Cholera vaccination is the use of vaccines to protect and also treat people from the cholera diseases.  These vaccines are very effective in the prevention of cholera among disease, which is one of the most common communicable diseases in Nigeria, and Africa at large.

During the first six months after cholera vaccination, theses vaccines provide up to 85% protection from the cholera diseases, which helps to reduce an acute 50% - 60% during the first year; then after a two year continuous intake, the vaccines helps to decrease the diseases by over 50%. The moment the large populations of a cholera endemic area get vaccinated or immunized using these vaccines, it is likely to help protect others who are yet to get immunized from getting cholera (herd immunity).

The World Health Organisation (WHO) recommends the use of cholera vaccines in combination with other measures among those at high risk. The oral vaccines are the most common form of vaccine available in protecting people against cholera.

With the oral vaccines, two or three doses are typically recommended, and the duration of protection is two years in adults and 6 months in children aged 2 – 5 years. A single dose of this vaccine is available for those who might be traveling to endemic areas where cholera is common. However, since it does not provide 100% immunity from the disease, food hygiene precautions are also recommended when visiting area where there is a high risk of becoming infected with cholera. Although the protection observed has been described as “moderate”, herd immunity (as explained above) can multiply the effectiveness of these vaccines.

Currently, there are three types of qualified oral vaccines recommended by the World Health Organisation (WHO) namely Dukoral, Shancol, and Euvichol. All these three vaccines require two doses for full protection. Dukoral is administered with a buffer solution that, for adults, requires 150ml of clean water. Dukoral has been licensed for children two years and above.

In administering Dukoral, there must be a minimum of 7 days, and no more than 6 weeks, delay between each dose. Children between the ages of 2 – 5 require a third dose for full protection. And a full two doses of Dukoral would protect an adult for 2 years against cholera.

Shancol and Euvichol are essentially the same vaccine produced by two different manufacturers. They do not require a buffer solution for administration. They are given to all individuals over the age of one year. There must be a minimum of two weeks delay between each dose of these vaccines. Two doses of Shancol and Euvichol provide protection against cholera for 3 years, while a single dose provides short term protection.

Shancol and Euvichol are the vaccines currently available for mass vaccination campaigns all over the world i.e. through the Global OCV Stockpile which is supported by Gavi, the Vaccine Alliance and the World Health Organisation. Over 25 million doses of these OCVs have been used in mass vaccination campaigns. The campaigns have been implemented in areas experiencing an outbreak, in areas at heightened vulnerability during crisis, and among endemic areas e.g. Borno, Adamawa, Zamfara and Gombe states in Nigeria.

Presently, a mix of live, killed and conjugated vaccines are in development at the moment; that can potentially protect people from cholera for a longer term and also easy to administer.

Rare used is the injected cholera vaccines, which are effective for people living where cholera is common. They offer some degree of protection for up to 2 years after a single shot and for 3 – 4 years with annual booster. They reduce the risk of death from cholera by 60% percent in the first year after vaccination.

It is of importance to note that all these forms of vaccines (oral or injections) are generally safe, although mild abdominal pain or diarrhea may occur in some people due to body differences and reactions. They are safe in pregnant women and those with weak immune system.

CHOLERA VACCINATION IN NIGERIA

As discussed in our previous article on cholera epidemiology in Nigeria, we highlighted how cholera is quite endemic in the Northern region of the country, especially in the North – East and North West Region of the country.

North Eastern Nigeria (Bauchi and Adamawa)

From the year 2018 till date, the International Coordinating Group (ICG) has approved the release of over 1 Million doses of oral cholera vaccine (OCV) for a 2-dose emergency vaccination campaign in Adamawa and Bauchi States. The initial batch of 580, 605 doses of OCV was delivered to Nigeria on 22 June 2018 for the first round of the vaccination campaign while the second consignment of vaccines was released after successful implementation of the first round.

The vaccination campaign aimed at containing the current outbreak of cholera, which had affected more than 3000 persons including 104 deaths in both states.

The vaccination campaign has helped to stop the outbreak from spreading to more LGAs. This was why the State government with technical support of WHO requested ICG to release oral cholera vaccine for a 2-dose vaccination exercise.

Additionally, house-to-house teams including hard-to-reach teams and community health champions were already making a difference by alerting people on the risks and prevention of cholera, supporting early detection of cases and promoting household hygiene. Collectively, the teams sensitized more than 400,000 people on the dangers of cholera, how to prevent cholera infection and the importance of early reporting at the treatment center in the event of suspected diarrhea.

North – Western Nigeria (Zamfara, Katsina, Kebbi and Kano)

In 2018 (till date), due to the cholera outbreak in Zamfara, Katsina, Kebbi and Kano States in Nigeria, the World Health Organization (WHO) has supported health authorities in the North Western part of Nigeria with the necessary preparation for the implementation Oral Cholera Vaccination (OCV) campaigns.

With financial support from GAVI, the Vaccine Alliance, these vaccination campaigns directly protected 1,056,207 inhabitants of the four states who are aged one year and above from cholera.

The Country Office in Nigeria and the WHO Global Task Force on Cholera Control (GTFCC) has been actively supporting the Federal Government and States’ response since its outbreak in 2018. The interventions include a comprehensive risk assessment, which has led to ear-marking of 105 hotspot local government areas (LGAs).

And in addition to this initiative, WHO with the financial assistance from the UN’s Central Emergency Response Fund (CERF) provided immediate life-saving assistance to the individuals and communities affected by the outbreak and complement the Federal and States efforts.