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Scientists are starting to roll out new blood tests for the coronavirus, a key development that, unlike the current diagnostic tests, will help pinpoint people who are immune and reveal the full scope of the pandemic.

The “serological” tests — which rely on drawn blood, not a nasal or throat swab — can identify people who were infected and have already recovered from Covid-19, including those who were never diagnosed, either because they didn’t feel particularly sick or they couldn’t get an initial test. Scientists expect those individuals will be safe from another infection for at least some time — so the tests could signal who could be prioritized to return to work or serve as a frontline health worker.


The serological tests, which are being deployed in some countries in Asia and are starting to be used at one New York hospital, could also eventually help scientists answer outstanding epidemiological questions about the spread of the virus and might even steer an inoculation strategy should a vaccine make it to market.

“We need to identify all those people here who not only knew they had the coronavirus but maybe weren’t sure because they didn’t get tested or because they had minimal symptoms,” said Christopher Kirchhoff, a former White House aide who wrote a 2016 review of the U.S. government’s response to the West African Ebola crisis. “You can imagine asking them to take the key roles in our economy to keep things moving, whether that’s manning a checkout aisle at a supermarket or taking the lead for caring for someone else in their family who comes down with the coronavirus.”

Serological tests sniff out antibodies in the blood — molecules made by the immune system in response to a pathogen’s attack.


Right now, the main diagnostic tests for Covid-19 rely on a technology called PCR and search for evidence of the virus’ RNA genome. But as people recover, they vanquish the virus from their system, so PCR isn’t helpful much beyond the infection period.

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Antibodies made in response to a virus, however, persist in the blood, acting like sentinels and rallying an immediate response should the virus try to invade again. The antibodies are unique signatures — different protectors modeled after encountering different viruses — so finding them is a signal of past contact with a particular virus.

It’s the difference between catching an invader red-handed versus going back to the crime scene and dusting for prints.

“It seems very easy to be able to say yes or no, somebody was infected or wasn’t infected,” said Florian Krammer, a virologist at the Icahn School of Medicine at Mount Sinai.

Earlier this month, Krammer and colleagues posted on a preprint server a paper describing the serological assays they had developed to detect previous exposure to SARS-CoV-2, the name of the coronavirus. (Preprints are scientific papers that have not been through the peer-review process yet.) They’ve also started a website where labs can order the ingredients they need to get tests up and running themselves.

And this week, Mount Sinai announced that antibodies detected in blood from recovered patients would be used to treat current patients. It’s hoped that injecting patients with these antibodies — a type of therapy sometimes called convalescent plasma — might provide an initial layer of protection as their own immune system kicks into gear.

Companies and academic researchers are also trying to develop plasma therapies and are scrambling to obtain blood from survivors. Serological tests could help expand the supply.

Other tests are being built as well. Researchers in the Netherlands have unveiled assays, the United Kingdom is preparing to roll out its own antibody tests, and scientists in Singapore have used them to trace chains of transmission. Robert Redfield, the director of the Centers for Disease Control and Prevention, told Congress this month that the agency was developing two serological tests; a CDC spokeswoman did not respond to messages asking for more details about the agency’s tests or its plans.

Companies have also started to sell antibody tests, though some are being framed as another tool to diagnose acute infections. Some experts are skeptical about this approach because it can take the body a few days to ramp up production of the antibodies, meaning a serological test would miss an infection if it was in its early stages.

“It takes you five, seven, 10 days — usually more than one week to develop a robust antibody response,” said Isabella Eckerle, a virologist at Geneva Centre for Emerging Viral Diseases. “And the first week is the week when people shed the virus in the highest concentrations.”

Serological tests are also critical, experts said, for painting a full picture of the virus’s spread, even if not immediately.

In other countries, researchers have started to launch “serosurveys” — testing the blood of a sample of the population to estimate just how widely the virus spread. It’s through these types of retrospective initiatives that the full number of cases can be approximated, which can help explain how common asymptomatic infections may be and calculate a better estimate for the mortality rate of a virus.

A 2015 serosurvey of the coronavirus MERS, for example, included samples from 10,000 people in Saudi Arabia. Fifteen people were found to have anti-MERS antibodies, which the researchers used to extrapolate that nearly 45,000 people in the country might have been exposed to the virus. That’s compared to fewer than 2,500 cases of MERS that have been verified around the world.

“By doing large sample serology testing, we’ll get an idea of what the scale of this pandemic was and what percentage of the population might have immunity,” said Stephen Goldstein, a University of Utah virologist.

Because the coronavirus is new, researchers cannot say for certain that an initial infection guarantees lasting protection. But based on the experience with other viruses, including other coronaviruses, they expect that people who recover will be shielded for perhaps at least a year or two, and from there the immunity might start to wane, not disappear. They would also be less likely to pass the virus on to others, so could return to work and normal life.

At a community level, if a serosurvey points to more people being immune than realized, that could signal that future waves of coronavirus cases might be less intense than some forecasts anticipate. Knowing who has immunity at an individual level could also ensure that people who have not contracted the coronavirus could be first in line for any potential vaccine. If a vaccine is eventually approved, the initial demand will likely far outpace manufacturing capabilities, so researchers expect that doses will have to be allotted in some way.

Already, several countries — including China, where the outbreak started — have begun to serosurvey, though results are not yet available. The World Health Organization has been urging countries to embark on such studies.

“We are pressuring them — not only China, all countries — to carry out these types of investigations and to share their results with us so that we can better understand how transmission is occurring,” Maria Van Kerkhove, who is helping lead WHO’s pandemic response, said this month.

  • air force inc has received authorization to import and distribute this antibody test called “covidID” it has 97% specificity and 97% sensitivity with a finger stick blood it has validation that it is 100%/100% accurate with a blood draw that is to say no false positives and no false negatives. this is a 15 min test without any additional costly reading device accept the naked eye. we have moved mountains to get this through and weare proud that we were the first to initiate doing so and be granted permission of import. since the 17th of march. we have been seeking and welcoming hospital federal state and local government procurement departments to secure their supply crucial to protecting the healthcare heroes on the front lines.our device is unique in that we implemented a database collection system to make the enemy visible. I can be reached at 6162187318 for an interview and please visit our site or email me at [email protected]


    Excellent and you are absolutely right. Read the horror story of DIamond Princess and total screw up by the Japanese Health Minister below:


    The cruise ship Diamond Princess
    A woman who had tested negative to the coronavirus when she left the Diamond Princess cruise ship later tested positive. Photograph: Athit Perawongmetha/Reuters

    Japan has confirmed that a woman who tested negative and left the coronavirus-hit Diamond Princess cruise ship later tested positive, raising more questions about the effectiveness of quarantine measures.

    The health minister, Katsunobu Kato, apologised after 23 passengers were allowed to leave the ship without being properly tested and vowed to have people retested.

    The woman in her 60s returned home to the Tochigi prefecture north of Tokyo by train on Wednesday, but she had a fever on Friday and tested positive on Saturday, a local official said.

    She was the first passenger to have tested positive in Japan after having been cleared to disembark.


    Steve White, unless you are an infectious disease expert with an and also an immunologist with a PhD, you have no business speculating about coronavirus vaccine. Access the link above so that you may learn something!

    Actually a more promising and immediate treatment would be something that can prevent entry of coronavirus into its host cells. We already have a precedent with Tamiflu that works against influenza virus. The drug BTW which was actually discovered by Gilead (but sold by Roche). Yes you are right that long term goal would be a vaccine that can allow for the immune system to produce antibody that prevent coronavirus host cell entry in a similar MOA (Mechanism of Action). But that would be at least 18 month away.

  • From what I read, there is already an effective, probably effective, vaccine against this thing – they can get the “spike”, completely separate from the virus, and inject it, and presumably get an antibody response which would very likely prevent infection.
    Though it seems very likely this would work, they are going to instead take months, they keep telling us 18 months, to completely test it.
    This seems crazy to me. As best I can guess from reading about it, it appears they are worried about ADE – Antibody Dependent Enhancement, where a previous infection with the virus makes a subsequent infection much worse, because your antibodies from the first infection are used by the virus in the second infection to infect cells they otherwise could not get into.
    So, you get Dengue once and it’s no picnic but rarely fatal -but the second time around you get hemorrhagic fever and die.
    But, reading some of the papers on it, it appears you do not the exact same strain of dengue the second time – not if you have a lot of antibodies to it. That one you are safe from -you might get another strain, somewhat antigenically different – and get infected with that, and then the ADE gets you. Maybe because of cross reactivity between your antibodies to the first infection with the second? But anyway, you do not get a strain you have very high antibodies for.

    So, apparently they had trouble with the SARS vaccine development from this same effect and that is why a lot of SARS vaccines were not developed to market – and this seems to be why they are so scared to vaccinate broadly with an experimental SARS2 vaccine – but, seems to me while it is certainly dangerous, maybe they should give out a vaccine for this one, then if there is a new strain, throw out a new vaccine for that one – again, IF you have a high titer of antibodies for the strain you are presented with, it seems you wipe them out before you get sick and ADE is a worry.
    I think we need to do something very aggressively – and if it means making guinea pigs out of a lot of people, we have to do it. I very much fear China will not let itself be paralyzed, and will come up with the vaccine first, use it, and then become the preeminent superpower.

    • I am not sure if vaccine is the answer at this point. I think we need to come up with a therapy for all infected patients, as 80% will recover without therapy but may take up to 3 weeks. The other 20% may need more supportive therapy. Vaccine is good for recurrent risk of an infection like measles, polio and more, i hope this is the first and last time for COVID19.


      Steve White. Why don’t you share your credentials and expertise or lack there of to establish the fact that you know something for real in infectious diseases, epidemiology, public health, and government policies.

      Try reading the latest and up to the minute article about coronavirus origin from the link above specifically under the section:

      Theories of SARS-CoV-2 origins

      Assuming you are capable of comprehending the text, you may finally learn something authentic and useful!

      China is at fault? Give me a break! No it’ more like inadequate government responses at hotbed hotspot countries (US, Italy, Spain, Iran, etc. ) were at fault

    • I could cite the papers I based my post on, or I could quote the eminent virologists and epidemiologists who say this outbreak originated in the live wildlife markets in Wuhan. Which do you want? Let’s give you some of both.
      1. Gabriel Leung, coronravirae expert in Hong Kong, said the virus came from an animal in the Wuhan wild animal market.
      2. Immunization with SARS coronavirus vaccines leads to pulmonary immunopathology on challenge with the SARS virus.
      Do you actually have a dispute with the papers? What is it exactly please?
      I blame the Chinese government for allowing the live wild animal markets to keep operating after the SARS outbreak. Can you find any virologist or study claiming these markets are not a hazard to produce a pandemic, exactly as the one in Wuhan did? I think everyone in virology and epidemiology knows they need to be shut down, and the Chinese government was well aware of it after the SARS outbreak. But they let it continue. The mistakes made by the rest of the world do not mean China’s government is not to blame, and, since they had about 20 years of warning, and the most control of anyone, they are the most to blame.

  • The world is pretty united in the sentiment that China made this problem much worse than it needed to be. The culture of repression, and party-first mentality allowed this problem to balloon exponentially before an effective global response was initiated.

    The world will not forget.

    PS: The US has great health care. I’ve never heard of an american travelling to China to receive care.

    • Andrew.

      Repression or individual liberty, party first or people first, democracy or socialism? I am sure coronavirus doesn’t care who they infect nor how fast they can spread!

      Effective global response? WHO screwed it up by underestimating and also with its wrong infection spread model. Did you know there is a petition to ask the WHO Chief to resign?

      Heck the close and neighboring countryof Japan acted fast enough (thanks to Prime Minsiter Abe) and it is well under control now (except for the stupid decision of the Helath Minister to allow Diamond Princess to dock at Yokohama instead of just let the ship wonder in the ocean for two weeks).

      Why don’t you show your true color and bias by emulating Trump and call it the Chinese virus!

    • I personally think the world will also not forget it was China’s fault – because it will KNOW it was China’s fault, because there is so much Chinese control over media.
      In the US, the media has condemned Trump for calling it the “Chinese virus”. They are half right, it should be called the “Wuhan Virus” or “Wuhan disease” – diseases have been identified by their place of origin – where first identified – for a long time – no one meant anything harmful by it, I mean, are American’s racist against the town of Lyme, or against St. Louis?
      But, despite the attempted cover up, we can also say China did a lot to prevent the spread of the disease, by shutting down Wuhan, which they knew was going to cost a huge amount of money. We might not have threatened the doctor trying to spread the word, but we would have failed to shut down the city, so it might be a wash.
      The main reason to critcize China is they allowed the live wild animal markets to keep operating after the SARS outbreak gave them all the warning a responsible government would have needed to shut them down. Everyone knew they were going to be the source of a pandemic sooner or later – it was just a matter of how bad the next pandemic would be – that is criminal . And it is not a matter of eating dogs or cats or unsanitary conditions within the species man has been around a long time – which can trade some diseases with us- it’s a matter of bats – and civet cats, maybe snakes, etcetera – species we have not already traded virae back and forth with for long enough to get all the really bad stuff already and have resistance.
      The trade in exotics – either wildlife or farm raised – is where the danger is. China does not need them for food, everyone knew it was going to cause a pandemic sooner or later -and, considering SARS, one that could have been worse than this one- China should pay all the world’s medical bills and pain and suffering compensation too. Of course that will not happen, the most anyone will get out of them is donations of vaccine to the really poor countries, is my guess, but, yeah, they are very much at fault but they are going to get away with it.

  • I work as a lab tech in the state of Washington. Management has said they are trying to get us the kits to do the antibody testing. As of now are normal volume is down 75%. We are literally sitting on are hands. We could be running 2-4 thousand of these ELISA tests in a 24 hr period just at our site alone . I pray we get the resources to do this testing. As a lab tech I often remind myself all of these patient tubes represent people. I treat each one like it is my moms test, but this antibody testing is at a new level not only critical for the patient but our country as well.

    • PAT…What lab do you work in? I am also in WA and have been trying to get some of these tests into the hands of someone who will try them. I have gone clear to the top at the WA DOH, UW doctors and local DOH, hospitals and clinics. They seem to be perfunctorily dismissed. Maybe because, and especially with UW, because they are trying to devise their own tests?? Can I contact you for more information??

  • Rick,

    My career encompasses more than three decades across three major global drug companies. I have been thus reading (even today) JAMA for more than 30 years. Ditto for other premier medical journals (NEJM, AIM, Lancet, BMJ). I have even summarized and analyzed highlights of key articles of relevance to my employer in relevant therapeutic areas for my colleagues on a regular basis. So please don’t give me this BS about “comprehend JAMA”.

    What about your credentials and expertise Rick? Would love to read them, or lack there of!

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