Forbes Link to new antibody test requirements in ChinaOn...

Forbes Link to new antibody test requirements in China

On November 6, China debuted a new travel testing policy. Before, incoming airline passengers had to submit results for a conventional PCR test that proved the absence of Covid-19 and, upon landing, head to a predetermined location for a mandatory 14-day quarantine. Now, another item has joined the list: a negative IgM antibody test result.

Let’s backtrack to basics. A standard PCR test, or “nucleic acid test,” searches the body for viral genetic material. IgM, on the other hand, is the first in a series of antibodies the body produces to defend against invading pathogens. They fade relatively rapidly, on average within five to seven weeks. Because IgM antibodies are a marker of recent infection, and because their duration is weeks long, an IgM test is more likely to screen out rare individuals who exhibit long-term virus shedding. One woman, it was found in a recent case study, had infectious virus more than 70 days after her initial diagnosis. Whether or not the Chinese government has evidence that new focal areas of infection are a consequence of long-term virus shedding, we don’t know. But it may well be the case, which is why they introduced the IgM test.