Many experts see antibody testing as a key to re-opening the economy. But significant problems remain with these tests that mean we may not be able to rely on them anytime soon.
Antibody tests determine who has had the coronavirus and therefore built up immunity to it. Immunity is determined by the level of antibodies in the blood. Antibodies are proteins produced by white blood cells that fight foreign infections in the body.
There are two different types of antibodies, immunoglobulin M and immunoglobulin G. To test for these antibodies, scientists create the virus’ RNA in the lab, mix it with blood from individuals, and see if the antibodies bind to the virus.
At first glance, antibody tests seem like a great option for determining who can go back to work. There is evidence that large numbers of covid-19 carriers are asymptomatic. Therefore, many people will have had the virus without knowing it, and if this is determined they could go back to work.
Diagnostic testing, which governments are focused on at the moment, only determines whether an individual currently has the coronavirus. Antibody testing has the advantage of determining if the individual has ever had it in the past.
How Much COVID-19 Immunity is Needed to Re-open the Economy?
There is a concept called “herd immunity” that means that a certain percentage of the population has contracted a virus and the whole population is safe because of the overall immunity. For very contagious diseases, the level of vaccination or infection needed for herd immunity is over 90%. Thankfully, COVID-19 is lower on the scale of being contagious, so the level needed for herd immunity is approximately 70%.
Some have advocated opening up society to younger and healthier individuals so that herd immunity can be reached and the virus can be slowed. However, this has been dismissed by most experts because we still do not know enough about the lethality or immune resistance created by the disease. This strategy could end up leading to a huge number of deaths, and on top of that, those who do get the virus may be susceptible to it again in the near term.
Of course, the level of immunity in the population needed to open up some parts of the economy is likely lower than full herd immunity. Waiting for a vaccine in order to open up the economy is undesirable as it could take months or years before it is widely available. So what could antibody testing tell us about whether we can open up the economy?
While antibody testing may not tell us that we have herd immunity, it may tell us that the virus is less deadly than previously thought. If, for instance, the virus is only about as deadly as the flu then we would be able to open up the economy, at least partly. But large immunity testing studies will need to be done to determine this. The good news is that some of these studies have been done or are starting.
Los Angeles County recently released results of its antibody testing. They are the first major US municipality to do such a study. 1,000 residents were randomly selected to participate. The researchers found that between 2.8% and 5.6% of the population had antibodies in their blood.
Applying that number to the county’s entire population leads to an estimation of between 221,000 and 442,000 previously contracting COVID-19. This is much larger than the 8,000 confirmed cases in the county found through diagnostic testing.
The good news is that this means that the virus may not be as deadly as originally feared, because the mortality rate estimation would drop. This also means that in this county at least, nothing close to herd immunity levels have been reached.
About 4% of the population has immunity according to the study, but somewhere around 70% is needed for herd immunity. Another study in Germany estimated that 14% of the population had some level of immunity. In other words, if social distancing is relaxed, there is still a large proportion of the population that the virus could affect.
New York State is also preparing to run a large antibody testing study. 2,000 tests per day will be carried out on a random sample in the coming weeks.
Dozens of Antibody Tests Hitting the Market
The FDA in the US has loosened its policy with respect to antibody testing in the past weeks. They now grant emergency use approval to new tests, which means that they can be sold on the market, but they cannot advertise that they have been approved for use. Since this policy has come into effect, about 100 tests have flooded the market. The FDA has cautioned against using these tests as a sole factor in determining immunity.
Many companies have been able to quickly adapt their operations to manufacture antibody tests. The FDA released guidelines to aid manufacturers in producing accurate tests. Boston Heart Diagnostics is an example of a company that before the pandemic manufactured other types of medical tests, including those for heart disease. These types of tests have been less in demand since the pandemic started, so the company decided to pivot to creating coronavirus immunity tests and help those in need in these times of crisis.
Like companies re-tooling operations to create ventilators or personal protective equipment, this is an example of how having good logistics infrastructure in place can help a company change direction quickly when the market changes.
Accuracy of Antibody Testing
The biggest question with antibody tests is, are they accurate? Do they actually determine if somebody is safe from contracting COVID-19 in the future?
Since the FDA has not approved the reliability of any antibody tests for coronavirus thus far, the short answer is that they cannot be trusted at this time. The World Health Organization’s Dr. Maria Van Kerkhove says, “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”.
Some experts say that one of the problems with these tests is that the coronavirus antibodies look very much like the common cold, so the tests may mistake the two, creating false positives. Telling someone they have immunity when they do not is a very serious issue since they will likely integrate into society and, if they contract the virus or are a carrier, they could infect more people.
Logistics Concerns with Antibody Testing
We are still a long way from giving antibody tests at large scales. The world is still trying to find an accurate test and be officially approved. Labs and companies have had difficulties finding confirmed coronavirus cases in order to use their blood to verify the accuracy of antibody tests.
After finding accurate tests, manufacturing, distribution, and administration of these tests need to be scaled up quickly. Just like diagnostic testing for the coronavirus, there will be issues scaling up the production and distribution of antibody tests. When so many labs are doing the same test, supplies needed for that test come into short supply.
Labs that are accustomed to processing other types of tests will need to adapt their protocols for the new antibody tests. Unlike most diagnostic tests, the antibody tests require drawing blood from individuals and safe transportation of the blood to the lab. Logistics experts will need to work with labs, manufacturers, and healthcare providers in the development and distribution of these tests.
While antibody tests have the potential to give us more information about our readiness to reopen the economy, there is still much work to do so that these tests do not do more harm than good.