Medical diagnostic companies are racing to produce antibody testing kits in response to the COVID-19 pandemic. Governments, on the other hand, are looking to order these antibody tests kits by millions.
The challenge that national regulators and governments are facing is to strike a balance between the urgency and the day-to-day specificity and sensitivity concerns that apply to any new medical diagnostic. There are still some concerns around optimizing test design, mainly hinging on understanding the virus' behavior and neutralizing it. Yet, there's an underlying rush to limit the economic impact, to reopen borders and to resume to normal routines.
Some national regulators like the Food and Drug Administration (FDA) have already issued Emergency Use Authorization (EUA) that allows companies to start selling testing kits right away. At the moment, the FDA has approved 25 antibody tests. Health Canada has approved only one antibody test.
Antibody (serology) testing
Following the relaxation of standard assessment criteria by the regulatory bodies, companies are now rushing to produce antibody testing kits to meet the demand. The antibody test kits can be used for a range of reasons, including:
- Detecting whether someone has had Coronavirus before and has since recovered
- Revealing if vaccines are working as in intended during clinical trials
- Helping in contact tracing weeks after a suspected exposure
- Helping inform governments about the approximate number of active infections (both symptomatic and asymptomatic cases) that have occurred in the population
Antibodies are proteins that help fight off infections and can offer protection against recurrence (immunity). The serological test kits tests people's blood for Coronavirus antibodies to check whether they have already healed from the virus and if they may have developed immunity to COVID-19.
Matt Hancock, UK health secretary, on March 24, told the daily press conference that his government had purchased 3.5 million tests that would allow individuals to check if they had the virus and had since developed immunity to it so that they could get back to work. However, these China-made kits were deemed not fit for widespread use. The UK government, on May 14, approved the use of 100% accurate antibody tests, which were produced by Roche, a Swiss company.
The accuracy of COVID antibody test kits
The accuracy of COVID antibody test kits depends on a range of factors, including the duration between the onset of infection and test execution, types of antibody being assessed, and antigen specificity. Since the immune system often begins to produce antibodies within 1 to 3 weeks of a person being exposed to the virus, doing a test soon after exposure may not detect antibodies in the blood. As such, there are higher chances of getting false-negative or false-positive results.
Another factor that may affect the accuracy of the test result is cross-reactivity. Antibody tests meant explicitly for the novel Coronavirus can cross-react with related viruses like MERS-CoV, SARS-CoV, and common Coronavirus and therefore give false negative or positive results.
The positive and negative predictive values are computed using a test's specificity, its sensitivity, as well as the assumption about the percentage of people in the population who have SARS-CoV-2 antibodies. However, those interpreting results need also to consider details like diagnostic test results and clinical history to avoid false results.
So, this leads us to the big question, are COVID antibody test kits worth it?
Reasons why Coronavirus antibody tests are worth the investment
Demonstrated specificity and sensitivity
Most kits that are approved by the regulatory bodies claim to have 98-100% specificity and sensitivity. 100% specificity means that the test won't confuse other antibodies for those specific to SARS-CoV-2. 99% sensitivity, on the other hand, means that when the kit examines 100 blood samples containing the antibodies, it will detect the antibodies 99% of the time. The Roche kits, for instance, claim 100% sensitivity and 99.8% specificity.
Can help identify potential antibody donors
As we mentioned earlier on, one of the most important current use of COVID antibody test kits – en masse – is to help identify the part of the population that's been exposed previously to the virus, irrespective of whether they are symptomatic or asymptomatic. The test also shows those who have developed herd immunity after infection. This group could be a potential convalescent donor. Convalescent plasma is where blood plasma from patients who have had previous infections is artificially transferred to naïve patients to induce passive immunity.
But still, experts say that people shouldn't change any social distancing or other safety practices based on their serological test results because it's not sure whether these antibodies confer immunity or if they're likely to change clinical management. Later on, when vaccines are available, serology testing will facilitate the tracking of the immune response of those who are part of clinical trials.
People can go back to work
Experts argue that immunity-based licenses are great because they would free up those who've already contracted the disease without worsening the situation for those who haven't. Licenses are a less restrictive alternative. The current liberty-limiting measures on travel, work, and gatherings are justified because COVID-19 positive individuals may infect others, causing more deaths, illnesses, and strain on hospitals. However, these measures aren't justified when applied to those who carry little to no risk of infection.
A widely available test that delivers results in minutes would drastically change the world's strategy for dealing with COVID-19 as well as the way people live. People would be able to go back to work sooner if they are aware of their infection status. In a nutshell, using the COVID-19 antibody kits involves:
- Collecting blood sample
- Adding the blood samples to sample well
- Putting 2-3 drops of buffer in the sample well
- Reading results after 15 minutes (the time might vary depending on the type of kit)
Curb the spread of the COVID-19 virus
When more Coronavirus diagnostic tests are available, those who test positive can get early care, especially if it's symptomatic. Besides, their contacts can be traced and placed in quarantine or self-isolation to prevent further spread. COVID antibody kits make contact tracing easier, which is a big plus to preventing further spread of the virus.
Sheri Bruemmer is a seasoned industry expert with expertise in growing and managing operations that support assisted living, adult foster care, and homes for the aged communities. Sheri is a certified Gerontologist, licensed Assisted Living Director, and licensed nurse as well.