One of the principles of public health is simplicity. But in reality, the anti-epidemic policy in Vietnam is very difficult to understand for the people. The story ‘green card’, ‘yellow card’ is an example that goes against science.
As I find out  and a simple description for easy tracking, a green card is for someone who has had 2 full doses of vaccines (AstraZeneca, Pfizer, Moderna, Sinopharm, Sputnik), while a yellow card is for someone who has consumed 1 dose.
If so, why should it be called a green card or a yellow card to cause an extra layer of complexity. Why not call it 2 doses and 1 dose for easy understanding.
Here in Australia, people don’t have green cards, yellow cards; there is only one electronic certificate that has given 2 doses of vaccine. And, as far as I know in the UK, USA, Canada, there are no green cards or yellow cards; they only have one Australian certificate but the name is a bit different (like ‘Covid Pass’, ‘Vaccination Card’). Therefore, green card, yellow card is an ‘initiative’ only in Vietnam, but is not necessary.
It is not necessary to have standards for testing after vaccination. In fact, the green card regulation also adds a standard that is ‘routine antigen testingì‘. But the question is Why do you need an antigen test after vaccination??
In the past there have been cases of people who received vaccines and then went for PCR and/or antigen tests and got positive results. Interpretation of this result is rather delicate. In theory, vaccination cannot give a positive result. Most likely a positive result is a sign that the person was infected before or after the vaccination.
The question is, do people who have been vaccinated need to have an antibody test? Many people suspect that after vaccination, it is not certain that it is effective, so they ask for an antibody test. But maybe this is not the right thing to do. The reason is that these tests tell us a person has been exposed to the virus in the past, they are not a reliable measure of immunity against the virus.
Why is an antibody test not a reliable measure? Because these tests only tell us whether anti-nCov antibodies are present or not present, but we do not quantify, do not tell how much antibodies are in the body. This means that a person may test positive, but the amount of antibodies may not be enough to protect against the virus. On the other hand, if the test result is negative, it does not mean that the person is not immune, because other components of the immune system (such as T cells) can play an important role in the immune system. anti-virus.
For these reasons, health officials do not recommend testing people who have been vaccinated .
In short, I find it unnecessary to issue color tags. It is not necessary to require a covid test for those who have had the full dose of the vaccine. All it takes is a certificate that they have received 1 or 2 doses of the vaccine. Don’t make up a story to complicate a very simple matter.
 Actually, the condition is a bit more complicated than what I summarize. As far as I know from research, it is as follows:
- For 2-dose vaccines (AstraZeneca, Pfizer, Moderna, Sinopharm, Sputnik V): 14 days after the 2nd dose and routine antigen testing for some work environments.
- People infected with SARS-CoV-2 have recovered from the disease, have completed the isolation period, within 180 days from the time of recovery.
- People infected with SARS-CoV-2, self-testing, self-isolating and then recovering from the disease must be tested to prove that they have antibodies.
- 1 shot for vaccines that require 2 doses (AstraZeneca, Pfizer, Moderna, Sinopharm, Sputnik V) and 14 days have passed.
- Having negative periodic test results (every 3 days) (with confirmation according to the instructions of the Department of Health and updated in the electronic database system for card issuance and renewal).