Medical laboratory scientist, Alicia Bui, runs a clinical test in the Immunology lab at UW Medicine, University of Washington, looking for antibodies against SARS-CoV-2, a virus strain that causes coronavirus disease (COVID-19) on April 17, 2020 in Seattle, US. Image Credit: AFP

How soon can a COVID-19 patient return to normal life? Antibody tests could provide the answer, that’s what some experts say. They surmise that if there are antibodies in the blood of persons who have recovered from coronavirus infections, those people will have some level of immunity.

Immunity against the virus SARS-CoV-2 is a grey area. Nobody knows how long will the acquired immunity last. Even if they develop immunity, how do we explain the cases of reinfections?

So what’s all the buzz about antibody tests? Around one-third of the world is some form of lockdown, and that’s battering the global economy. Politicians are eager to get the businesses going so that the economy can start humming. For that, people have to return to work. And antibody tests are seen as the passport for a patient to return to normal life. Which is why countries around the world are racing to develop antibody tests in the hope that lockdowns can be lifted.

What are antibody tests?

Antibody tests, or serology tests, are simple tests that use a few drops of blood to detect whether a person has developed antibodies and possible immunity from the coronavirus. They are easy to administer and don’t require healthcare workers to wear special equipment.

Results are out in about 15 minutes. It’s more like pregnancy tests and HIV antibody tests. A typical kit includes a needle (to prick the finger), a mixing stick, and a test solution.

What are diagnostic tests?

Diagnostic tests that are used to determine whether someone has COVID-19 infection involves taking samples of mucus and saliva. The samples are tested in a lab to see whether they contain the virus’ genomic sequence. The results can take a day or two. But they are very reliable.

Antibody tests, how accurate are they?

At the moment, their accuracy is very patchy. Britain has bought 3.5 million antibody tests from China but found it unreliable to use.

In Geneva, WHO epidemiologist Maria van Kerkhove said: “Right now, we have no evidence that the use of a serological test can show that an individual has immunity or is protected from reinfection.”

But several leading scientists are optimistic. Anthony Fauci is one. The director of the US National Institute of Allergy and Infectious Diseases told CNN that he “willing to bet anything that people who recover are really protected against reinfection.”

Fauci seems to receive support from other researchers as well. Florian Krammer, a professor in vaccinology at Mount Sinai’s Icahn School of Medicine, and George Miller, a professor of paediatrics and epidemiology at the Yale School of Public Health, too believe the serology (antibody) tests can help patients restart normal lives.

Which antibody test is reliable?

Right now, none of the antibody tests is accurate. We could be “months away from identifying a functional coronavirus antibody test which would allow millions of people to return to work,” John Bell, a professor of medicine at Oxford University, England, says.

“People don’t understand how dangerous this test is,” said Michael T. Osterholm, an infectious disease expert at the University of Minnesota, US, told the New York Times. “We sacrificed quality for speed, and in the end, when it’s people’s lives that are hanging in the balance, safety has to take precedence over speed.”

How can antibody tests help?

Antibody tests may not be accurate, but doctors say it could be used as part of a broader range of care.

Dr Ida Bergstrom, based in Washington, told the New York Times that the rapid tests could be “one tool” in the arsenal against the virus.” Antibody tests can help find out how many people have been infected with the virus.

Positive results, while not “a free licence to run around and do whatever you feel like,” can help clear someone to move forward, the Times quoted Dr Syed Ashraf of Northern Virginia as saying.

Which countries plan to use them?

The United States intends to roll out its line of tests soon. Several pharmaceutical companies in the US are developing their tests.

Germany, one of the European countries that have managed to flatten the curve, plans to send out antibody tests to residents soon. Australia too is serious about testing, having ordered 1.5 million tests.

How long can the immunity last?

No one is sure exactly how long resistance to COVID-19 might last. Writing for Bloomberg Opinion, Joe Nocera and Max Nisen say: “Acquired immunity to viruses can vary from person to person based on the severity of the infection and the strength of their immune response. Antibodies to SARS last a long time in infected people, but since that outbreak fizzled out quickly it’s unclear how protective they are. Immunity to mild coronaviruses that cause common colds can last less than a year.”

Higher levels of antibodies mean a more robust physiological response, but it is unclear in the case of the new coronavirus. Nobody knows how long the immunity will last.

The dangers and lure of quick buck

Many pharma companies see the antibody tests as a goldmine. Several Chinese companies have been accused of churning out rapid test kits which return inaccurate results. That’s something Britain learned to their dismay.

Given the urgency of the situation, the Food and Drug Administration in the US has eased the rules, allowing antibody tests to be sold without federal approval. That has prompted more than 90 companies to leap in the fray. None of them has yet produced a reliable test.

The risk returning too soon

A person who has tested positive for the new coronavirus should generally expect a substantially reduced risk of contracting the virus again. But there are no guarantees that the antibodies against SARS-CoV-2 will make the person completely immune.

Even if the antibodies protect the recovered person, that person may still have the virus in their system and pass it to others. So the antibody test is of no help as this person cannot be allowed to resume a normal life.

Some political leaders are in a hurry to reopen their countries, but it is unlikely that antibody tests will help meet their expectations in the immediate future.