What is a "viral load measurement" test?

This is an automatically translated article.

The article was professionally consulted with MSc Tran Thi Vuong - Doctor of Microbiology - Laboratory Department - Vinmec Hai Phong International General Hospital.
Viral load is the amount of virus present in the blood. This is a test used in the diagnosis of HIV infection and certain other viral diseases. According to the World Health Organization (WHO), approximately 1.5 million people died from HIV-related complications in 2013.

1. Virus load

Viral load is the amount of viral genetic material per unit volume of blood, usually in milliliters. Viral load helps doctors assess a patient's current viral infection status, monitor viral infection status, and assess the effectiveness of antiretroviral therapy.
This is a test that requires quite high technical expertise and meticulousness of the tester. Viral load is often indicated in chronic viral infections, blood-borne viral diseases such as hepatitis B, hepatitis C and HIV. Viral load in the same patient varies over time. Therefore, this test is often recommended to be done repeatedly to monitor the body's response to the viral agent. An increase in viral load means that the virus is multiplying strongly in the body and conversely a decrease in viral load means that the virus is being suppressed, either naturally or under the influence of antiviral drugs.
In essence, the viral load test is a quantitative PCR (polymerase chain reaction). In quantitative PCR, a term of great interest is virus detection threshold. Depending on the sensitivity of the reagent kit, the detection threshold may vary. Currently, there are many chemical kits with very low detection threshold, reaching 5 copies/ml of blood.

2. When should a viral load test be done?

Usually viral load testing is done at 2 points:
First, when infection is detected or when treatment is started. For example, when you go to a general health check-up, accidentally the blood test results show that you are infected with hepatitis B or C virus. When you want to assess how the virus is, the doctor will often advise doing more tests. viral load -> from here the doctor can also start prescribing antiretroviral therapy.
Second, testing is done during treatment, for the purpose of monitoring treatment, usually after 3-6 months of treatment or simply to monitor the progression of chronic disease (such as hepatitis B cases do not need treatment). If the viral load is reduced, it means the body responds to the treatment, you will have a good prognosis, the disease will progress well and vice versa, if the viral load does not decrease or decrease insignificantly, it will respond to the treatment. If the drug is poorly treated, it is possible that the virus has become resistant to the treatment drug and the doctor will advise changing the treatment regimen.
In general, patients with chronic hepatitis B and C virus infections and HIV-infected patients should be tested for viral load at least every 6 months.

3. What is an undetectable viral load?

Antiviral drugs are aimed at inhibiting viral replication by different mechanisms alone or in combination with different mechanisms in the same patient. With chronic infections such as chronic hepatitis B, C, HIV, antiretroviral therapy to reduce the load below the detection threshold is the success of the treatment course. An undetectable viral load means that the amount of virus in the blood is no longer present (eg, hepatitis C is completely cured) or is at least below the detection threshold of the PCR machine (as in patients with HBV, HIV). . Thus, the amount of virus in the patient's blood is very low, the risk of infecting others will also be greatly reduced, and more importantly, reducing unwanted complications caused by B, C, and HIV viruses: for example, reduce the possibility of cirrhosis, liver cancer with hepatitis B and C virus infection. Or with HIV-infected patients, when the viral load is below the detection threshold, the patient does not suffer from opportunistic infections, cell hyperplasia. CD4 cells, patient's life is greatly improved
Thus, viral load test is a common test and has high value in chronic infections such as hepatitis B, C and HIV.
Vinmec International General Hospital is one of the hospitals that not only ensures professional quality with a team of leading doctors, modern equipment and technology, but also stands out for its examination and consulting services. and comprehensive, professional medical treatment; civilized, polite, safe and sterile medical examination and treatment space. Customers when choosing to perform tests here can be completely assured of the accuracy of test results.

Please dial HOTLINE for more information or register for an appointment HERE. Download MyVinmec app to make appointments faster and to manage your bookings easily.