Up to four percent of the Californian population may have already been infected with a coronavirus, the results of antibody tests suggest.
Scientists at Stanford University have developed an antibody test for the coronavirus, which detects when someone has already been infected and their body has produced immune cells that can provide protection against reinfection.
They found that between 2.5 and 5.2% of people tested were positive for antibodies.
This would mean that many more people have caught a coronavirus than what is counted in the official state count which, at 28,324 cases on Friday, represents about 0.07% of the state’s population.
However, questions remain as to the accuracy of the antibody tests, as well as whether the sample of people recruited for the study via online advertisements could attract “random” test volunteers who suspect they have been infected.
Scientists at Stanford University have used the antibody test developed in their laboratory (photo) to screen 3,300 Californians for possible immunity against coronaviruses. About 4% were positive
The Stanford team developed the equivalent of a highly “precise” test, in immunological terms.
Depending on their validation process, the test is specific between 95 and 100% – which means it is excellent for detecting antibodies developed in response to the virus that causes COVID-19, and only to that virus.
The chances of him falsely identifying a person as having a coronavirus when he actually has a different infection are slim.
He’s about 80 percent sensitive, head of work research told DailyMail.com.
This means that 80% of the time that a person’s blood confirmed to have a coronavirus goes through the test, it identifies antibodies.
Despite the 20 percent who suggest it might be missing, these two measures make it a relatively good test, compared to the others and in difficult circumstances to test for antibodies to a virus that we know so little about. .
Dr. Bendavid and his team tested approximately 3,000 people in Santa Clara, California.
The test analyzes a drop of blood taken from a finger prick, which is placed on a strip of paper with lines of antibody combined with another element – often gold – along it.
Scientists across the United States, from California to Massachusetts (photo), deploy antibody blood tests to screen Americans for possible immunity to coronavirus using a finger prick
If someone has developed antibodies to the coronavirus, their blood will react with the bands along the paper, causing their colors to change.
As of Friday, about 1,800 people in Santa Clara had tested positive for the coronavirus, according to data from the tracker 1point3acres.com.
But if the Stanford test is an indicator of the infection rate, between 48,000 and 81,000 people may have already caught a coronavirus.
Scientists in the United States and around the world largely agree: Coronavirus cases are almost certainly underestimated.
However, the results of the Stanford study should be interpreted with caution.
On the one hand, someone who suspects they have had a coronavirus may be more likely to respond to an online advertisement for being tested than someone who does not think they have contracted the virus, ABC told Dr. John Brownstein, epidemiologist at Boston’s Children’s Hospital. New.
Although laboratory tests suggest that the Stanford antibody test is fairly reliable, relatively little is known about the coronavirus or the antibodies that humans make in response, and only the results of much broader antibody tests will give a clear picture of their real effectiveness. work, paradoxically.
Furthermore, even if a test was 100% specific and sensitive – correctly identifying the antibodies against the virus in each person who had it – we do not yet know, if any, what protection these antibodies offer.
Laboratory studies suggest that people develop antibodies to the virus within a few weeks and that these last for a few weeks.
But we do not yet know what level of antibody is required to provide immunity, and the duration of that immunity cannot be measured until a sufficient number of people are identified as having antibodies and followed up on. for weeks, months or even years.
Dr. Bendavid told DailyMail.com that he and his team would advise anyone tested on the ambiguity of the results.
Government officials have touted antibody testing as the key to putting Americans back – at least those who have been infected and have developed some immunity – to work.
On a positive note, if Dr. Bendavid and his team’s study are representative of the United States, and the antibodies are found to confer robust immunity, many Americans may soon be safe to return to work.
But on the other hand, Dr. Bendavid told ABC News that his data also suggests that about 95% of the population is still unprotected from coronaviruses.
Either way, the more people tested by researchers like Stanford, the quicker scientists and policy makers will have answers to desperately awaited questions about the pandemic.