Bloodborne Viruses

Primary reference(s)

WHO, 2023. Blood safety and availability. World Health Organization (WHO). Accessed 1 April 2025.

Annotations

Key relevant UN convention / multilateral treaty

International Health Regulations (2005), 3rd ed. (WHO, 2016).

Drivers

Blood-borne viruses (BBVs) are transmitted by blood, or other body fluids containing the virus. This happens when the blood or fluids enter the body of a susceptible person. The rate of viral transmission varies depending on how the person has been exposed to the virus (the route of transmission), the type of virus, how much of the virus the carrier has in their body and the immune status of the exposed person (HSE, no date b).

The more common routes of transmission include sexual intercourse (common for HBV, HIV; inefficient for HCV); sharing injecting equipment; skin puncture by blood-contaminated sharp objects (e.g needles, instruments or glass); and childbirth (ie the mother infects the child either before or during birth, or through breast-feeding) (HSE, no date b).

Less common routes of transmission are: contamination of open wounds (e.g blood injuries during sporting activities); contamination of skin lesions (e.g eczema); splashing of the mucous membranes of the eye, nose or mouth; and human bites when blood is drawn (this may be more of a problem in certain occupations, e.g prison and police service, where front line workers may be exposed to violent behaviour) (HSE, no date b).

There is also a risk of acquiring a blood-borne virus infection via blood transfusion. For example, in the UK, all blood donations are screened for HBV, HCV and HIV, meaning the risk is remote (HSE, no date b). 

Health care workers are at risk of infection with blood-borne pathogens because of occupational exposure to blood and body fluids. Most exposures are caused by 'sharps' - contaminated sharp objects, such as syringe needles, scalpels and broken glass. Needlestick injuries contribute to 39%, 37% and 4.4% of hepatitis C, hepatitis B and HIV infections respectively (Prüss-Üstün et al., 2005).

Impacts

Bloodborne pathogens include the human immunodeficiency virus (HIV), hepatitis B virus (HBV), and hepatitis C virus (HCV) (CDC, 2024). These infections are, for the most part, preventable, as shown by the low rates achieved in certain countries that have engaged in serious prevention efforts, including training of health care workers, HBV immunisation, post-exposure prophylaxis and improved waste management. In addition to the disease, the burden caused to health care workers, and the functioning of the health care system may be reduced because of impaired working capacity, especially in developing countries where the proportion of health care workers in the population is already small compared with that in developed countries (WHO, 2005). 

Multi-hazard context

The figure below summarises common interactions between bloodborne viruses and other hazards. This information should be used with caution and not be solely relied upon in Disaster Risk Management, particularly as some interactions may not have been included. Note that hazardous events occurring together or locally in space or time may not necessarily cause, amplify or be otherwise related to each other. Specific examples of multi-hazard context can be found in the ‘Hazard drivers’ and ‘Impacts’ sections above.

Risk Management

Bloodborne virus transmission has been reported from patient to patient, patient to health care workers, and rarely, from health care worker to patient (Hu et al., 1991). For health care and other emergency workers, standard precautions are meant to reduce the risk of transmission of blood-borne and other pathogens from both recognised and unrecognised sources (WHO, 2007).  

Standard precautions are the basic level of infection control precautions which are to be used, as a minimum, in the care of all patients. Hand hygiene is a major component of standard precautions and one of the most effective methods to prevent transmission of pathogens associated with health care. In addition to hand hygiene, the use of personal protective equipment should be guided by risk assessment and the extent of contact anticipated with blood and body fluids, or pathogens (WHO, 2007).  

In addition to practices carried out by health workers when providing care, all individuals (including patients and visitors) should comply with infection control practices in health-care settings. The control of spread of pathogens from the source is key to avoiding transmission. Among source control measures, respiratory hygiene/cough etiquette is now considered as part of standard precautions, which include sterilization and medical device decontamination, safe handling of linen and laundry, use of personal protective clothing and management of health care waste (WHO, 2007; 2019).  

Worldwide escalation of the use of standard precautions would reduce unnecessary risks associated with health care. Promotion of an institutional safety climate helps to improve conformity with recommended measures and thus subsequent risk reduction. Provision of adequate staff and supplies, together with leadership and education of health workers, patients, and visitors, is critical for an enhanced safety climate in health-care settings (WHO, 2007). 

Of the 118.5 million blood donations collected globally, 40% of these are collected in high-income countries, home to 16% of the world’s population. In low-income countries, up to 54 % of blood transfusions are given to children under 5 years of age, whereas in high-income countries, the most frequently transfused patient group is over 60 years of age, accounting for up to 76% of all transfusions (WHO, 2023). 

The risk of transmission of serious infections, including HIV and hepatitis, through unsafe blood and chronic blood shortages brought global attention to the importance of blood safety and availability (WHO, 2023). With the goal of ensuring universal access to safe blood and blood products, WHO has been at the forefront of improving blood safety and availability, and recommends the following integrated strategy for blood safety and availability: 

• Establishment of a national blood system with well-organized and coordinated blood transfusion services, effective evidence-based and ethical national blood policies, and legislation and regulation, that can provide sufficient and timely supplies of safe blood and blood products to meet the transfusion needs of all patients.
• Collection of blood, plasma and other blood components from low-risk, regular, voluntary unpaid donors through the strengthening of donation systems, and effective donor management, including care and counselling.
• Quality-assured screening of all donated blood for transfusion-transmissible infections, including HIV, hepatitis B, hepatitis C and syphilis, confirmatory testing of the results of all donors screen-reactive for infection markers, blood grouping and compatibility testing, and systems for processing blood into blood products (blood components for transfusion and plasma derived-medicinal products), as appropriate, to meet health care needs.
• Rational use of blood and blood products to reduce unnecessary transfusions and minimize the risks associated with transfusion, the use of alternatives to transfusion where possible, and safe and good clinical transfusion practices, including patient blood management.
• Stepwise implementation of effective quality systems, including quality management, standards, good manufacturing practices, documentation, training of all staff, and quality assessment (WHO, 2023).  

WHO supports countries in developing national blood systems to ensure timely access to safe and sufficient supplies of blood and blood products and good transfusion practices to meet patient needs. WHO provides policy guidance and technical assistance to countries to ensure universal access to safe blood and blood products, and work towards self-sufficiency in safe blood and blood products based on voluntary unpaid blood donation to achieve universal health coverage (WHO, 2023).

Monitoring

WHO recommends that all blood donations should be screened for infections prior to use. Screening for HIV, hepatitis B, hepatitis C, and syphilis should be mandatory. Blood screening should be performed according to quality system requirements. Of reporting countries, 10 are not able to screen all donated blood for one or more of the above infections (WHO, 2023). 99.8% of the donations in high-income countries and 99.9% in upper-middle-income countries are screened following basic quality procedures, as compared to 83% in lower-middle-income countries and 76 % in low-income countries. The prevalence of transfusion-transmissible infections in blood donations in high-income countries is considerably lower than in low- and middle-income countries (WHO, 2023).