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Breakthrough Infections in Vaccinated People Less Likely to Cause ‘Long COVID’

Posted on by Dr. Francis Collins

Long Covid. Two syringes in an arrow pointed down. symptoms of long covid in the background

There’s no question that vaccines are making a tremendous difference in protecting individuals and whole communities against infection and severe illness from SARS-CoV-2, the coronavirus that causes COVID-19. And now, there’s yet another reason to get the vaccine: in the event of a breakthrough infection, people who are fully vaccinated also are substantially less likely to develop Long COVID Syndrome, which causes brain fog, muscle pain, fatigue, and a constellation of other debilitating symptoms that can last for months after recovery from an initial infection.

These important findings published in The Lancet Infectious Diseases are the latest from the COVID Symptom Study [1]. This study allows everyday citizens in the United Kingdom to download a smartphone app and self-report data on their infection, symptoms, and vaccination status over a long period of time.

Previously, the study found that 1 in 20 people in the U.K. who got COVID-19 battled Long COVID symptoms for eight weeks or more. But this work was done before vaccines were widely available. What about the risk among those who got COVID-19 for the first time as a breakthrough infection after receiving a double dose of any of the three COVID-19 vaccines (Pfizer, Moderna, AstraZeneca) authorized for use in the U.K.?

To answer that question, Claire Steves, King’s College, London, and colleagues looked to frequent users of the COVID Symptom Study app on their smartphones. In its new work, Steves’ team was interested in analyzing data submitted by folks who’d logged their symptoms, test results, and vaccination status between December 9, 2020, and July 4, 2021. The team found there were more than 1.2 million adults who’d received a first dose of vaccine and nearly 1 million who were fully vaccinated during this period.

The data show that only 0.2 percent of those who were fully vaccinated later tested positive for COVID-19. While accounting for differences in age, sex, and other risk factors, the researchers found that fully vaccinated individuals who developed breakthrough infections were about half (49 percent) as likely as unvaccinated people to report symptoms of Long COVID Syndrome lasting at least four weeks after infection.

The most common symptoms were similar in vaccinated and unvaccinated adults with COVID-19, and included loss of smell, cough, fever, headaches, and fatigue. However, all of these symptoms were milder and less frequently reported among the vaccinated as compared to the unvaccinated.

Vaccinated people who became infected were also more likely than the unvaccinated to be asymptomatic. And, if they did develop symptoms, they were half as likely to report multiple symptoms in the first week of illness. Another vaccination benefit was that people with a breakthrough infection were about a third as likely to report any severe symptoms. They also were more than 70 percent less likely to require hospitalization.

We still have a lot to learn about Long COVID, and, to get the answers, NIH has launched the RECOVER Initiative. The initiative will study tens of thousands of COVID-19 survivors to understand why many individuals don’t recover as quickly as expected, and what might be the cause, prevention, and treatment for Long COVID.

In the meantime, these latest findings offer the encouraging news that help is already here in the form of vaccines, which provide a very effective way to protect against COVID-19 and greatly reduce the odds of Long COVID if you do get sick. So, if you haven’t done so already, make a plan to protect your own health and help end this pandemic by getting yourself fully vaccinated. Vaccines are free and available near to you—just go to or text your zip code to 438829.


[1] Risk factors and disease profile of post-vaccination SARS-CoV-2 infection in UK users of the COVID Symptom Study app: a prospective, community-based, nested, case-control study. Antonelli M, Penfold RS, Merino J, Sudre CH, Molteni E, Berry S, Canas LS, Graham MS, Klaser K, Modat M, Murray B, Kerfoot E, Chen L, Deng J, Österdahl MF, Cheetham NJ, Drew DA, Nguyen LH, Pujol JC, Hu C, Selvachandran S, Polidori L, May A, Wolf J, Chan AT, Hammers A, Duncan EL, Spector TD, Ourselin S, Steves CJ. Lancet Infect Dis. 2021 Sep 1:S1473-3099(21)00460-6.


COVID-19 Research (NIH)

Claire Steves (King’s College London, United Kingdom)

COVID Symptom Study


  • Brigit B. says:

    I was fully vaccinated with Pfizer by February 1 being in the medical field. I contracted a breakthrough case Aug 26 and made it through without hospitalization. So incredibly thankful for vaccine but now enduring debilitating fatigue and shortness of breath. Have not been able to work in almost three weeks. I’m frustrated, sad and concerned. I know this vaccine saved me but now what? I’m still suffering. This delta is brutal. Please get vaccinated it saves lives.

    • Crystal says:

      I’m 50, and believe I caught the Delta in August from my breakthrough vaccinated neighbor. I am not vaccinated. I was sick for 9 days but did not have to go to the hospital or the doctor and no medication but Excedrine and all my vitamins in extra doses. I still can’t smell 100% and I breath harder than I use to when climbing stairs but that is it! My whole family had it including my house keeper. We ALL did the same thing and recovered the same! We are all good now! No vaccines needed here, for any of us, including my parents who are 76 and 78! High vitamin D3 is the key!

      • Allison M. says:

        I’m similar like Crystal. I’m 53. had covid in March 2020, flu symptoms for 3 days, recovered at home with rest, fluids, and vitamins. Then I tested positive for covid on Sept 1 2021, had mild flu symptoms for a few hours only on each of 2 days. I didn’t even miss any work since I was fortunate to be able to work remotely from home. My kids and friends that I was in close contact with during the 5 days pre and post positive test, did not get it and are all still fine. I live in FL and try to get 10 minutes of sunshine daily, take vitamins and avoid packaged (factory) foods. Coincidentally, the 5 other people I know that tested positive in the month of August all took the mRNA covid vaccine. One got walking pneumonia. Another one went to the hospital.

  • George says:

    Thank you for this encouraging news. What is the percentage of unvaccinated individuals who develop symptoms of long Covid? This would give context to the statement that the fully vaccinated who develop symptoms are 49% as likely as the unvaccinated to report symptoms of long covid.

    • Janelle Craig says:

      See paragraph 3 above. Long covid affects 20% of the unvaccinated who contracted covid.

    • Francie Halderman says:

      George, the third paragraph above says 1 in 20, or 5% (not 20%).

    • Ashley says:

      Please, please, please get vaccinated and protect yourself. You do not want to live with long Covid…even mild long Covid. Take it from a formerly healthy 35-year female old who contracted a mild case of the virus in March 2020 and spent July – October stuck in bed in excruciating pain, unable to walk at times, I struggle to breathe or doing any kind of light lifting will take the wind out of me. I was so severely nauseous and dizzy that I could hardly get out of bed to go to the bathroom, other times I’d sleep on the bathroom floor so I wouldn’t have to get up and walk back to the bathroom again. I suffer from brain fog, forgetfulness, difficulty finding words, concentration issues, and thanks to all these symptoms I have difficulty at work now. I had the Moderna vaccine in March and it helped alleviate some of my more severe symptoms, but every day there’s something. Not to mention the atrocious medical bills. Although now I am no longer as sick as I was, I still struggle daily. I was very healthy with no preexisting conditions prior to this. I can barely go for a walk these days without being completely wiped out.
      So, some unsolicited advice from a stranger who’s living it…please save yourself and those around you, if you can, and get yourself vaccinated (with Moderna if possible). Maybe you’ll get lucky and have an experience like Crystal in the comments section above who claims she and her family were fine without the vaccine (who knows if they’ll have long Covid). Or you won’t, and instead end up in the hospital or like me and millions of others fighting off symptoms of a virus that’s no longer in your system. It is so not worth it.

      • ML says:

        . . . Almost everyone I know who caught Covid (up to a year ago) are still suffering some types of health damage – from mild annoyances to very severe problems (brain, heart, kidneys). Anything people write to minimize the effects of this virus is harmful to everyone.

  • Steve White says:

    The article says SARS CoV2 is the virus which causes Covid 19. This brings up a question I have – why are we calling the illness by a different term than the virus?
    Thank you for any information you can give.

    • Roth says:

      I think so you can talk about the virus as separate from the illness, as they are not the same thing? For example, the virus enters the body but the covid 19 is the response (illness). A virus has a shape a form and a variety of qualities and variants (i’m not a scientist so don’t have the right language) and the illness is the impact of that virus in the body. So, the illness can also look many different ways (all the different symptoms like loss of smell, brain fog, coughing etc). Also, you can be explosed to the virus but not get covid 19. Right?

  • A.L. says:

    The design of this blog is lovely, but unfortunately either the text color or the thinness of font makes it very difficult for older people and people with low vision to read. There is just not enough contrast between the text and the white background. Zooming in only helps so much.
    Guessing many of your readers are older. Please consider changing. Thanks.

  • Terry Korzan says:

    Thank you for this information. It certainly provides additional sound reasons to be vaccinated. I’m just curious about the statement “people with a breakthrough infection were about a third as likely to report any severe symptoms”. Were the study authors able to determine, from their data, if there were significant differences in which vaccine was most protective against severe symptoms in breakthrough infections? Thank you!

  • Paul says:

    Drawing such concrete conclusions from a study on a non-representative population (self selecting people who chose to use an app to report their symptoms) is absurd and violates basic principles of research. I await studies with a more representative sample: people who do not report their symptoms on an app.

    • D Rae says:

      Amen to Paul’s comment! I thought the same thing! In my google search: “studies completed by the NIH”, the first study that comes up is this? The study was completed in the United Kingdom with “self-selecting people” using an app.? It’s preposterous! It’s NOT a study without a representative population!

  • Eileen Natuzzi says:

    I would like to see more recent delta driven data. This data predating the delta domination could be underestimating the risk of long covid in vaccinated individuals.
    Also I would like to see some research data on the “long covid-like” symptoms people who got the vaccine have suffered (paraesthesias, tinnitus, fatigue, brain fog). Who, why and how need looking into so we can tailor risk.

  • Nancy Petkovic says:

    So who’s to get a third covid injection or is that still advisable at this point? Also, why the vaccinated are experiencing breakthrough covid…could it be a possible ” bad batch” of vaccines, not given properly i.e at the right temperature or is it just the way it is like getting the flu when one gets an annual flu vaccine? I’m stumped.

  • Diana heichel says:

    I was fully vaccinated in February ( both shots). 8-06-21 I developed symptoms of COVID diagnosed positive 8-12 and am still coughing, very fatigued and muscle pain which is debilitating. It is now 9-14 . Never hospitalized and I also had an infusion of antibodies.

  • Tracey Brown says:

    How does genetics play into the covid impact? Both My son 26 and my other son 13 got Covid, were not vaccinated and had very mild symptoms, however a carpenter I know in early forties and an Inlaw in late forties were both hospitalized and still recovering , thank god. None of them were vaccinated. My Wife and I were vaccinated early in the program and we checked to see if we were carriers during our 13 year old’s case and we were not, even though we were in very close contact with our youngest son before diagnosis and during his quarantine from school.

  • ALEJANDRA T. says:

    My husband and I both fully vaccinated with Pfizer, we both got Covid in August, no hospitalization, but had fever for 3 days, cough and body aches.
    After Covid, my husband continue with cough. I experienced swollen glands under my armpit and breast, trouble focusing and my head feels heavy in the morning lasting a few hours.

  • Karen R says:

    I was vaccinated 4/1/2021 with single dose J&J. I was diagnosed with Covid 7/23/2021. I was fortunate and had a slight case. As of today 9/14/3021 I still have a cough and an odd smell in my nose. It started out as a burning smell and now has totally changed to more of a hair dye smell. Drives me nuts.

  • Benny M. says:

    I had the J&J vaccine and still got covid.Now my blood pressure is all messed up.I had high blood pressure to start with but now it is high and low

  • Lee S. says:

    I got Covid the week of Feb.13, 2020 before vaccines were available. I have two autoimmune diseases so I am super careful and have still not been out except to Dr’s. since Feb. 2020. My Covid turned into long Covid, and I’ve been sick with fevers, pain and worsening of lung problems. I can’t get vaccinated because I’m too sick to go out plus it’s not advisable for anyone with a fever and all the other health problems I have. My immediate family did get fully vaccinated in hopes to protect themselves and me. We All mask ALL the time! Recently they all got mild break through cases, more annoying than sick. I still have my same old fever, pain and chest and lung symptoms, but nothing like the probable Delta they have. We think my antibodies from the long Covid is protecting me, or the fact I don’t go out in public and I even mask at home!

    • Brian G. says:

      Same thing with me. I hope the NIH is seeing this. That first weekend of Feb. 2020, the Covid wasn’t hardly announced as being here. That same weekend was after my granddaughter sent home from school early with fever. Okay, but she’s 3 feet next to me drawing, coloring and sneezing every 5-6 seconds profusely. I said bless you so many times my throat got hoarse. 3 days later the trouble started! Whole household throwing up, mount vesuvius, body aches, metallic taste in mouth, every joint, bone and muscle in body seering in pain, breathing problems. I didn’t know what it was as the covid wasn’t explained yet. I got over it after a few days, but have long covid today. 2 years later. 15 hours a day in bed, brain fog, nerve problems, breathing and voice problems. I wasn’t eligible for vaccine until 15 months later, and that helped with a couple things like the multiple daily heart attacks and dozens daily mini-strokes. I hope the NIH can please help us with this ’cause it’s only getting worse daily and I don’t know how much more I’ll live. I’m only 61 yrs. old. Good luck with yous and know that you’re not the only one!

  • Simone says:

    Last January I had terrible body aches to the point that I walked with great difficulty. I thought I had arthritis as I am 76 years old. Finally I survived and continued going to work. Believe it or not, I am a teacher. in March I had the first moderns vaccine and I felt the same pains I had in January. 3 days later I had a serology test that revealed I had been infected by Covid earlier. I kept on working ..and got the second shot in May. I have suffered no Covid lasting effect. I am in good health. No high blood pressure, no cholesterol , diabetic, etc… Is this due to the fact I am Mediterranean and always eating a Mediterranean diet? Raw garlic, lemon juice, olive oil, fruits, etc….

  • Brenda S. says:

    My twin sister is 53 and has been in the hospital for over 3 weeks. She is unvaccinated. She is also a diabetic. How does the vaccine help people that are vaccinated and with diabetes if they contract covid? I am also a diabetic

  • DR. SAUMYA PANDEY, PH.D. says:

    Innovative Long Covid-19 syndrome epidemiology clinical research study with critical research insights in asymptomatic vs symptomatic vaccinaed vs unvaccinated populattion-subsets of varying genetic ethnicities!

  • James says:

    I know several people who have contracted COVID and are vaccinated. They all very little or ZERO reaction to their vaccines. Is there any correlation to those who do not have a very mellow reaction to the vaccine and breakthrough cases?

    • Brigit says:

      I was fully vaccinated and had a breakthrough case. I did have a lot of symptoms from vaccines. After had an antibody test and had tons of antibodies. Got last shot feb 1. Lots of antibodies feb 11. Got breakthrough on Aug 26.

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