endemic regions 9, 25 . Dukoral can provide protection from infection for 2 years in vaccinated individuals above the age of 5, but it is effective for only 6 months between the ages of 2 and 5 and requires at least two doses to be effective 16 . Unlike Dukoral, Shanchol and Euvichol are WC vaccines composed of inactivated O1 Inaba, O1 Ogawa, and O139 strains, but these vaccines do not contain CTB 16, 32 .…”

“…Virtually all modern-day cholera is caused by El Tor, and environmental sampling identifies only El Tor, suggesting that classical biotypes are no longer prevalent. The El Tor biotype can be grouped into the serotypes Ogawa and Inaba, which are the most prevalent serotypes that are causing the pandemics 2, 14, 15 , and these are used in contemporary vaccines like Shanchol and Euvichol 16 . Even with modern-day treatments, it is estimated that there are over 3 million cases of cholera with more than 100,000 deaths annually 16– 18 .…”