Many public health officials have taken heart from early evidence suggesting that infections from the Omicron variant cause less serious illness than other versions of the coronavirus. But another important question looms: whether infection with Omicron, including breakthrough cases in vaccinated people, can lead to long-term Covid – the constellation of physical, neurological and cognitive symptoms that can last for months and harm people’s everyday lives.
It is too early for scientists to know much about the relationship between Omicron, vaccination and long-term Covid. Research from earlier in the pandemic does not provide definitive clues. Here’s an outline of what scientists have learned and the many questions that remain to be answered.
Can Omicron Cause Long-Term Covid?
Since the Omicron variant was first identified in late November, it’s too early to say how long the symptoms of infection may last. It’s also unclear whether, like previous versions of the virus, it can lead to the development of problems such as brain fog or extreme fatigue after the infection has cleared.
While recent reports suggest that Omicron may cause less severe initial illness than other variants, the basic symptoms of infection with Omicron are similar to infection with other variants, suggesting that long-term effects may also be similar.
Milder initial illnesses don’t necessarily mean Omicron is less likely to lead to long-term Covid, doctors, researchers and patient-led groups caution. Studies of previous waves of the pandemic indicate that many people who had mild or asymptomatic first reactions to a coronavirus infection developed Covid for a long time that lasted for months.
Can Vaccines Prevent Long-Term Covid?
Vaccines mainly prevent people from becoming seriously ill or dying from an infection with the corona virus. With some previous variants, vaccines seemed to reduce the chance of infection themselves – and not getting infected is, of course, the best way to avoid long-term Covid. But vaccines have not been as effective at preventing infection with Omicron, and breakthrough infections with this new variant are much more common.
Studies on vaccinated people and long-term Covid have so far focused mainly on data collected before the emergence of the Delta variant. And the research results are mixed.
A large study, published in the journal The Lancet Infectious Diseases, was based on reports to a phone app by more than 1.2 million British adults who received at least one dose of a coronavirus vaccine between December 2020 and July 2021. found that people who had received two doses of vaccine and developed breakthrough infections were about half as likely as people who had not been vaccinated to report symptoms that persisted for at least 28 days after their infection. About 5 percent of those with breakthrough infections reported such persistent symptoms, the study found, compared with 11 percent of infected people in an unvaccinated control group.
Another large study, which was published without peer review, found an equally encouraging result. The study, conducted by Arcadia, a healthcare data company, and the Covid Patient Recovery Alliance, a collaboration of leaders with public and private sector health expertise, analyzed the data of approximately 240,000 patients infected with the coronavirus by May 2021. .
It found that people who received even one dose of a Covid vaccine before their infection were seven to 10 times less likely to report two or more symptoms of long-term Covid 12 to 20 weeks later. The study, which was led by Michael Simon, Arcadia’s director of data science, and Dr. Richard Parker, the company’s chief medical officer, also found that people who received their first vaccine dose after contracting the coronavirus were less likely to develop long-term Covid than those who remained unvaccinated, and the sooner they were vaccinated after infection. , the lower the risk of long-term symptoms.
But the results of another study, also not yet peer-reviewed, were more discouraging about vaccines’ ability to prevent long-term Covid. The study was conducted by researchers in the United Kingdom who analyzed electronic health records of patients in the United States. It compared about 10,000 people who had received Covid vaccines with a similar number of people who had not been vaccinated against the coronavirus but had a flu vaccine – an attempt to limit the number of people in the study who could be considered hesitant or who had generally less healthy behaviors, the researcher said.
The study found that having a coronavirus vaccine before being infected did not reduce the risk of most symptoms of long-term Covid. There was some suggestion from the data that vaccinated people may have a lower risk of long-term problems such as abnormal breathing and cognitive symptoms, the authors wrote, but those results were not statistically conclusive.
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The authors said it was possible that because their data was based on electronic health records, the study may have captured only patients with the most severe symptoms, rather than a larger number of patients who did not seek medical attention for their symptoms.
Can Vaccines Help If You Have Covid For A Long Time?
When vaccines were first rolled out, before the emergence of the more contagious Delta variant that predated the even more contagious Omicron variant, some patients with long-term Covid found that symptoms such as brain fog, joint pain, shortness of breath and fatigue improved after being vaccinated. . Still, many people experienced no difference in symptoms after vaccination and a small percentage said they felt worse.
A study by the Office for National Statistics in the United Kingdom found that in people aged 18 to 69 who reported their symptoms between February and September 2021, a first dose of a vaccine increased the chance of reporting long-term Covid symptoms by 13. percent decreased. A second dose further reduced the chance by 9 percent, the study found.
Some researchers say it could make scientific sense that vaccines could help some people with long-term Covid.
The cause of long-term Covid is still unclear and different symptoms may have different underlying causes in different patients, experts say. Some leading theories are that the condition may be related to remnants of the virus or its genetic material that linger after the initial infection has cleared, or to inflammation or circulatory problems caused by an overactive immune response that can’t be turned off.
Akiko Iwasaki, an immunologist at Yale, has said vaccines can provide lasting relief in people whose symptoms are caused by remnants of the virus if the antibodies generated by the vaccines eliminate those remnants. But in people whose symptoms may be caused by a post-viral reaction similar to an autoimmune disease, she said, vaccines may only help temporarily, and problems such as fatigue may resurface.