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Haiti - Epidemic : Vaccination against cholera, true or false hopes ?
WHO had declared earlier this year "In countries where cholera is endemic, vaccination of the general population is not justified, should be better targeted vaccination on areas and population groups at high risk (preschool and school, pregnant women people with HIV positive) and would imply periodic vaccination campaigns".
A group of experts convened by PAH /WHO at a meeting in Washington DC, has recommended the use of current vaccines for a pilot project in Haiti that would be extended progressively to the availability of vaccines. Currently, there are only 200.000 to 300.000 doses of vaccine against cholera, available worldwide said Dr. Ciro de Quadros, executive vice president of the Sabin Vaccine Institute. PAHO reported that it had recently located reserves to make more than a million doses of Shanchol. But it will take several months before the vaccine is ready, said Dr. Quadros. Shared information indicates that one million doses may actually be available by late 2011.
Until recently, oral vaccines against cholera, easier administrable, have been little used. immunization generally requires two doses per adult and 3 per child spaced at least one week. A recurring reminder is necessary which the frequency varies with age of the patient. The vaccine provides protection a week later. The effectiveness of this protection appears to be variable, but people who are vaccinated and would be again contaminated, they would escape to the severe form of the disease.
Physicians who attended the meeting recommended to contact the manufacturers to see if they can increase production and work with groups that can help finance the purchase of these vaccines.
There are 3 brands of vaccine against cholera in the world: Dukoral ($40 per dose) is manufactured in Sweden and approved by the WHO, Shanchol ($6 per dose) is produced by Shantha Biotechnics in India and the Morc VAX-VaBiotech is produced in Vietnam. Dukoral is approved by WHO, while for two other vaccines, only Shanchol is awaiting for a pre-qualification by WHO (this could be done in the first or second quarter of 2011). The Shanchol, was created by the International Vaccine Institute in Seoul (South Korea), through a grant from the Bill & Melinda Gates Foundation. Strain existing in Haiti, providing genetic similarities with the strain found in India, Nepal, Bangladesh and Pakistan where the epidemic kills each year over 100,000 people according to estimates of health professionals .
Dr. Jon K. Andrus, assistant director of the Pan American Health Organization (PAHO), explains that in general, 75% of people infected with cholera do not show symptoms but can still spread the disease to other people for a maximum period of two weeks after infection. A particularly high risk in areas where good hygiene is lacking, as in many regions of Haiti and especially in the refugee camps. "From the time where the cholera was firmly established in Haiti, it is clear to us, it will not disappear for several years. "
There is no example in the world, of mass vaccination for cholera during an epidemic. This lack of experience and considerable logistical problems related to the preparation, storage of vaccine and monitoring of patients (phase vaccination and reminders) make the application of a large-scale vaccination complex and difficult. For example, The Dukoral must be mixed with effervescent granules provided and dissolved in water and must be stored between +2° C to +8° C and should not be frozen. Once the effervescent granules dissolved in water and the vaccine in suspension added, the mixture should be drunk within two hours. It is necessary to add to the problems of vaccination, the detection of cholera carriers without symptoms and the difficulties of access to reach remote populations in the absence of roads...
Time is against the Haitian people. Since the beginning of the epidemic of cholera in the country on October 19, 2010, nearly 10% of the Haitian population could have been affected by cholera. The last official assessment of the Ministry of Health and Population (MSPP) dated of December 17, report that 121.518 people were infected whose 63.711 people were hospitalized for treatment.
If we consider that the health experts of the UN estimate that the Haitian government figures, largely under-estimated, could be double those published, we thus reach 243.036 people infected show symptoms of the disease (25% of people) over 972.144 people affected by the disease (approximately 10% of the population of Haiti) or 8 times to government figures. Moreover, Dr. Martin Weber, an expert on tropical diseases, said last week that "published figures are completely undervalued. I think we can easily multiply by ten the number of victims of the epidemic" this is pretty close to our estimates.
Although if the vaccination of 50% of the population would be enough to stop the epidemic (and not to eradicate cholera), it is clear that the vaccination of more than 4 million Haitians is not currently realizable within a foreseeable period. The vaccine is probably not the miracle solution, but it would allow save lives and especially to gain time to put in place across the country, measures of sanitation, the only able to eradicate this disease.