A new Harvard study suggests that a new diagnostic tool can detect every virus you have ever been exposed to. The new tool is a simple blood test that takes just a single drop of blood. From this single drop of blood, doctors can analyze and reveal every virus a person has had throughout the course of their life. A tool like this is groundbreaking for the medical community because currently, doctors are only able to test for specific viruses.

The problem with viruses is that once a virus has infected our body, we cannot see it until it makes us sick. Some people have a subclinical infection which is when you have been exposed to a virus but are not yet sick, or, you may never get sick at all. Regardless of whether you may never get sick from a virus, it is essential to know whether you have been exposed to one because viruses can lay dormant or hide within the body for many years. They can eventually lead to autoimmune diseases, cancer, and all kinds of health problems.

With this new blood test, doctors can look at the DNA and see all the possible viruses that a person has been exposed to. This would make it so that people do not have to wait until they become sick or start to see symptoms of a virus in which they were never aware they had.

The blood test is only in clinical research at the moment and is not yet ready for use in the doctor’s office. However, it has been looked at in countries around the world including South African, Asia, the United States, and in South America.

This new blood test is important because preventive medicine is key. By being able to predict what problems may lie ahead given any viruses you have been exposed to, doctors can prevent those problems. For example, if a woman has been exposed to HPV, the doctor will know to screen for cervical cancer. Or, if someone has been exposed to hepatitis C, the doctor will know to look out for liver cancer. The list goes on and on.

The new test that researchers have developed a DNA-based blood test called VirScan. VirScan works by screening the blood for antibodies against any of the 206 species of viruses known to infect humans. When a virus infects the body, the immune system produces certain antibodies to fight the virus. The immune system will also produce these antibodies for years after the initial infection to prevent the virus from harming the body. This is how a virus lays dormant in the body. However, if a virus is strong enough, it can awaken and cause serious health problems. VirScan detects those antibodies and uses them to identify nearly every virus a person has been exposed to. This is much different than the current method for diagnosing viruses, which can only be tested for one at a time.

VirScan can detect the 206 virus species known to infect humans and more than 1,000 known virus strains just by testing a small amount of blood. Researchers tested VirScan on almost 600 people and detected an average of 10 strains per person. At least two people tested positive for 84 strains.

This new blood test could be a game-changer for diagnostic and preventive medicine because it could help doctors trace how viruses spread. Researchers also say they believe the test could be expanded as new viruses are discovered.