Because tattoos and ear piercings are unsanitary. Now tattoo and ear piercing technology is very mature, ear piercing is no longer a patent for girls, and many boys wearing trendy clothes will try this experience. However, there are still hidden dangers such as incomplete disinfection of tools in some places. However, when they came to donate blood for free, they found that many diseases had a long window period. There is no guarantee that you won't get sick. But I was told that I couldn't donate blood within one year after I had my ears pierced.
Tattoos or pierced ears may be infected with bacteria. Because there is a window period problem in pathogen detection of blood-borne diseases, in addition, blood donation can only be made after one year of rabies vaccine injection and four weeks of measles vaccine injection. Therefore, for the sake of patients' health, tattoos and ear piercings are not allowed to donate blood within one year. The main reason is that drilling holes in places with cartilage tissue such as auricle and tragus is easy to cause infection of infectious pathogens. In severe cases, it will lead to cartilage necrosis, deformation and ear atrophy.
Many infectious diseases have a window period. For example, people who receive inactivated vaccines, recombinant DNA vaccines and toxoid injections, such as influenza virus inactivated vaccines, can use nationally recognized diagnostic reagents to detect pathogen markers for a while. Even induce facial paralysis. People vaccinated with live attenuated measles vaccine will prick their skin when they have their ears pierced. If the tools are unsanitary and they are vaccinated, many people will respond to protect blood donors and recipients.
Infected diseases after tattooing or ear piercing will not be revealed, because the infected diseases have a window period and can only be completely discovered in one year.