Injections are a skin puncturing procedure performed with a syringe and needle to intro-duce a substance for prophylactic, curative, or recreational purposes. Injections can be given intravenously, intramuscularly, intradermally, or subcutaneously. Injections are among the most frequently used medical procedures, with an estimated 12 billion injections administered each year world-wide. A large majority (more than 90%) of these injections are administered for curative purposes (for every vaccina- tion injection, 20 curative injections are administered).

Injections have been used effectively for many years in preventive and curative healthcare. In preventive healthcare, injections have been used to administer vaccinations that have had a major impact in reducing childhood mortality due to measles and other vaccine-preventable diseases. While injections are still necessary today to administer most vaccina-tions, the number of vaccination injections could be reduced through the use of combination vaccines.

In curative healthcare, injections have been used to administer such antibiotics as penicillin, streptomycin as well as many other life-saving medications. Today, safe and effective alter-natives to injected medications are available and most medications used in primary care can be administered orally. Injections are predomi-nantly needed for the treatment of severe diseases, mostly in hospital settings. Never-theless, injections are overused to administer medications in many countries because of an ingrained preference for injections among healthcare workers and patients.

A safe injection does no harm to the recipient, does not expose the healthcare worker to any risk, and does not result in waste that is dangerous for the community. To achieve this, an injection needs to be prepared with clean hands in a clean area, using medication drawn from a sterile vial. The injection must be administered using a sterile syringe and needle. After administration, sharp equipment such as needles needs to be discarded in a puncture-proof container for appropriate disposal. When these rules are not followed, injections are unsafe and may expose recipients, healthcare workers, or the community to infections. Among unsafe practices, syringe or needle re-use between patients without sterilization is associated with a high risk of bloodborne pathogen transmission (see below). Unsafe injections occur in many parts of the world, and more particularly in developing countries where up to 50% of injections are administered with re-used syringes and needles.

The transmission of bloodborne pathogens through unsafe injections was documented as early as 1917, when an outbreak of malaria among British soldiers was linked to injection treatment for syphilis. Since then, unsafe injection practices have been linked to the transmission of many pathogens between patients (cross infection), including the hepatitis viruses, HIV, Ebola virus, dengue fever virus, and the malaria parasite. In addition, unsafe injections may cause abscesses, septicemia, or increase the risk of paralysis when patients are infected with the polio virus. Of all the adverse effects of unsafe injections, the hepatitis B and hepatitis C viruses, which are transmitted respectively a hundred times and ten times more effectively through unsafe injections than HIV/AIDS, cause the heaviest burden of disease.

When breaks in safe injection practices occur, overuse of injections increases opportuni-ties for bloodborne pathogen transmission. Reasons for popular demand for injections include beliefs that injections are stronger medications (Pakistan), that injections work faster (Romania), that the pain of the injection is a marker of efficacy (some African countries), that a drug is more efficient when entering the body directly (Colombia, Thailand), and that injections represent a more advanced techno-logy (many developing countries). Among healthcare workers, motivations for overuse of injections include belief of a better efficacy of injected drugs (Romania), ability to directly observe therapy, and thus compliance with treatment regimens, and, sometimes, financial incentives. In some healthcare systems (e.g., Pakistan), healthcare providers can charge a higher fee if they administer an injection.

Reasons that explain unsafe injection practices include lack of awareness regarding the risks associated with unsafe injections, lack of injection supplies, and lack of disposal infrastructure for injection equipment. Injection technology has developed considerably since its beginnings in the eighteenth century, moving from glass syringes that require sterilization after each use to plastic disposable syringes designed to be discarded after one single use. More recently, auto-disable disposable syringes modified to disable themselves automatically by the plunger blocking after one single use have been developed. Nevertheless, many countries cannot afford these more advanced techno-logies, which may cost twice as much as standard injection equipment. In some countries, such as India, syringes are scavenged for resale. On other continents, such as Africa, syringes and needles are reused until they break, as culturally, waste is not acceptable. For health budgets with limited resources purchasing policies can only address the most immediate concerns and thus cannot ensure safe equipment and increased supplies.

In many countries where hepatitis B and hepatitis C are highly endemic, unsafe injection practices account for a large proportion of infections. The proportion of new cases of hepatitis B that are attributable to unsafe injections was 60% in Taiwan in 1977 and 52% in Moldova in 1994. In Egypt, the proportion of new cases of hepatitis C that are attributable to unsafe injections exceeded 40% in 1996. The burden of disease associated with hepatitis B virus (HBV) and hepatitis C virus (HCV) has been likened to a ‘silent epidemic’, as these diseases typically take twenty years to evolve from infection to symptomatic chronic liver disease (cirrhosis and liver cancer).

Depending on the age at which infection occurs, 10% to 70% of persons infected with HBV develop a chronic infection. The younger the age at which infection occurs, the higher the risk of chronic disease. Of the 370 million people chronically infected with hepatitis B virus world-wide, more than one million die each year because of their infection; overall, 25% will eventually die of chronic liver disease. Hepatitis B is the fifth leading cause of death from infectious diseases in the world.

The proportion of individuals contracting HCV who develop chronic infection is even higher than for HBV. With 170 million people infected with HCV throughout the world, the burden of chronic liver disease and death associated with HCV infection is increasingly recognized, although no estimate is yet available.

Taken together, hepatitis B and C account for 75% of all cases of chronic liver disease world-wide and, while no estimate is available for the whole world, the annual cost of hepatitis B and hepatitis C in the United States alone has been estimated at $ 1.3 billion (medical and work loss). As the diseases progress and symtpoms become more acute, loss of health incurs absence from work, inability to support family, and loss of social position. Every carrier of the disease, whether symptomatic or asymptomatic, is a potential sourceof infection to others.

In addition to hepatitis B and hepatitis C, unsafe injections may cause HIV infection. However, because HIV is less efficiently transmitted through injections than the hepatitis viruses, unsafe injections account for far less infections than unprotected sexual intercourse in countries where HIV infection is highly endemic.

To prevent the transmission of bloodborne pathogens that results from unsafe injections, injection use must be reduced and injection safety must be achieved. To move populations away from injection overuse and toward oral medications, behavioral change of patients and healthcare workers should be encouraged through the combination of a supportive environment and Information, Education, and Communication (IEC) activities. Health infrastructures must be adapted and the issue of negative incentive (e.g., higher fee for services when an injection is prescribed) must be addressed, bearing in mind that oral treatment is less labor-intensive (requiring less health workers) and often more cost-effective (cheaper drugs, less staff involved). In addition, to achieve injection safety, a combined strategy to improve awareness and healthcare worker performance, provide injection supplies, and strengthen disposal infrastructure must be developed. The medical device industry should also be encouraged to develop safer technology that is adapted to national public health requirements and government budget capabilities.

To prevent the adverse effects of unsafe injection practices, United Nations organiza-tions, non-governmental organizations, govern-ments, donors, and universities sharing a common interest in a safe and appropriate use of injections joined their forces in a Safe Injection Global Network (SIGN). Because of the complexity of the problem, assistance from different types of professionals will be needed (e.g. public health officers, infection control practitioners, epidemiologists, anthropologists, specialists in behavior development, researchers in administration technology, environmen-talists). Because little experience is available regarding integrated programs that link the community with the health system to aim at safe and appropriate use of injections, the Safe Injection Global Network plans to co-ordinate the launch of pilot projects in five countries. Results of the evaluation of these pilot projects should be available by 2002, and will enable the Safe Injection Global Network to identify strategies that work to develop a large-scale initiative to ensure that safe and appropriate use of injections is a priority for all.