Respiratory Disease Antibody Testing

Routine screening is not necessary for ordinary healthy people, but for specific scenarios and specific groups of people, it is an extremely cost-effective clinical auxiliary diagnostic tool. Whether you should do it depends entirely on your needs and actual situation.

When respiratory diseases were on the rise in winter and spring a while ago, I was helping out at the grass-roots level of district disease control. Almost every day I met about a dozen people asking for antibody tests. There were office workers who had coughed for half a month after their fever had subsided and wanted to test for a full range of antibodies for fear that they might be exposed to the disease. There were also elderly people at home who had just had pneumonia and wanted to test for antibodies to see if they needed to get vaccinated. After many people asked, I found that people had a lot of misunderstandings about this test.

In fact, not to mention ordinary people, even the medical circle has been arguing about the value of this test for many years. Many colleagues in public health think that this thing is too cost-effective. There are at least hundreds of respiratory viruses, and there are twenty or thirty common ones that can cause symptoms. Even if you test positive for a certain antibody IgM, it may not be the culprit of the current symptoms - after all, many people may be infected with several pathogens at the same time, and the protective period of antibodies such as rhinovirus and respiratory syncytial virus can be as short as one or two months, or as long as half a year. Testing high antibodies does not mean that you will not get it again, but it can easily mislead people. I met a retired aunt last month. I heard someone said that the COVID-19 antibody test can show resistance. She spent more than 300 on the test, and the IgG value was very high. She felt that she would definitely not be infected again. She got influenza A within half a month. She came to us with the report sheet and questioned her for almost half an hour. She said that the test was not allowed to cheat money. In fact, this situation cannot be blamed on the test. It is because everyone's expectations for it are too high.

But most of us who work in clinical practice still think this test is quite practical. At the end of last year, I helped in the pediatric clinic and met a five-year-old boy who had coughed repeatedly for more than two months. Two chest X-rays did not show any major problems. He tried several antibiotics and cough medicines, but nothing improved. The parents were very anxious. Finally, we tested him for antibodies to B. pertussis and Mycoplasma pneumoniae, and found that the titer of IgM antibodies against whooping cough was particularly high. After it was clear that he was infected with whooping cough, we changed to corresponding sensitive antibiotics, and the cough basically disappeared after about ten days of taking it. For those who have had organ transplants, have been taking immunosuppressants for a long time, and the elderly who have been on long-term dialysis, we will recommend that they regularly test their influenza and pneumococcal antibody levels. If the antibody titer is not enough, they should get vaccinated in time, which can save them many sins.

As for the question that everyone is most concerned about, "Should I take the test?", there is really no need to worry. If you just have a common cold and fever, and the fever subsides in two or three days, leaving only a cough and runny nose, there is no need to take a test. Just go home and have a good rest. But if your cough and fever have not improved for more than a week, the doctor suspects that it is infection by special pathogens such as mycoplasma, whooping cough, and adenovirus. Then testing the corresponding antibodies can help to quickly make a clear diagnosis and avoid many detours. ； If you have elderly children with low immunity at home and want to know if they have hidden infections after being exposed to an infected person, or if you have just received a flu or pneumonia vaccine and want to see if it has produced enough protection, it is no problem to test the corresponding antibodies.

By the way, the packages on the market now that claim to be able to check for antibodies to more than 20 respiratory pathogens cost hundreds of dollars, so there is really no need to buy them. Think about it, you have been exposed to many pathogens as a child, and the IgG antibodies in your body are already positive. If you get a bunch of positive results, you can't tell whether you got them as a child or a recent infection. It's just a waste of money. If you really want to be tested, it is enough to ask the doctor to prescribe tests for 1-3 highly suspected pathogens based on your symptoms.

I had pneumonia last winter. After I recovered, I tested my pneumococcal antibodies and found that the titer was extremely low. I then went back to get the 13-valent pneumonia vaccine. This spring, several colleagues around me got pneumonia and took leave. I had nothing to do. I can’t say whether it was due to the vaccine, but at least I felt more at ease.

In fact, to put it bluntly, medical testing is never absolutely "useful" or "useless". To put it bluntly, it is just a tool. There is no need to deify it, and there is no need to beat it to death with a stick. If you really need it, just follow the doctor's advice. If there are no special circumstances, eating well, sleeping well and exercising more will be more effective than testing the antibodies ten times.