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Study of Healthcare Workers Shows COVID-19 Immunity Lasts Many Months

Posted on by Dr. Francis Collins

Healthcare Workers
Credit: iStock/SelectStock

Throughout the COVID-19 pandemic, healthcare workers around the world have shown willingness to put their own lives on the line for their patients and communities. Unfortunately, many have also contracted SARS-CoV-2, the coronavirus that causes of COVID-19, while caring for patients. That makes these frontline heroes helpful in another way in the fight against SARS-CoV-2: determining whether people who have recovered from COVID-19 can be reinfected by the virus.

New findings from a study of thousands of healthcare workers in England show that those who got COVID-19 and produced antibodies against the virus are highly unlikely to become infected again, at least over the several months that the study was conducted. In the rare instances in which someone with acquired immunity for SARS-CoV-2 subsequently tested positive for the virus within a six month period, they never showed any signs of being ill.

Some earlier studies have shown that people who survive a COVID-19 infection continue to produce protective antibodies against key parts of the virus for several months. But how long those antibodies last and whether they are enough to protect against reinfection have remained open questions.

In search of answers, researchers led by David Eyre, University of Oxford, England, looked to more than 12,000 healthcare workers at Oxford University Hospitals from April to November 2020. At the start of the study, 11,052 of them tested negative for antibodies against SARS-CoV-2, suggesting they hadn’t had COVID-19. But the other 1,246 tested positive for antibodies, evidence that they’d already been infected.

After this initial testing, all participants received antibody tests once every two months and diagnostic tests for an active COVID-19 infection at least every other week. What the researchers discovered was rather interesting. Eighty-nine of the 11,052 healthcare workers who tested negative at the outset later got a symptomatic COVID-19 infection. Another 76 individuals who originally tested negative for antibodies tested positive for COVID-19, despite having no symptoms.

Here’s the good news: Just three of these more than 1400 antibody-positive individuals subsequently tested positive for SARS-CoV-2. What’s more, not one of them had any symptoms of COVID-19.

The findings, which were posted as a pre-print on medRxiv, suggest that acquired immunity from an initial COVID-19 infection offers protection against reinfection for six months or maybe longer. Questions remain about whether the acquired immunity is due to the observed antibodies alone or their interplay with other immune cells. It will be important to continue to follow these healthcare workers even longer, to learn just how long their immune protection might last.

Meanwhile, more than 15 million people in the United States have now tested positive for COVID-19, leading to more than 285,000 deaths. Last week, the U.S. reported for the first time more than 200,000 new infections, with hospitalizations and deaths also on the rise.

While the new findings on reinfection come as good news to be sure, it’s important to remember that the vast majority of the 328 million Americans still remain susceptible to this life-threatening virus. So, throughout this holiday season and beyond—as we eagerly await the approval and widespread distribution of vaccines—we must all continue to do absolutely everything we can to protect ourselves, our loved ones, and our communities from COVID-19.


[1] Antibodies to SARS-CoV-2 are associated with protection against reinfection. Lumley, S.F. et al. MedRxiv. 19 November 2020.


Coronavirus (COVID) (NIH)

Combat COVID (U.S. Department of Health and Human Services, Washington, D.C.)

David Eyre (University of Oxford, England)


  • Penny Williams says:

    A question remains about the ability of the few asymptomatic, apparently reinfected patients to infect others– how does their viral shedding, if any, compare to quantities of shed infective virus among primarily-infected patients? This might bear on vaccinated naive individuals as well as on contacts of naturally-immune rare individuals who seem to have contracted the virus a second time

  • Martha says:

    I developed symptoms of Covid-19 the last week in December 2019, and began requesting antibody testing in early April. I was finally able to test in late May, and again in the second week in July. Both tests were positive, with different labs. It is almost a year later and some symptoms still continue: palpitations (which first arrived on the same day in December that I began a dry cough), some shortness of breath, fizzing, and occasional chills. I tested negative for antibodies at the end of September, and also upon donating blood via the American Red Cross on November 11. So it appears that my antibodies were present at least until seven months.

    • JC says:

      T-Cell memory likely will provide immunity, or a strong immune response up to and over a year. Studies hopefully will reveal this fact further. There is little proven evidence of Asymptomatic spread as any real factor of increasing infection rates from studies I have read.

  • Liz Urbanski Farrell says:

    Agree with the poster, Penny Williams. Reposting these findings could lead posters and readers to believe that if those who had and recovered from COVID previously continue to produce antibodies, if you had COVID it’s okay to go about your daily routine without proper COVID precautions. Until we know whether those possessing antibodies shed them and whether or not asymptomatic individuals who contract COVID could also unwittingly infect others if not masked, gloved, etc., it seems irresponsible to report this information without context.

    • rich e. says:

      How can you spread the virus when you have no symptoms it is spread by coughing and sneezing… Hello?

      • R L says:

        It is airborne and also spread by simply breathing from mouth and nose as well as talking. If it were only spread by sneezing and coughing, then the sick people would stay home and not get others sick … and well people would back away from sneezing, coughing people. The point is that people contract it and spread it before they know they are sick. Some people never develop symptoms but still are contagious as carriers.

  • Lisa Phillip Rimland says:

    We are still learning about this virus and have a lot left to go, as is apparant from reading this fascinating article. It will also be interesting to study the mechanisms and time frames of longterm immunity among vaccinated persons. But no matter what, basic preventative health measures such as the wearing of masks and social distancing must be continued.

  • John Hasty BS, MT(ASCP) Retired says:

    People infected with the whole live virus is one thing, people inoculated with a messenger RNA (mRNA) is something else.

  • Alessandro Rosa says:

    I am really circumspect about this study. I couldn’t find if they factored in things such as behavioral changes or access to better PPE at later stages of the pandemic.

    In other words, were HCWs who had already experienced COVID-19 more careful about their contacts and exposure post recovery? Did they have access to better PPE (more N95s than surgical masks, more than one mask per shift, eye protection, better engineering controls) at later points in this retrospective study, meaning that mitigation measures and not immunity were responsible for a lack of reinfection?

    • Albracht says:

      I think it is pretty clear that immunity is the primary driver in the equation. Rare cases of reinfection is almost proof positive, particularly with the recent rise in cases and deaths.

  • Elliott says:

    Do we need the vaccine if we have antibodies and if so will this be an every year dose or every six months?

  • Loretta Turon says:

    Great to hear your doing well.

  • Tom says:

    Now there is information about re-infection with coronavirus, I wonder if the antibodies have ended or perhaps it’s a new mutated virus?

    • Christine S. says:

      My father inlaw, who has been in and out of hospitals since March. Has contacted the virus now 3 times.

      • Barbara W. says:

        These test are not accurate I did rapid test on tuesdsy because I had sinus infection to rule out covid test was neg. Went to doctors following day that did another rapid was also did a PCR thurday night doctor called said I had covid! I’m waiting 3 weeks to get antibody test because I still dont believe with 2 rapid being neg and a PCR POSITIVE what should I believe?

    • John McLaughlin says:

      Will someone ANSWER my question about WEARING masks after being vaccinated?

      • Pam says:

        Wear the damn mask.

      • Jana says:

        I will always wear a mask for the rest of my life. If it ever comes to an end, gov says we can stop wearing it…. I will still wear it, in public places.

      • Doug says:

        Remember, a vaccine doesn’t prevent you from getting the virus. It helps prevent you from suffering serious illness if you DO get the virus. And if you do get the virus, you can still pass it on to others; even if you don’t feel sick.

        To paint a picture: When you’re cut open on the operating table, the surgeon is wearing a mask. The mask is not to prevent the surgeon from getting an infection from YOU. The surgeon is wearing a mask to prevent you from getting an infection from HIM. So PLEASE, continue to wear your mask after vaccination, in public places and large crowds.

      • Nick B says:

        Mask does not protect you or other from Covid

  • Don A. says:

    I had COVID and was hospitalized on April 2nd. I was in the hospital 22 days. 14 of those days on a ventilator. It was a miracle I survived. Several months later I begin donating COVID plasma at the Red Cross who tests my antibodies after each donation. I gave again last Tuesday and they reported I am still positive for antibodies. January will be my 9th month. My next donation date is January 11th.

    • JC says:

      Don, you are a hero. Thank you for donating Convalescent Plasma. I had several contacts that wanted to donate back in June and July, yet there was no infrastructure for them to provide the plasma. I hope our area has improved on this for those willing to donate. You are literally a life saver! Best wishes to you and yours.

      • Wendy says:

        I had a mild case of Covid March 16-19 2020. I got my test finally on April 12 and tested Positive on that date. Went back in May for 2nd test and tested negative. Donated blood for the first time in my life. did that 3 time and NYBC extracted my plasma. Sat 1/6 was my first plasma donation. Nothing to be scared of. I can go back on 1/23 and will continue to donate plasma as long as I can

  • Dale G. says:

    I started feeling ill around the end of November. By December12, I was definitely very sick with terrible symptoms. However, I wasn’t tested for the virus until Dec. 21; Quarantine ended Jan. 6. Strangely, I haven’t felt good since then and actually am beginning to feel sick again.

    What could be wrong????? Very discouraged.

  • Carl S. says:

    Are we talking about fatigue, shortness of breath on occasions, or nervous/anxiousness? I woke up Christmas morning about 5 am with that hangover-type headache, tickle kinda nonproductive cough, and chills. Knew I’d soon be around family went to e.r., tested positive for covid. Went home to quarantine by the end of the day all symptoms were gone. But covid highjacked my blood pressure, resulting in high readings and heart rates. Pcp almost doubled my lisinopril to accommodate. A month later and I’m stabilized as far as vitals but have a stress/ anxiousness going on which is off the charts. Still dealing with that and poor sleep since onset

    • Pam says:

      Tested covid positive then negative, and it raised my blood pressure from 120/73 to 190/105. Symptoms fatigue, low grade fever, heartburn, feel unwell.

  • John M. says:


    • Jeff K says:

      Hey John M – You should definitely continue to wear a mask, as you may still be able to infect your friends and family. Just because you are vaccinated does not mean that you cannot still acquire the virus (you just won’t feel any sick/negative effects) but you could still be a carrier.

  • M. Drake says:

    does donating plasma deplete antibodies over time or do antibodies self replicate and replenish themselves to maintain levels?

    • Alm says:

      Have shortness of breath and i have heavy congestion which does not go away, causes an ache in my back, after testing positive for antibodies.

    • Jamie Zimmerman says:

      One of my staff donates plasma twice a week at our local CSL and has had the antibodies for about 4 months. So far they’re replenishing at the same rate that her plasma does.

  • Faith says:

    Thank you to all of you that are donating plasma and blood. I am a nurse and I depend on your donations. I get plasma weekly to keep up my Immune system every injection you get , I get. I have to get everything through your donations. I’m sure that I will be one of the only nurses wearing a mask. It takes 40 donors a month is what for 1 month of treatment. I have been getting treatments for years. I am so thankful

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