News was made this weekend when Stanford University announced a study on the coronavirus that shows the infection rate is likely larger than the number of positive cases that have been reported.  The testing was undertaken in Santa Clara County, the largest number of COVID-19 patients in Northern California.  The researchers tested 3,330 county residents, ages 19 to 64, for antibodies.  The human body creates antibodies to fight an antigen, such as a virus, and to protect itself from future infections. 

While states have been keeping a tally of the number of reported positive cases of COVID-19, it has been known since the beginning of April that there were far more people that were infected, but symptom free, by as much as 25 percent.  Knowing how many people were infected but did not get sick or had mild symptoms, rather than just the number of people who were tested positive and became sick, could change how to approach the pandemic and determine the virus’s lethality.

The Stanford researchers found antibodies existed in 2.49 to 4.16 percent the people they sampled between April 3-4, 2020.  The range exists because adjustments were made to account for demographics such as race.  With these results, the researchers estimated that between 48,000 to 81,000 people were infected in the county with the virus even though only 1,094 cases had been officially reported.  This study could lead to discovering the real denominator to determine the mortality rate.  In other words, based on Johns Hopkins Coronavirus Resource Center, total confirmed cases in Santa Clara, as of April 20, are 1,870 and total deaths are 73, which would give a mortality rate of 3.9 percent.  But using Stanford’s likely infected numbers, the mortality rate could be 0.15 or lower, a substantial difference.

Jay Bhattacharya, a co-leader of the Stanford study, wants other researchers to repeat these types of studies around the country.  He admits that Santa Clara is not representative of the country and is already planning additional tests in California.

Another study, released today by USC, found that hundreds of thousands of Los Angeles County residents may have been infected by the coronavirus.  While less than 8,000 cases had been officially reported at the start of the study, antibody testing found that approximately 2.8 to 5.6 percent of LA county residents, or 221,000 to 442,000 adults, were likely infected.  One of the study’s leaders, Neeraj Sood, a professor at USC’s School for Public Policy said, “We haven’t known the true extent of COVID-19 infections in our community because we have only tested people with symptoms, and the availability of tests has been limited… The estimates also suggest that we might have to re-calibrate disease prediction models and rethink public health strategies.”

The White House Coronavirus Task Force has been focused on more serology testing and has discussed the importance of the states doing the tests in recent daily briefings.  Today, New York Governor Andrew Cuomo announced that his state has 300 laboratories and will decide soon which ones will be doing the serology tests.  The state expects to do 10,000 antibody tests a day.

Many serology tests are in the process of being developed and distributed to testing laboratories across the country under emergency use authorization.  In an effort to get more serology tests distributed, the Food and Drug Administration (FDA) has also said it "does not intend to object to the distribution and use of serology tests to identify antibodies to SARS-CoV-2 where the test has been validated, notification is provided to the FDA, and warning statements are included with the tests, for example, noting the test has not been reviewed by the FDA."

Well-controlled trials of a representative sample of the general population would be extremely helpful in developing a good picture of the percent of Americans who had COVID-19 and have developed antibodies.  Serology tests will play a large role in determining how states will implement the Opening Up America Plan and how fast Americans gets back to work.