Vaccines go through rigorous testing to ensure they are safe, especially before being used in mass vaccination programs. Their production and distribution are strictly controlled to ensure safety. All vaccines used in Turkey are licensed by the World Health Organization (WHO), the European Medicines Agency (EMA), the U.S. Food and Drug Administration (FDA) or the Turkish Medicines and Medical Devices Agency (TİTCK) of the Ministry of Health of the Republic of Turkey. All were produced in compliance with the Good Manufacturing Practices (GMP) approved by the WHO. All series of vaccines produced undergo detailed analyses and tests by both the producers and the official authorities of the country they have been produced in. Safety, efficacy analyses, and suitability tests of the purchased vaccines and antisera are conducted by experienced personnel using advanced technology at the Medicine, Biological and Medical Products Laboratory (MBMPL). The MBMPL is the national reference laboratory overseen by the Turkish Medicines and Medical Devices Agency. Vaccines and antisera are only cleared for administration by the authorities once they have passed testing and were proven safe. Vaccines failing to pass the analyses are returned to producers, and vaccines from other series are requested instead for testing.

Once received from the producer firm, vaccines are stored within recommended temperature ranges in the cold chain until administration. The Ministry monitors the properties of each vaccine dose continuously via the Vaccine Tracking System (VTS).   

Vaccines may contain multiple agents, chief of which are: antigens, adjuvants, stabilizers, and preservative substances. The antigen plays a key role in enabling the immune system to develop immunity whilst the remaining agents are responsible for easier production, safety, and vaccine efficacy. Porcine products are not used in the production of vaccines used by the Ministry of Health of the Republic of Turkey. 

Adjuvants are used together with the bacterial and viral parts of the vaccine to increase efficacy. A commonly used adjuvant is aluminium hydroxide. Stabilizers are substances added to vaccine vials to preserve the stability of the vaccine until administration. Magnesium chloride is a common stabilizer. Preservative substances prevent microbial contamination of vaccines during storage in vials. Common preservatives are thiomersal and antibiotics such as: neomycin, kanamycin, and erythromycin.

Aluminium hydroxide is an adjuvant that makes vaccines more effective even in very low doses. The total aluminium amount contained in the vaccines administered throughout the lifetime of an individual is 4.25 mg. This amount estimated by the WHO is too low to be harmful to individuals and exists in vaccines such as: Td, DTaP-IPV-Hib, DTaP-IPV, and the KPA vaccine. Aluminium is also abundantly present in drinking water, bottled water, flour, flour products, fruits, vegetables, and medications, particularly in antacid medications (20-30 mg). Thiomersal is an organic compound of ethyl mercury and has been in use as a preservative in a number of vaccines and medications since the 1930s.  

A June 2002 report by the WHO Global Advisory Committee on Vaccine Safety (GACVS) explains that the half-life of ethyl mercury (thiomersal) in the body is shorter than a week and that it is eliminated from the body through the digestive system in 4-9 days on average. Therefore, it does not accumulate in the body like other mercury compounds and does not cause any chronic diseases related to mercury. Methyl mercury, which is difficult to eliminate from the body, is different from thiomersal and is not included in vaccines. 

A number of scientific studies have been conducted to investigate the alleged relationship between thiomersal-containing vaccines and developmental disorders such as autism. None of these studies have found a relationship between thiomersal and autism. 

Following up on the detailed research by the WHO Global Advisory Committee on Vaccine Safety, the European Medicines Agency reported in a March 2004 study by its Committee for Proprietary Medicinal Products (CPMP) that there is no relationship between immunization with thiomersal-containing vaccines and specific neurological developmental disorders.

The Institute of Medicine (IOM) of the American Independent Civil National Academies of Science (NAS) concluded in its 2004 report that there was no link between autism and the measles vaccine or other vaccines containing thiomersal as a preservative. They found that the development of autism in patients receiving these vaccines was entirely coincidental, and the President of the Institute of Medicine (IOM) Harvey V. Fineberg, in his interview broadcast on NBC television on 7 August 2005, stated that there was no relationship between thiomersal and autism. European countries and many others, the use of thiomersal as a preservative in vaccines continues. The WHO Global Advisory Committee on Vaccine Safety also declared that the measles vaccine is not associated with SSPE and autism. A fraudulent article on the subject that got published in The Lancet magazine in 1998 was retracted in 2010 after severe scientific criticism and its lead author was banned from the medical profession. 

Various studies over many years have demonstrated no proven side effects from the use of thiomersal in vaccines. Moreover, thiomersal is usually found in multi-dose vaccines and is generally not found in single-dose vaccines.

SUBSTANCES FOUND IN VACCINES