Ideally, anyone worried about fading vaccine protection could get tested for Covid-fighting antibodies, the primary defense against the virus. But as cancer patients and others with impaired immune systems are learning, it\u2019s not that simple.<\/p>\n
\u201cThe good news is, we have an antibody test that can test for whether or not you\u2019ve made antibodies in response to the vaccine,\u201d said Craig Bunnell, chief medical officer at the Dana-Farber Cancer Institute. \u201cThe bad news is that we don\u2019t yet know how to interpret the results.\u201d<\/p>\n
The gap in knowledge and testing raises the prospect of heightened anxiety in the coming months for vaccine recipients wondering if they\u2019re still protected — anxiety that could curb willingness to venture out in public. That in turn could put a renewed drag on the global economic recovery.<\/p>\n
Scientists are racing to\u00a0figure out<\/a>\u00a0the so-called correlates of protection against Covid; in other words, which test results assure immunity.<\/p>\n New data<\/a>\u00a0is coming out almost weekly that brings researchers closer to understanding which immune signatures reflect protection, said epidemiologist Michael Mina of the Harvard Chan School of Public Health. But it\u2019s likely to be months before the picture is clear, he said.<\/p>\n It\u2019s also not yet known how long the vaccines last in general. They\u2019re so new that there hasn\u2019t been time to follow recipients for very long;\u00a0mounting evidence<\/a>\u00a0suggests the antibody protection lasts\u00a0at least six months<\/a>, but beyond that remains unclear.<\/p>\n It\u2019s the sort of post-vaccine limbo that those with impaired immune systems already know well.<\/p>\n \u201cImmuno-compromised\u201d people make up an estimated\u00a03% of the population<\/a>,\u00a0including people<\/a>\u00a0with blood cancers — more than\u00a01 million survivors<\/a>\u00a0in the U.S. — as well as those with autoimmune diseases, HIV and transplanted organs requiring anti-rejection drugs.<\/p>\n Michele Nadeem-Baker embodies their dilemma. She\u2019s fully vaccinated and chafing to fully return to the world after more than a year as a self-described \u201cbubble woman\u201d who leaves home in Boston\u2019s hilly Charlestown neighborhood only to take walks.<\/p>\n While new guidance from the U.S. Centers for Disease Control and Prevention lets other Bostonians rip off their masks outdoors and resume almost-normal lives, little changes for her. Her weak immune system means being vaccinated doesn\u2019t guarantee protection, and she sees no end to sheltering in place.<\/p>\n \u201cI\u2019m being told I can\u2019t get back into life,\u201d she said. \u201cHow can I find out for sure if I can? The only way to do that would be to get some scientific proof.\u201d<\/p>\n So last month, Nadeem-Baker, who has leukemia and is a cancer patient advocate, asked to be tested for coronavirus antibodies. The results: more frustration. Though she did have some of the disease-fighting proteins, she said, her doctors told her she needed to keep acting as if she didn\u2019t, because they couldn\u2019t confidently interpret her score.<\/p>\n In the body\u2019s\u00a0complex array of defenses<\/a>\u00a0against germs, antibodies act like the scouts, identifying and targeting intruders. They have powerful back-up troops, including\u00a0\u201cmemory\u201d B cells and T cells<\/a>\u00a0that ramp up to combat enemies they recognize. So antibody tests tell far from the whole story.<\/p>\n Say that \u201cJohn Doe has an antibody level of 14 or 40 or 400 or 4,000,\u201d said Harvard\u2019s Mina, an authority on testing and antibodies. \u201cThose numbers don\u2019t mean anything.\u201d<\/p>\n Establishing which antibody levels are enough for robust protection will require testing many people over time to determine when the virus can break through, he said.<\/p>\n Then again, a patient may have none of the specific antibodies measured but still have protection from other elements of the immune system, like those B and T cells. Or it could turn out that the specific antibodies being measured are not actually key to killing the virus, Mina added — something like hundreds of bits of duct tape that are stuck all over an enemy\u2019s body but not over their nose and mouth, and so are not fatal.<\/p>\n Among blood-cancer patients, more than 2,000 — including Nadeem-Baker — have\u00a0signed up<\/a>\u00a0for free antibody testing as part of a study by the Leukemia & Lymphoma Society, said the national non-profit\u2019s chief scientific officer, Lee Greenberger.<\/p>\n \u201cThe research is happening as fast as it possibly can, so we understand the magnitude of the problem, and then figure out solutions for how we\u2019re going to protect these patients,\u201d he said.<\/p>\n Early findings in cancer patients illustrate how dramatically Covid antibody responses vary by individual and by condition, Greenberger said. In one type of cancer, \u201c40 or 50% of patients don\u2019t make antibodies,\u201d he said. \u201cIn another blood cancer, everybody makes antibodies.\u201d<\/p>\n Among healthy volunteers, almost all get robust antibody test results, he said, but because other arms of the immune system could offer protection, it\u2019s still unclear\u00a0what even a zero-antibody test result means<\/a>, except that \u201cit\u2019s a warning sign.\u201d<\/p>\n The upshot remains so murky that the CDC explicitly\u00a0says<\/a>\u00a0\u201cantibody testing is not recommended for assessing immunity\u201d after vaccination in people with immune issues.<\/p>\n Dana-Farber similarly\u00a0cautions<\/a>\u00a0cancer patients that \u201cunfortunately, there isn\u2019t any way to know with certainty whether the vaccine worked.\u201d<\/p>\n \u201cAs we gain more understanding of the test results, their meaning, and how to respond to those results, we may find that testing becomes useful,\u201d it said. \u201cUntil then, we recommend getting vaccinated and continuing to exercise precautions to reduce the risk of exposure.\u201d<\/p>\n Also still to be determined: How the general public will react if immunity seems to be fading and testing remains inconclusive, particularly if — or rather, when, epidemiologists say — new outbreaks arise.<\/p>\n The economic impact is likely to be limited in countries with high vaccine uptake because any new outbreaks are likely to be localized, said John Ricco from the Penn Wharton Budget Model, which has been analyzing the economic impact of vaccines. But the prospect underscores one consistent finding, he said: \u201cDollars spent on any sort of vaccine research at this point have a very high return on investment.\u201d<\/p>\n Research on new tools for measuring immunity is rapidly advancing, said Harvard\u2019s Mina, whose lab is working on them and runs tens of thousands of antibody tests a week.<\/p>\n He envisions mass testing to monitor immunity for Covid and other viruses — both for individual awareness and for public health. But for that, antibody tests would need to be much cheaper than the current $120 or so, he said.<\/p>\n Though there are several tests on the market, \u201cIf somebody is telling you that they\u2019re giving you an idea of how protected you are, I would say, don\u2019t believe them,\u201d he said.<\/p>\n Weavr Health<\/a>, a startup based in Cambridge, Massachusetts, is among companies preparing for when that changes. It\u2019s applied for emergency use authorization for an at-home, 10-minute antibody test.<\/p>\n Chief Executive Officer Linh Hoang cites\u00a0recent research<\/a>\u00a0that found people who test negative for Covid antibodies have a ten-fold higher risk of catching Covid than people who test positive. He argues that though it\u2019s too early to interpret test results, indications are strong that antibodies offer \u201csome level of protection,\u201d something like an \u201cinternal mask.\u201d<\/p>\n People register to receive Covid-19 vaccines at a site in Richmond, California, on April 15.<\/p>\n Photographer: David Paul Morris\/Bloomberg<\/p>\n \u201cThe question mark is: What is the role of antibodies?\u201d he said. \u201cIs it like an N95 internal mask or a surgical mask? And maybe it varies from individual to individual.\u201d<\/p>\n Once it\u2019s clear what antibody test results mean, more research must determine how best to treat patients who get scant protection from vaccines, said Greenberger.<\/p>\n Options include giving patients antibody cocktails or possibly additional or different vaccines, he said. He has heard of a couple of patients quietly getting a third vaccine shot but cautions that all medical treatments must be tested carefully in clinical trials.<\/p>\n In Boston, Michele Nadeem-Baker waits hopefully for more certainty about both tests and treatments.<\/p>\n \u201cIt\u2019s not over yet for some of us,\u201d she said, \u201ceven if we get vaccinated.\u201d<\/p>\n More stories like this are available on\u00a0bloomberg.com<\/a><\/p>\n \u00a92021 Bloomberg L.P.<\/p>\nNot a Good Sign<\/h3>\n
\u2018Don\u2019t Believe Them\u2019<\/h3>\n
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