A worker collects a sample for a Covid-19 antibody test in Los Angeles, on August 5th.
Photographer: Patrick T. Fallon / Bloomberg
Photographer: Patrick T. Fallon / Bloomberg
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A new crop of Covid-19 antibody tests measures the level of protection one has built up against the deadly virus and can help determine which vaccines are most effective.
Siemens Healthineers AG is the first major company to receive U.S. Food and Drug Administration clearance for a test that measures the concentration of long-lasting antibodies flowing through a person’s blood. Swiss giant Roche Holding AG succeeds its own version.
Antibodies are markers of infection, and testing for them helps health officials to see how widely the virus has spread. So far, most tests can only tell if they are present. The newer ones go a step further, measuring the amount of these proteins, which are increased by the immune system to kill viral invaders.
The different Covid-19 tests and what they can reveal: QuickTake
The level of the body’s response is important in determining whether patients will develop immunity. It is also key to determining the effectiveness of faxes, as developers bring promising candidates in late-stage tests.
“You need a test that shows if a vaccine has triggered the right level of antibodies in a patient’s blood,” said Deepak Nath, chair of laboratory diagnostics at Healthineers. “It’s important to say how much of it you have.”
Fax trials
Moderna Inc. used a form of quantitative testing to show that all 45 participants in a Phase I trial of its experimental coronavirus vaccine developed antibodies. The company Phase III trial, however, is significantly larger – with about 30,000 people. And that’s just one candidate from a field of more than 160 different shots in development worldwide.
Taken together, this boom in vaccine research could create an enormous demand for quantitative testing of antibodies – and that need may grow once faxes actually gain approval, as officials have to monitor their performance, as potentially billions of people get shots. Large diagnostic companies say they are ready.
“We have talked to a lot of the fax companies and they are very interested,” said Thomas Schinecker. Roche Holding AG’s head of diagnostics said last week about a call with reporters. Roche is in the final stages of development for its quantitative test and expects to share more information in the coming months, the company said.
It has been a long and bumpy road for Covid-19 antibody testing. First, the main goal of test makers was to introduce a tool that could simply detect if someone’s immune system had fought the coronavirus, to supplement other tests that showed if they were currently infected.
Viral spread
Design a device to answer that question proved challenging enough, with many countries stocking on tests that were unreliable. Eventually, major players including Siemens Healthineers, Roche and Abbott Laboratories came forward reliable diagnostics to better understand the spread of the virus.
Officials used such tests to estimate that roughly a quarter of New York City residents were infected in April, while about 7.1% of the population was in the UK it had been since July.
To date, anti-antibody tests have typically sought evidence of a range of antibody types, including generally rapid but short-lived, and another type that appears later but provides longer protection.
The new test zeros from healthcare professionals on the latest. Once an organization like the International Federation of Clinical Chemistry and Laboratory Medicine determines what level of these antibodies is needed to confer immunity, researchers will be able to see who needs a vaccine, a booster shot or nothing at all.
Antibodies are not the only defense of the body. T cells can kill virus-infected cells, while memory cells remain for years, ready to repopulate the body with both weapons when the virus returns. Still, antibodies are the easiest to measure, making the new quantitative tests a potentially powerful way to better understand the immune system’s full response.
“What does the antibody mean as opposed to, say, the T cell mediated response?” Sei Nath. “From a research point of view, this is the first tool of its kind to do these studies.”
Spike protein
Roche has another reason to bring a quantitative device to the fore. The first antibody tests it introduced in May detects the presence of antibodies directed at the nucleocapsid surrounding the nucleic acids of the coronavirus.
However, research has shown that the most protective antibodies are those that target the spike protein that can enter virus cells. Most vaccine developers come up with shoes that encourage the body to make spike protein-related antibodies, potentially weakening the demand for Roche’s nucleocapsid product.
Roche’s quantitative test focuses on spike-protein antibodies. The company will then be able to use both of its antibody tests together, a potential advantage because a small percentage of people develop antibodies against the spike as the nucleocapsid, and not both. “You’ll get an even better understanding of what happens when you do a combination of the two,” Schinecker said.
Quantitative antibody tests can also help with treatments involving injury plasma, in which people who have already defeated Covid-19 donate their antibody-rich blood to those who are still fighting the virus.
“When five people appear in a clinic, you can take blood and say, ‘Hey, this person has more antibody to this other person and is therefore perhaps a better candidate for blood donation,'” Nath said.
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