By Celia Llopis-Jepsen
Perhaps two in every 50 Kansans have antibodies swimming in their bloodstream that show they’ve had COVID-19.
That relatively low number — based on the assumption that blood donors reflect the broader population — suggests a gloomy reality. Kansas is still in the early days of this pandemic and it’s looking at a future likely to bring many more cases than it has so far seen.
“Absolutely,” said Roger Shapiro, an immunologist at Harvard University’s School of Public Health. “When you look at these figures, you realize how far we are from herd immunity.”
The overwhelming number of Kansans, perhaps more than 95%, haven’t yet experienced the virus that has killed more than 200,000 Americans.
So medical pros say the only thing to do is sit tight, keep your masks on and stay away from other people, until we have a vaccine.
That, and get a flu shot.
“This is not the time to play a guessing game of, ‘Do I have the flu or do I have COVID?’” said Gigi Gronvall, an immunologist at Johns Hopkins’ Center for Health Security.
Many people still can’t get fast coronavirus tests that would let them isolate in time to stop the disease from spreading further, and hospitals remain at risk of getting overwhelmed by coronavirus and flu cases this fall.
Clues in the blood
The human body produces antibodies when exposed to a disease, to fend it off. And those microscopic defenders can stick around after recovery.
So the American Red Cross screens blood donations for antibodies against SARS-CoV-2, the virus behind COVID-19. It then sends plasma with the specialized proteins to hospitals treating coronavirus patients, and it reports how often it detects the antibodies to state health agencies trying to piece together the bigger picture.
Nationally, the Red Cross has tested about 1.2 million blood donations for the antibodies.
From mid-June to mid-September, it found them in about 2% of donations nationally. The same was true for Kansas donors. It’s not known how well that statistic might reflect the broader population.
Weekly tallies suggest the number of people carrying the antibodies has ticked upward in Kansas, as elsewhere. In recent weeks, the Red Cross reported antibodies in 4% to 5% of Kansas donations.
Could someone with antibodies catch the virus again a year from now and get seriously sick? How about two years from now? Or could they catch it, not show any symptoms, and spread the virus anyway? Scientists can’t yet say.
“This is not a get-out-of-jail-free card,” Gronvall said. If a test shows you have antibodies, she said, you should still wear a mask and follow social distancing rules.
Recent reports of a few patients catching the novel coronavirus more than once in a relatively short time may not signal what to expect for most people, but leave open the possibility that one infection doesn’t protect you against another.
The Red Cross reported in a medical journal last month that blood donations from people of color test positive for the antibodies at a higher rate than blood from white donors.
That matches other research that shows communities of color bearing the brunt of the pandemic. It likely reflects broader social and economic disparities, such as lower incomes and a greater likelihood of working high-risk jobs that involve in-person contact with many customers or colleagues in a single day.
The virus spread fast in crowded Kansas meatpacking plants, for example, that rely heavily on the labor of people of color in southwest Kansas.
The need for a vaccine
Some studies and modeling point to higher antibody rates nationally and globally than the Red Cross has seen among blood donors, but still don’t offer good news.
“The (World Health Organization) just came out with an estimate that maybe up to 10% of the world has been infected,” Shapiro said. “But even at that number, we’re still so far from achieving herd immunity. … We really need to create immunity with a vaccine.”
Vaccines mimic natural infections. They kick a person’s immune system into gear so that it churns out antibodies and stores viral information in memory cells that could defend us even after those antibodies fade. (Researchers have found SARS-CoV-2 antibodies triggered by natural infection two or even three months after infection, and say it varies from person to person.)
Ongoing coronavirus vaccine trials aim to check how protective these immune responses will prove long-term, and whether people will need booster shots over time to keep their defenses up.
Part of the benefit from vaccines will ultimately come from the sheer number of people who would gain some level of protection at once.
“As we get to high enough vaccine levels, the herd immunity will actually just lower the amount of virus that’s circulating,” Shapiro said. “There will be just less virus around. This is our hope.”
Should you get an antibody test?
The Red Cross’ free antibody tests serve three functions.
They gather the information that helps public health experts studying the virus’ spread, and they allow the Red Cross to flag plasma with antibodies for hospitals.
But either way, donations remain as critical as ever to the nation’s blood supply.
And that’s a third reason for offering antibody tests. They attract people to keep donating amid the pandemic.
The Red Cross uses respected tests, and when a blood sample proves positive for antibodies, it double-checks with a second, high-quality process.
For people who had respiratory symptoms in recent months — but couldn’t get checked for COVID-19 because of the nationwide shortage of viral tests — that may satisfy their curiosity.
And that could help keep donations flowing as the pandemic hampers traditional blood drives, such as a major annual effort that would have attracted thousands of donors next week.
“The biggest blood drive the Red Cross does across the country is at the University of Missouri in Columbia,” said Joe Zydlo, a regional communications manager in St. Louis. “And that has been canceled.”
Meanwhile, Gronvall advises against buying an antibody test somewhere. After all, the information won’t help you medically, she said, and many products are unreliable anyway.
“There’s just been so many bad tests out there,” she said. “Right now I would not spend money on it.”
Celia Llopis-Jepsen reports on consumer health and education for the Kansas News Service. You can follow her on Twitter @celia_LJ or email her at celia (at) kcur (dot) org. The Kansas News Service is a collaboration of KCUR, Kansas Public Radio, KMUW and High Plains Public Radio focused on health, the social determinants of health and their connection to public policy.
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