The National Agency for Food, Drug Administration and Control (NAFDAC) has said there are no unsafe vaccines approved for use in the country.
The agency also dismissed as false, reports that children in Nigeria were being administered a vaccine that contains 40 per cent mercury.
It stressed that stringent safe routine protocol are always followed before any human vaccines are administered.
In statement issued by the Director General NAFDAC, Prof. Mojisola Adeyeye on the alleged presence of mercury in vaccines in Nigeria, the agency said the only mercury component – thimerosal – used as vaccine preservative, was used in concentrations of 0.003 per cent to 0.01per cent.
“NAFDAC follows WHO approved protocol before issuing out lot release certificates before any human vaccines can be used in Nigeria, which is done after laboratory analysis and summary lot protocol review,” she said.
While assuring that NAFDAC was safeguarding the health of the nation, Adeyeye said there was lack of evidence that thimerosal presents risk to human health.
Adeyeye said: “It has come to our knowledge that a statement was made that children in Nigeria were being administered a vaccine that contains 40 per cent mercury which was prescribed by foreign organisation. This statement is not true Mercury is a metal, and it is not used as an element or as a component of vaccines.”
According to NAFDAC DG, World Health Organisation (WHO) has closely monitored the scientific evidence relating to the use thimerosal as a vaccine preservative for over 10 years especially through independent expert advisory group, the Global Advisory Committee on vaccines and confirmed its safe use.
Adeyeye explained that the basic components of vaccines are Antigens, adjuvants to improve immune response, antibiotics to prevent contamination during manufacturing, preservatives and stabilisers.
She said Thimerosal, a mercuric compound which is a preservative used in multi-dose vaccines contains a different form of mercury called ethyl mercury.
Explaining further, Adeyeye said thimerosal is a mercury-based preservative that has been used for decades in the United States in multi-dose vials (vials containing more than one dose) of medicines and vaccines.
She said WHO has not proscribed the use of thimerosal as an inactivating agent and preservative in vaccines as there is lack of evidence that thimerosal present risk to human health.
“There is no evidence of harm caused by the low doses of thimerosal in vaccines, except for minor reactions like redness and swelling at the injection site.
“However, in July 1999, the Public Health Service agencies, the American Academy of Paediatrics, and vaccine manufacturers agreed that thimerosal should be reduced or eliminated in vaccines as a precautionary measure.
“Nigeria still receives some multi dose vaccines which contains thimerosal but at accepted concentration,” she said.
Onyebuchi Ezigbo in Abuja