The long COVID even with Omicron

You have an 8% chance of developing the condition if you are vaccinated, according to new data

Posted May 8

Vincent Brousseau-Pouliot

Vincent Brousseau-Pouliot
The Press

What is the probability of developing a long-lasting COVID of at least one month? 7% to 9% in adequately vaccinated people, according to UK government data released on Friday.

These early data on long COVID with the Omicron variant confirm that: 1) the vaccine greatly reduces (by half, according to UK Public Health) the risk of developing long COVID; 2) the less virulent Omicron variant is half as likely to cause long COVID as previous variants.

Before the vaccine, approximately 40% of non-hospitalized patients who caught COVID-19 (original strain of coronavirus, Alpha, Delta variants) developed long-lasting COVID for at least three months, and 46% of non-hospitalized patients, long-lasting COVID of at least one month, according to a Quebec study carried out before the vaccination campaign⁠1.

But the vaccine greatly reduces the chances of having a long COVID. As of April 3, 7% to 9% of triple-vaccinated UK adults had COVID lasting one to two months, according to data released Friday by the UK’s Office for National Statistics.⁠2 (the equivalent of Statistics Canada). The percentage (prevalence rate) varies between 7% and 9% depending on the variant responsible for the infection (Delta, Omicron BA.1, Omicron BA.2). Around 9% of UK adults with two doses of vaccine have long COVID one month after infection with Omicron BA.1.

A third dose of vaccine would roughly halve the odds of getting long COVID with Delta (the risks would drop from 15.9% to 8%), but it would not have a significant effect against long COVID with Omicron BA.1, according to UK data. (Omicron is the dominant variant in Quebec and in many countries today.)

“Among triple-vaccinated adults, we estimate that approximately one in 15 people infected with the Omicron BA.1 variant will have long-lasting COVID symptoms one month after infection. This proportion would increase to one in 12 people infected with the Omicron BA.2 variant,” says Daniel Ayoubkhani, senior statistician at the Office for National Statistics.

Some data on the long COVID

Long COVID is the disabling version of COVID, which causes one or more symptoms (fatigue, shortness of breath, cognitive impairment, headaches, muscle pain, loss of taste or smell, etc.) to last for at least a month (US definition) or at least three months (World Health Organization definition) after contracting COVID. Some patients with the most severe form of long-term COVID become downright disabled: they can no longer work or go about their activities as they are tired or physically affected.

As of April 3, around 2% of Britons had had long-lasting COVID for at least three months. It’s 1.3 million people. About 1.8 million Britons had had long-lasting COVID for at least a month (2.8% of the population), and 0.8 million for at least a year (1.2% of the population).

If we apply this rate of 2% in Quebec, approximately 138,000 Quebec adults would have experienced a long COVID of at least three months.

The Ministry of Health and Social Services of Quebec does not reveal the number of patients with long COVID.

A “very significant” effect, according to Dre Tam

Long COVID should not be taken lightly, experts warn.

“We anticipate that it will probably have a very significant effect [substantial] », dit the Dre Theresa Tam, Chief Public Health Officer of Canada. “We are still trying to understand the long COVID. » The advice of the Dre Tom? “If you don’t get COVID, you won’t get long COVID,” she says.

“We must not trivialize the long COVID, even if it was worse at the start of the pandemic when people were not vaccinated”, explains the epidemiologist Gaston De Serres, chief physician of the immunization scientific group of the National Institute of Public Health of Quebec (INSPQ).

Even with vaccines, there are patients who drag on symptoms for weeks and months.

Gaston De Serres, Chief Physician of the INSPQ Immunization Scientific Group

Not all long COVIDs are this bad. Some are unpleasant, like when you lose your sense of smell, but allow you to live relatively normally. On the other hand, patients see their lives completely turned upside down. Going for a walk can take them hours of recovery.

In the UK, 20% of patients with long-lasting COVID (at least three months) feel that it has greatly reduced their daily activities (severe form), compared to 47% of patients with a slight reduction in activities (mild form) and 33% of patients without impact on their quality of life (very mild form).

“We don’t want to sow fear, it’s not productive. But people need to be aware that the risks of developing complications with long COVID are real, even if they decrease with vaccination, new variants and the impact of new drugs. These risks are not going away, and the consequences can be severe,” says Emilia Falcone, director of the post-COVID research clinic at the Montreal Clinical Research Institute (IRCM) and infectious disease specialist at the CHUM.

Symptoms and causes

The main symptom of long COVID: fatigue, which affects 50% of patients with long COVID for at least three months in the UK. Next come, among other things, shortness of breath (34% of patients), loss of smell (31%), difficulty concentrating (25%), muscle pain (24%), loss of taste ( 24%), headache (22%), memory loss/confusion (20%), sleep disturbance (19%), cough (17%) and anxiety (17%).

Can you develop a long COVID during a reinfection with Omicron? Yes, indicates the Dre Falcone, who has seen cases at his Montreal clinic.


The Dre Emilia Falcone, Director of the IRCM’s Post-COVID Research Clinic

Scientists are still looking for the cause of the long COVID. Five major hypotheses are put forward.

  1. In some cases, particularly in patients hospitalized during their infection or with a severe infection, the inflammation during the infection leads to damage to tissues around blood vessels and in various organs, including the lungs.
  2. Virus particles could linger in the body and cause sustained inflammation.
  3. The viral infection would disrupt the immune system and it would attack the body (autoimmune disease).
  4. The virus would enter the intestine and disrupt the intestinal flora, leading to inflammation in the rest of the body.
  5. Microclots forming in the blood vessels would cause damage to various organs, including the nerves (which would explain certain neurological symptoms).

1. The Quebec study was conducted among 6061 healthcare workers between July 2020 and May 2021 (approximately 95% of study participants were unvaccinated). A study carried out by the University of Oxford before the vaccination campaign came to the same conclusion.

2. UK Long COVID data by variant and vaccination status include cases of first infections from mid-May 2021 to mid-April 2022.

Learn more

  • 6 %
    Percentage of patients with long COVID in the UK (at least three months) who were hospitalized during their COVID infection

    Source: UK Office for National Statistics

    Women aged 35 to 49
    Group of people most likely to have long COVID. Indeed, women aged 35 to 49 who already have health problems limiting their activities, who work in health, education or social services and who live in disadvantaged neighborhoods.

    Source: UK Office for National Statistics



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