The next big question in the COVID-19 pandemic remains antibody testing — a way to determine whether someone has been exposed to the virus and might have developed some immunity.
But antibody tests remain fraught with uncertainties. Many of the test kits now flooding the market have proved unreliable. Moreover, the experts don’t yet know for sure whether the antibodies provide immunity.
The finger-prick version of the test can yield results in 15 minutes — which would help determine who has already recovered from an infection. Labs offering antibody tests in Tucson and Phoenix have been overwhelmed with demand, and other less rigorous settings have provided mixed results. A positive antibody test might provide a sign a person’s less likely to get infected a second time. This might help determine who would face the least risk if they are tending to COVID-19 patients or returning to work.
The MHA Foundation is in the process of ordering antibody tests from South Korea, in hopes of offering testing in Payson.
Sonora Quest laboratories will perform antibody tests, which cost $65 — but only with a doctor’s order. You must schedule an appointment (https://www.sonoraquest.com/sonora-quest-laboratories-now-offers-covid-19-antibody-testing/). The lab has offices in Payson and Show Low, but most of its offices are in the Valley.
The test detects IgG antibodies, but not an active infection with the virus.
Meanwhile, the University of Arizona has announced plans to use antibody tests to screen a random sample of some 250,000 people. This would provide the first solid information on how widespread the virus has become in the state, since studies suggest half of the people infected may not develop symptoms but still spread the virus. One study in New York suggested as many as 20% of the people may have already been infected. Other studies have put the number in even some hard-hit communities at closer to 1%-5%.
A different test involving a throat swab sent to a medical lab is used to confirm an active infection. This swab test also has a problem — mostly because of the difficulty of taking a sample without triggering explosive coughing. As a result, some studies suggest that the throat-swab test may frequently miss an infection — perhaps as high as 30%. The test is more than 99% accurate when it detects an infection, but it takes days to get a result back from a lab.
The antibody test may prove useful in reopening the economy and tracking the true spread of the virus. Currently, doctors estimate the fatality rate for those who test positive with the swab tests varies from 1% to 3% — roughly 10 times the rate of a typical flu strain. However, some studies suggest 50 to 80 people are actually infected for each person who tests positive. Almost everyone tested for the active virus has serious symptoms. But if the true infection rate is 50 times the confirmed case rate, then the COVID-19 death rate might actually be similar to the flu. Some 75% of the confirmed deaths have taken place among the elderly and people with risk factors like diabetes, heart disease and other conditions.
So the antibody testing provides a way to understand the extent of the pandemic, which has killed more than 200,000 people worldwide — including 60,000 in the United States and 304 in Arizona. Studies suggest only half of the actual deaths end up in the official statistics.