SOME parents are bit hesitant when it comes to immunizations and thus some tend to either give their children all immunizations available or not bother with any. Melinda Henry, a vaccination specialist at the World Health Organization (WHO) told Arab News that, contrary to a widely held belief, there is currently no evidence of mercury toxicity in infants, children, or adults who are exposed to Thiomersal from vaccines. She adds that the benefits of vaccinations far outstrip any risks.
This is based on the ongoing safety review of available evidence and outcomes of epidemiological studies, the Global Advisory Committee (GAC) on Vaccine Safety, which acts as the scientific and clinical advisory body to WHO on vaccine safety issues.
The GAC on Vaccine Safety also said that there is no reason to change current immunization practices with Thiomersal-containing vaccines on the grounds of safety. The safety of Thiomersal-containing vaccines is reviewed at regular intervals.
“In the meantime, the available evidence warrants recommendation that current WHO immunization policy with respect to Thiomersal containing vaccines should not be changed,” she said.
Some national public health authorities, she said, are striving to replace Thiomersal-containing vaccines with Thiomersal-free vaccines as a precautionary measure. However, there are only a few alternatives to Thiomersal-containing vaccines. The current production capacity for such vaccines is limited and is insufficient to cover global needs.
The decision whether to license Thiomersal-containing, Thiomersal-free vaccines or both options is solely in the domain of national health authorities. Their decision may be based on the availability of sufficient doses of the specific vaccine product, safety profile of available products, target recipient group, immunization schedule, vaccine cost, and a variety of logistical issues that include cold chain capacity. The decisions may vary for different scenarios particularly with regard to response to a pandemic situation.
National public health authorities formulate vaccination schedules and base their decisions on the epidemiological situation, disease burden in specific age groups, ability to provide immunization through public health sector and available resources. This is why vaccination schedules differ between countries. Vaccination schedules are revised from time to time in order to improve protection of the population. Pending on the available resources, booster doses are provided later during childhood, through school-based immunization programs or to the adult population through special immunization programs.
From the public health perspective, a fully immunized infant should be vaccinated against polio, diphtheria, tetanus, pertussis, measles and tuberculosis. However, tuberculosis immunization is sometimes removed from vaccination schedules in the countries with low disease incidence. Many countries introduced hepatitis B, Haemophilus influenza type B, mumps and rubella vaccines to their schedules. Some provide immunization against specific diseases present in their region like yellow fever or Japanese encephalitis.
Vaccines are also available for protection against other diseases that may not be seen as a public health priority, but are given on an individual basis according to individual needs.