Which level of prevention does disease screening belong to?

The current general consensus in the public health field is that most disease screenings fall into the category of secondary prevention, and only a few special screening scenarios have classification disputes.

The core of secondary prevention is the three-early strategy of "early detection, early diagnosis, and early treatment." The routine screenings we usually come into contact with the most basically fit this positioning - such as free community cancer screening for women over 35 years old, low-dose chest CT scans for lung cancer and fecal occult blood tests for the elderly. The purpose of colorectal cancer screening is to screen out potential early-stage patients before the typical clinical symptoms of the disease appear, and to intervene as early as possible to interrupt the course of the disease. It is like doing a routine pressure test on the water pipes at home, fixing the leaks as soon as they are discovered, and then repairing them after the water pipe bursts and the furniture is soaked. It is expensive and troublesome.

However, many public health practitioners and scholars have different views on the classification of some special screenings, such as screening for pathogenic factors in high-risk groups, such as hepatitis C antibody screening for people with a history of intravenous drug use, and HIV screening for people who have had high-risk sexual behaviors. If the infection is screened and timely intervention is initiated, it can not only prevent the infected person from progressing to the disease stage, but also cut off the link of further transmission from the source. Many people believe that this kind of screening that points to the front end of the disease and cuts off the path of disease is closer to the positioning of primary prevention.

When I was stationed at a street public health station, I met a young man who took the initiative to undergo screening after engaging in high-risk behaviors. After he was found to be HIV-positive, he started intervention and treatment in a timely manner. His subsequent viral load has been controlled at an undetectable level. Not only is he basically the same as a healthy person, but he will not pass it on to his partner. The role of this kind of screening is actually not much different from the logic of vaccination to prevent infection.

In fact, the struggle to classify is more of an academic discussion. For us ordinary people, as long as it is a screening that is suitable for our age group and risk level, it is definitely better to do it regularly than not to do it at all. After all, if the prevention and control port is moved one step forward, the risk of disease can be greatly reduced.