Scientists usually advise against testing for antibodies after vaccination. But for some people, this makes sense.
Now that tens of millions of Americans are vaccinated against the coronavirus, many people want to know: Do I have enough antibodies to keep me safe?
For most people, the answer is yes. This has not stopped the influx of local boxed documents for antibody testing. But in order to get a reliable answer from the test, the vaccinated person must undergo a specific type of test at the right time.
Test prematurely, or rely on a test that looks for the wrong antibody—which is too easy considering the dizzying array of tests available today—you might think that you are still vulnerable when you don’t have one.
In fact, scientists prefer that ordinary vaccinated people will not undergo antibody testing at all, because this is unnecessary. In clinical trials, the US-licensed vaccine caused a strong antibody response in almost all participants.
“Most people shouldn’t even worry about this,” said Akiko Iwasaki, an immunologist at Yale University.
But antibody testing is essential for people with weakened immune systems or those taking certain medications – this broad category includes millions receiving organ donations, suffering from certain blood cancers, or taking steroids or other suppressive immune systems. People with drugs. There is increasing evidence that a large proportion of these people will not develop an adequate antibody response after vaccination.
If you have to be tested, or just want to be tested, then getting the right test is essential, Dr. Iwasaki said: “I’m a bit hesitant to recommend everyone to be tested, because unless they really understand the role of testing, people It may mistakenly believe that no antibodies have been produced.”
In the early days of the pandemic, many commercial tests were aimed at finding antibodies against the coronavirus protein called nucleocapsid or N, because these antibodies are abundant in the blood after infection.
But these antibodies are not as strong as those needed to prevent viral infections, and their duration is not that long. More importantly, antibodies against the N protein are not produced by vaccines authorized by the United States; instead, these vaccines provoke antibodies against another protein (called spikes) located on the surface of the virus.
If people who have never been infected with the vaccine are vaccinated and then tested for antibodies against the N protein instead of antibodies against the spikes, they may be roughed up.
David Lat, a 46-year-old legal writer in Manhattan who was hospitalized for Covid-19 for three weeks in March 2020, recorded most of his illness and recovery on Twitter.
In the following year, Mr. Rattle was tested for antibodies many times-for example, when he went to see a pulmonologist or cardiologist for follow-up, or donated plasma. His antibody level was high in June 2020, but steadily declined in the following months.
Rattle recently recalled that this decline “does not worry me.” “I have been told that they will fade away naturally, but I am glad that I still maintain a positive attitude.”
As of March 22 this year, Mr. Lat has been fully vaccinated. But the antibody test conducted by his cardiologist on April 21 was barely positive. Mr. Rattle was stunned: “I thought that after a month of vaccination, my antibodies would burst.”
Mr. Rattle turned to Twitter for an explanation. Florian Krammer, an immunologist at the Icahn School of Medicine at Mount Sinai in New York, responded by asking what kind of test Mr. Rattle used. “That’s when I saw the test details,” Mr. Rattle said. He realized that this was a test for N protein antibodies, not antibodies against spikes.
“It seems that by default, they only give you nucleocapsid,” Mr. Rattle said. “I never thought of asking for a different one.”
In May of this year, the U.S. Food and Drug Administration advised against using antibody tests to assess immunity — a decision that attracted criticism from some scientists — and provided only basic information about the test to healthcare providers. Many doctors still don’t know the difference between antibody tests, or the fact that these tests only measure one form of immunity to the virus.
Usually available quick tests will provide yes-no results and may miss low levels of antibodies. A certain type of laboratory test, called the Elisa test, can make a semi-quantitative estimate of spike protein antibodies.
It is also important to wait at least two weeks for testing after the second injection of Pfizer-BioNTech or Moderna vaccine, when antibody levels will rise to a level sufficient for detection. For some people who receive the Johnson & Johnson vaccine, this period may be as long as four weeks.
“This is the timing, antigen and sensitivity of the test-these are all very important,” said Dr. Iwasaki.
In November, the World Health Organization established antibody testing standards to allow comparison of different tests. “There are a lot of good tests now,” Dr. Kramer said. “Little by little, all these manufacturers, all these places that run them are adapting to international units.”
Dr. Dorry Segev, a transplant surgeon and researcher at Johns Hopkins University, pointed out that antibodies are only one aspect of immunity: “A lot of things happen under the surface that antibody tests cannot directly measure.” The body still maintains the so-called cellular immunity, which is A complex network of defenders will also respond to intruders.
He said, however, for people who have been vaccinated but have a weakened immune system, it may be helpful to know that protection from the virus is not what it should be. For example, a transplant patient with poor antibody levels may be able to use test results to convince an employer that he or she should continue working remotely.
Mr. Rattle did not seek another test. Despite his test results, just knowing that the vaccine is likely to increase his antibodies again is enough to reassure him: “I believe the vaccine is effective.”
Post time: Jun-23-2021