The suspected serial poisoning at a hospital in Yokohama, in which two elderly patients died over just a few days in late September after they received intravenous drips allegedly laced with disinfectant, highlights the need to beef up security at medical and welfare facilities — which, according to people familiar with the situation, are generally vulnerable to deliberate acts to harm people, including patients.

Security systems in hospitals and care facilities are often said to be based on a positive view of human nature — that people, including staff and visitors, are not out to commit malicious acts against others. Hospital safety measures focus instead on prevention of medical accidents and errors. But in reality, many incidents have taken place where vulnerable patients have been exposed to harm — and in some cases lost their lives — in these supposedly safe places. There may be limits to how much security can be brought to bear at these institutions, including staffing levels. But that can't be an excuse for not doing what can be done.

Many of the inpatients at Oguchi Hospital in Yokohama are reportedly in the terminal stage of their illnesses, with most either bedridden or having trouble walking on their own. The two male victims — both 88 years old — were among such patients, treated in the same eight-bed room on the institution's fourth floor. One of them died in the early morning of Sept. 20, just hours after he was administered an IV drip. A chemical contained in a disinfectant stored at the nurses station on the floor — which is used to disinfect surgical instruments — was found in his body as well as in his IV drip bag. A subsequent autopsy of the other victim, whose death three days earlier was initially diagnosed as due to his illness, found the same chemical component in his body. It is suspected that somebody injected the chemical by piercing small holes in the rubber plug that connects the IV bag and tube.