Virus World

There’s been a lot of excitement about the potential of antibody-based blood tests, also known as serology tests, to help contain the coronavirus disease 2019 (COVID-19) pandemic. There’s also an awareness that more research is needed to determine when—or even if—people infected with SARS-CoV-2, the novel coronavirus that causes COVID-19, produce antibodies that may protect them from re-infection.

A recent study in Nature Medicine brings much-needed clarity, along with renewed enthusiasm, to efforts to develop and implement widescale antibody testing for SARS-CoV-2. Antibodies are blood proteins produced by the immune system to fight foreign invaders like viruses, and may help to ward off future attacks by those same invaders. In their study of blood drawn from 285 people hospitalized with severe COVID-19, researchers in China, led by Ai-Long Huang, Chongqing Medical University, found that all had developed SARS-CoV-2 specific antibodies within two to three weeks of their first symptoms. Although more follow-up work is needed to determine just how protective these antibodies are and for how long, these findings suggest that the immune systems of people who survive COVID-19 have been be primed to recognize SARS-CoV-2 and possibly thwart a second infection.

Specifically, the researchers determined that nearly all of the 285 patients studied produced a type of antibody called IgM, which is the first antibody that the body makes when fighting an infection. Though only about 40 percent produced IgM in the first week after onset of COVID-19, that number increased steadily to almost 95 percent two weeks later. Some of these patients also produced a type of antibody called IgG. While IgG often appears a little later after acute infection, it has the potential to confer sustained immunity. To confirm their results, the researchers turned to another group of 69 people diagnosed with COVID-19. The researchers collected blood samples from each person upon admission to the hospital and every three days thereafter until discharge. The team found that, with the exception of one woman and her daughter, the patients produced specific antibodies against SARS-CoV-2 within 20 days of their first symptoms of COVID-19.

Published in Nature Medicine:

https://doi.org/10.1038/s41591-020-0897-1

Hundreds of thousands of Los Angeles County residents may have been infected with the coronavirus by early April, far outpacing the number of officially confirmed cases, according to a report released Monday. The initial results from the first large-scale study tracking the spread of the coronavirus in the county found that 4.1% of adults have antibodies to the virus in their blood, an indication of past exposure. That translates to roughly 221,000 to 442,000 adults who have recovered from an infection, once margin of error is taken into account, according to the researchers conducting the study. The county had reported fewer than 8,000 cases at that time.

The findings suggest the fatality rate may be much lower than previously thought. But although the virus may be more widespread, the infection rate still falls far short of herd immunity that, absent a vaccine, would be key to return to normal life. “We are very early in the epidemic, and many more people in L.A. County could potentially be impacted,” said Neeraj Sood, the study’s leader and a professor at USC’s Price School for Public Policy. “And as those number of infections arise, so will the number of deaths, the number of hospitalizations, and the number of ICU admissions.” 

The early results from L.A. County come three days after Stanford researchers reported that the coronavirus appears to have circulated much more widely in Santa Clara County than previously thought....

Far more people may have been infected with Covid-19 than have been confirmed by health officials in Santa Clara County, California, according to a study released Friday in preprint. The study used an antibody blood test to estimate how many people had been infected with Covid-19 in the past. Other tests, like those performed with nasal swabs or saliva, test for the virus' genetic material, which does not persist long after recovery, as antibodies do.

"We found that there are many, many unidentified cases of people having Covid infection that were never identified with it with a virus test," said Dr. Jay Bhattacharya, a professor of medicine at Stanford University and one of the paper's authors. "It's consistent with findings from around the world that this disease, this epidemic is further along than we thought." The study estimated that 2.49% to 4.16% of people in Santa Clara Country had been infected with Covid-19 by April 1. This represents between 48,000 and 81,000 people, which is 50 to 85 times what county officials recorded by that date: 956 confirmed cases....

If 50 times more people have had the infection, the death rate could drop by that same factor, putting it "somewhere between 'little worse than the flu' to 'twice as bad as the flu' in terms of case fatality rate," Bhattacharya said.

Preprint of Original Study (April 17, 2020):

https://www.medrxiv.org/content/10.1101/2020.04.14.20062463v1 

“Immunity passports” for key workers could be a way of getting people who have had coronavirus back into the workforce more quickly, scientists and politicians in the UK have suggested. Researchers in Germany are currently preparing a mass study into how many people are already immune to the Covid-19 virus, allowing authorities to eventually issue passes to exclude workers from restrictive measures currently in place.

The study, which is yet to finalise funding, would involve testing the blood of more than 100,000 volunteers for coronavirus antibodies from mid-April. The test would then be repeated at regular intervals on an accumulatively larger sample of the population, to track the pandemic’s progress. The shadow health secretary, Jonathan Ashworth, said: “Germany appears to be leading the way in the testing and we have much to learn from their approach. I’ve repeatedly called for more testing and contact tracing in the UK, and we should be looking at initiatives like this closely.”

The results of the German study, organised by the government’s public health body, the Robert Koch Institute, the German Centre for Infection Research, the Institute for Virology at Berlin’s Charite hospital and blood donation services, would make it easier to decide when and where schools in the country could reopen, and which people are safe to go back to work. “Those who are immune could be issued with a kind of vaccination pass that would for example allow them to exempted from restrictions on their activity,” said Gerard Krause, head of epidemiology at the Helmholtz Centre for Infection Research in Braunschweig. The German government has not yet officially commented on the proposal for such a certificate made by scientists....

LabCorp (NYSE: LH), a leading global life sciences company that is deeply integrated in guiding patient care, today announced that its COVID-19 Immunoglobulin G (IgG) antibody test is now available for individuals through LabCorp.com. With the addition of this latest offering, individuals have the ability to receive the COVID-19 IgG antibody test from their doctor, in person or through a telemedicine program, and now directly using LabCorp.com.

LabCorp does not require upfront out-of-pocket costs for the IgG antibody test. If the individual uses LabCorp.com to get the test, there is a non-reimbursable fee of $10 paid to PWNHealth to cover the independent physician service costs. If the test is ordered through the individual’s doctor or healthcare provider, the $10 PWNHealth fee does not apply. LabCorp.com is a convenient option that uses an independent physician service, PWNHealth, to determine if an individual is eligible for the test following the completion of a short health questionnaire. Individuals who meet PWNHealth’s criteria can go to one of LabCorp’s thousands of patient service centers. Test results will be available through their LabCorp PatientTM account and individuals can consult with an independent licensed healthcare provider from PWNHealth. The COVID-19 IgG antibody blood test detects the presence of antibodies to the virus and can help determine if an individual may have been exposed to the virus. While antibody tests are helpful to understand if an individual has developed antibodies and a potential immune response, antibody testing should not be used as the sole basis to diagnose or exclude infection.

To order the test without referral go to: 

https://patient.labcorp.com/covid-19-antibody-test

Studies from serum samples could transform our understanding of the spread of COVID-19, but what antibodies alone say about immunity is not yet clear. It’s months into the coronavirus pandemic and public health officials still don’t know how many people have actually contracted the culprit, SARS-CoV-2. In many countries testing capacity has lagged behind the spread of the virus. Large numbers of people have developed COVID-19 symptoms but have not been tested, and the vast majority of people who had the virus but never developed symptoms and therefore were not tested, are not reflected in official statistics.

Federal and state governments, companies, and research groups are now racing to develop antibody tests to shine a light on the true spread of SARS-CoV-2. While PCR tests currently used to diagnose cases detect the virus’s genetic material, antibody tests can screen for virus-attacking antibodies that are formed shortly after an initial infection. Those antibodies usually linger in the blood long after the virus is gone. One such antibody, or serological, test was given emergency use authorization by the Food and Drug Administration in early April, and a number of other groups are making more tests, and in some cases even deploying them.

The National Institutes of Health has launched a study to detect antibodies in order to gather data for epidemiological models. And a recent survey of residents in a German town was one of the first to use an antibody test among the public, reporting that 14 percent of people there were likely to have been infected with SARS-CoV-2 due to the presence of antibodies.

Such a test may help scientists learn how widespread the infection is, and how long people remain immune after recovering. The Food and Drug Administration on Thursday approved a new test for coronavirus antibodies, the first for use in the United States. Currently available tests are designed to find fragments of viral genes indicating an ongoing infection. Doctors swab the nose and throat, and amplify any genetic material from the virus found there.

The new test, by contrast, looks for protective antibodies in a finger prick of blood. It tells doctors whether a patient has ever been exposed to the virus and now may have some immunity. That is important for several reasons. People with immunity might be able to venture safely from their homes and help shore up the work force. It may be particularly important for doctors and nurses to know whether they have antibodies. Antibody testing eventually should give scientists a better sense of how widespread the infection is in the population — and help researchers calculate more precisely the death rate.

“If we don’t know the asymptomatic or mild cases, we won’t know if it’s killing a sizable fraction of the people who have it, or only people who have underlying conditions or are very unlucky,” said Dr. Carl Bergstrom, an infectious diseases expert at the University of Washington in Seattle.  The new test, made by Cellex, looks for two types of antibodies: immunoglobulin M, made by the body a few days into an infection; and immunoglobulin G, made later but created specifically to neutralize a particular invader. The test delivers results in about 15 minutes. But just having antibodies does not guarantee immunity from the coronavirus.

FDA Approval Letter for Cellex Test (April 1, 2020): 

https://www.fda.gov/media/136622/download