Up to 30% of coronavirus patients hardly develop antibodies
Up to 30 percent of coronavirus patients may not develop enough antibodies to provide them with any protection against reinfection, a recent study suggests.
The Trump administration has repeatedly pointed to the results of antibody testing as an important signal for when the US can be reopened.
But experts have warned that disparate antibody tests are used in the United States, many of which have not been carefully validated, and that even if they accurately identify the antibodies, it is not yet clear what protection those immune cells provide.
Researchers at Fudan University in China found that nearly a third of the patients they tested had such low levels of coronavirus antibodies that they were unlikely to have any meaningful immunity to reinfection.
Antibody testing of 175 recovered Chinese coronavirus patients found that about 30 percent had so few antibodies that they could not be detected.
Immunity exists along a spectrum. It’s not something someone does or doesn’t have, but it comes in levels.
Our body produces many powerful antibodies when we encounter some viruses or bacteria, but only low levels of antibodies that quickly disappear in response to others.
The first wave of antibodies rolled out in the U.S. simply discovered whether or not it was each antibodies were present.
More advanced antibodies measure levels of these antibodies, or titers, that tell science how highly concentrated antibodies are in a blood sample.
Simply put, the higher the concentration of antibodies in a person’s blood plasma, the stronger the immune response and protection against future coronavirus reinfection will be.
This comes with the caveat that some antibodies just don’t work as well to neutralize the invader (called an antigen) they made to fight.
Dr. Anthony Fauci said ‘we have a way to go’ before antibody testing is reliable enough to tell Americans if they can get back to work without fear of reinfection with COVID-19
And antibodies also linger in the blood serum for different durations.
Many questions remain about what these tests really tell us and how accurate they are, and Dr. Anthony Fauci of President Trump’s Coronavirus Task Force warned “we have a way to go” before we can suspect much about the tests in the US .
To try to answer some of these questions, the Fudan University researchers conducted antibody tests on the blood plasma (the part of the blood in which antibodies are found) of 175 Chinese people who tested positive for COVID-19 and recovered.
Their confirmed diagnoses and recovery meant that the scientists expected these recovered patients to have detectable antibodies.
The patients in the study ranged from 15 to 85 years of age, and people of different ages had different antibody levels.
Older and middle-aged patients had significantly higher plasma [antibody] titers … than young patients, ‘the study authors wrote.
In addition, 10 patients had such low levels of antibodies that they were undetectable by the investigators’ test, although they presumably had some because they had had the coronavirus and recovered.
On average, the patients developed antibodies within 10-15 days after infection, suggesting that their bodies fought the disease within two weeks and had developed a degree of immunity to it.
But worryingly, about 30 percent of the patients tested had very low levels of antibodies.
Scientists don’t have enough data yet to know how low is too low to protect against reinfection, but it’s safe to say that the fewer antibodies a person produces, the less immune they are to coronavirus.
Most patients – about 40 percent – had a medium level of antibodies and 14 percent had a high level.
For example, while the weak antibody response may be a key in the plan to use antibody tests to help reopen the US in nearly a third of patients, the Chinese study was relatively small and the authors may point out that other parts of the immune response are at play a major or greater role in the recovery of patients from the coronavirus.
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