The Centers for Disease Control and Prevention is developing tests that could provide public health officials crucial information about how broadly the coronavirus has spread in the United States, even among mild cases or people without symptoms, the agency’s director said Wednesday.

The serologic tests, which are different from the ones used to diagnose active infection, would allow researchers to test the blood of people who were not confirmed cases of Covid-19 in communities where the virus spread. They would be designed to look for signs that people have mounted an immune response after being exposed to the virus.

CDC Director Robert Redfield told Congress that the agency is working on two of these types of tests. “CDC has developed two serological tests that we’re evaluating right now so we can get an idea through surveillance what’s the extent of this outbreak, how many people really are infected,” he told a House panel. “That is being moved out now to do these extensive surveillance programs.”


Understanding the full scope of an outbreak would allow authorities to learn more about how the virus spreads. It would also provide a more accurate picture of the so-called infection fatality ratio, or, in layman’s terms, the percentage of cases that are fatal. The figure is arrived at by taking the number of deaths and dividing that by the number of cases, so if many thousands of cases are not accounted for, it can make a disease appear more lethal than it actually is.

We want to hear from you: Are you a health care worker affected by the coronavirus outbreak? Please tell us about your experience.

Researchers in China and Singapore have also developed serologic tests and have initiated these types of studies, according to the World Health Organization. The agency has called on all countries with cases to conduct this kind of epidemiological work.


“These types of studies should be conducted now,” Maria Van Kerkhove, who heads WHO’s emerging diseases and zoonoses unit, recently told STAT. “This is one of the major things that needs to be done now. And everywhere. Not just in China. In the U.S., in Italy, in Iran — that would give us a better understanding of where this virus is and if we’re truly missing a large number of cases.”

She added: “Until we have population-based sero-surveys, we really don’t truly know.”

At a press briefing in Geneva Wednesday, Van Kerkhove called for the public sharing of the results from serologic studies and said the WHO hopes to have some data in the coming weeks from China.

“It will take some time,” she said. “We do need to give them the time to run these sero-epi investigations.”

  • I was ill from 1/24-1/30. However, I didn’t feel healthy for another 1-2 weeks after. I had a fever, sneezing, was using an inhaler every 4-6 hours because I couldn’t breathe very well. If we knew what we know now, I would’ve been at a doctors office or ER, after I called in. I’d be interested in taking a serologic test. I’m in the ATL area.

    • Michael Rogers,

      Thank you for providing an excellent test case and testimonial.

      Few lessons still NOT learned by all:

      1. According to the latest issue of Lancet (one of the most prominent medical journals in the world), the doctors at Wuhan found that even for those patients fully recovered, they found “viral shedding” of median duration was 20 days and as long as 37 days. SO obviously, the current 14 days of recommended or even mandated 14 days is IMO woefully inadequate.

      2. Several Diamond Princess passengers in Yokohama, Japan was allowed to disembark even with negative test but subsequently found to be positive. So once again the current protocol of test, positive, quarantine for 14 days, no symptoms, release is inadequate. Even after 14 days, formerly positive patients MUST be retested and if negative, then be allowed to travel or be released.

      Do we hear anything about longer incubation period” or “quarantine period” of 14-days?

      3. What happens with a suspected bomb threat or active shooter in a school? Very simple, the law enforcement authority and even some progressive schools proceed with the inevitable and effective “lock down”. until the situation is resolved.

      Do we hear anything about quarantine period longer than 14 days or yheneed for retesting or possible lockdown of an entire city, communiiy, or even a state??

      Sadly, afraid not even from Anthony Fauci nor Trump!!

      Drastic times require drastic measures. Heck they are doing so in Italy, right? Screw individual liberty and freedom to travel! Draconian and authoritarian measures in China did work, right? Can we Americans stomach or tolerate these measures?

    • The measures in China have not “worked” in the sense of getting the communities over the disease. They have slowed the spread by restricting communities to a degree that will not be sustainable for months on end. If these restrictions were to be lifted community spread would pick right back up, but this isn’t some sort of Doomsday virus. Many people get over it with no more trouble than the flu. The more they test for it the lower the mortality rate goes, not because of some sort of cure or treatment, but because when testing is extended outside of the group of people who have shown up at the hospital many non-life threatening cases are discovered.

  • I want this test. If the virus was active in China in November there is no way it has just now made it to the US. I was very very ill January 25th. Tested negative for flu. My blood work was off as well and I was told the flu woukdbt cause my blood work to be off. Now I’m seeing studies of the people with covid19 that have the same things off in their blood work as I did. O couldn’t breath, fever of 103.5, I really thought I would die. I’d love to know if I had the infection already so that I could donate plasma with antibodies to help save lives .

    • Stephanie:
      I was also sick from 20-25 January with 103 fever, dry cough and severe fatigue. I test negative for flu of any kind. My 16 year old daughter was then sick on 31 Jan and in the Urgent Care by 1 February with high fever, dehydration, racing heart rate, and her blood work revealed anemia and she was not positive for any flu either. I was sick in Virginia. She was sick in Hawaii. We were probably super spreaders. I am so sad about all of this and I want to know if we are indeed survivors I want to be counted and I want to be of help. If we are immune now, we should be helping in our community.

    • What tests was off for this new virus?? I had (dr don’t know why) was in hospital in December. Flu tests negative. 103.4 temp for three days then finally was going down. I have never smoked or had any lung problems till now. I had to use oxygen at hospital. Now lungs are damage, I get out of breath easy and have to use inhaler everyday plus a rescue one. No reason why. They ran so many tests all negative but some were all messed up.

  • I caught a respiratory from a work colleague coughing and spluttering beside me on Feb 12th. Mailed my manager to complain about illness & hygiene discipline on the day. This was two weeks before the first case in my state, so I said it’s probably a cold but things might change VERY quickly and our habits have to change.

    2 days later got a temp & sniffle & tickly throat, on Friday 14th night. Sat in bed and temp cleared Sunday.

    Then came the mucus goop. Thick, like overcooked sauce welded to a saucepan. Couldn’t move it, stuck like glue. First in the sinuses, moved down to the throat for a week. Then moved to chest goop. One night got frightened, thought my lungs were coated and diaphragm and tummy muscles felt tired.

    Panicked I broke it down with repeated steam inhalation, kettle into a bowl under a towel, and it started to shift and clear. Still getting a few aches a month later, but lungs and respiratory tract feel clear now.

    No idea if I had it. No foreign travel or connection to “known cases”. As I said, caught it well before the first case in the state. But that goop was unlike anything I’ve ever had before.

    • Apparently Covid-19 is a dry cough and not a productive dough. If you had mucus production, it was probably just a normal flu or cold virus.

  • CDC head Dr. Refeld says CDC is working on two serological tests. But CDC has already shown it cannot properly assess whether its tests work. CDC should be forced to have FDA review its tests before they are allowed to be distributed. I would not trust the CDC tests if FDA has not cleared them for use.

    • Mary,

      Don’t you trust Roche? They are probably the most respected drug company that makes diagnostic kits in large quantities.

  • I think I have a mild case but despite CDC lifting their restrictions (travel criteria or known contact), my health provider, Kaiser will not order the test. There are several positive cases with varying symptoms which include body aches, runny nose, etc but they are screening those out. Why are they allowing milder cases to go untested, undetected and enabling community spread??

    I agree Dr Redfeld should be fired along with HHS Azar and FDA should be held accountable for massive screw ups. But their delays and mistakes, failure to anticipate the need has already cost lives of loved ones. All in an effort to keep the numbers low, the way Trump wants. This is gross incompetence and malpractice on the part of the federal government. Dr Fauci is the only doctor we can trust.

  • Kudo’s to you Travis!

    Tony Fauci responded to a similar question from Nora during the CBS Evening news and I am adding to what he said:
    1. Contact your PCP
    2. Contact you local community’s official public health officer.
    3. Contact your health insurance provider’s CMO.
    4 Contact your local newspaper’s health writer/reporter.
    5. Ditto for your local TV station’s health reporter.
    6. Contact your Congress rep.
    7. Contact the CDC directly.

  • I am a poker player in Las Vegas. The last week of January I had high fever for 2 days (104), body aches, severe respiratory phlegm that made me short of breath and painful to cough up. I tested negative for the flu but at the time Covid 19 was not even on anyone’s mind here to my knowledge. I was playing in a poker game with several sick guys with a cough. They were from the presumptive country of origin. I read about how important these seriological tests are for research on the virus and I’d love to help out and get tested but can’t find anything on who or where some of these studies will take place. Any thoughts?

  • I live in Nashville and I think that I already had the virus and recovered. I think it was around the end of January and it was pretty awful. Of course I thought it was the flu but it was different in a few ways. I would love to see widespread serological testing.

    • Congratulation for surviving and overcoming Corvid19 Bridget! Care to share your age, symptoms, how long did you take to recover, and whether your family members or for that matter anyone who had close contact with you were tested or quarantined?? Most importantly, how did you get the virus (what was the suspected source)? Du=oid ouir doctor or local helath authority require you to do any contact tracking? If they did not, then they did not do their job and should be censured IMO!

  • This is pathetic. Dr. Anthony Fauci was interviewed by


    Norah O’Donnell during tonight’s CBS Evening News Interview and he said “we don’t have the infrastructure to do thousands of tests”. And I thought the US supposedly had the best healthcare system in the world? Shame, shame, shame. What a joke!

  • Seriously? They can’t even get enough tests out for simple corona virus testing. They (the CDC) are complete mess ups with the way they have treated this viral outbreak. I would not trust a thing they say.

    • The US needs to import test kits from China where they are running 1.5 million tests per week. But CDS and/or Dept. HHS can’t afford the tariffs.

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