There has been ongoing concern not just about becoming infected with COVID-19, but also about developing ongoing symptoms known as long COVID. While there is no precise definition of this term, it generally refers to symptoms persisting more than two months after recovering from infection.1Long COVID or Post-COVID Conditions https://www.cdc.gov/coronavirus/2019-ncov/long-term-effects/index.html#:~:text=Some%20people%20who%20have%20been,(PCC)%20or%20long%20COVID.
Indeed, early in the pandemic, studies in hospitalized patients reported ongoing symptoms more than a month after discharge in 25-80 percent of patients. Has the risk and burden of long COVID changed with the decreasing severity of disease caused by the Omicron variant?
Early on, the Wuhan and even Delta strains were associated with more severe disease and the development of COVID pneumonia and lung scarring. As well, a very frequent complaint was the loss of smell and taste which often persisted for many months after the infection cleared. MRI studies showed persisting inflammatory changes in the regions of the brain that sense smell and taste as the likely cause.
The Omicron strain, which has dominated infections since the start of this year, has been shown to be more contagious but less dangerous than previous strains. It affects the upper airways much more than the lungs and causes much less frequent disturbance of smell and taste but likely more gastrointestinal symptoms. This difference in Omicron targeting different organ systems has also led to differences in the frequency and nature of perceived ongoing symptoms.
A recent study by Antonelli and others published in the Lancet compared the risk of long COVID symptoms after one month of infection in a large U.K. population.2Risk of long COVID associated with delta versus omicron variants of SARS-CoV-2 https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(22)00941-2/fulltext They compared 56,000 people infected with Omicron between December 2021 and March 2022 to 41,000 people infected with the more dangerous Delta strain between June and November 2021. People self-reported their symptoms using a COVID symptom study app. Long COVID occurred in 4.5 percent of Omicron and in more than double, namely 10.8 percent, of Delta infected persons. Symptoms for both strains included fatigue, headaches, brain fog, anxiety, depression, palpitations, and gastrointestinal symptoms. People under 60 had a lower incidence of symptoms for both strains.
As previously demonstrated, other risk factors besides age were needed for hospitalization, and especially ICU, admission. The nature of long COVID also seems to have changed based on the organ systems affected by the virus. Also, since pneumonia is much less prevalent, persisting symptoms due to residual lung scarring are much less frequent. Some of the persisting anxiety and depression seen after infection was likely related to PTSD associated with the trauma of hospitalization, especially ICU care, and fear of impending death.
Previous vaccination greatly reduces the risk of hospitalization3COVID-19: Effectiveness and benefits of vaccination https://www.canada.ca/en/public-health/services/diseases/coronavirus-disease-covid-19/vaccines/effectiveness-benefits-vaccination.html and thus, again, it is not surprising that persons vaccinated have a lower risk of prolonged symptoms.
The presence of ongoing fatigue can be frustrating and is also seen with other viral illnesses, such as mononucleosis. The mechanism is not well understood but may be related to an inflammatory effect on the brain. While this resolves in most people, a small number develop chronic fatigue syndrome—that is, symptoms persisting beyond six months. The greatest predictor of lasting symptoms is the severity of the infection.4COVID-19: Long-term effects https://www.mayoclinic.org/diseases-conditions/coronavirus/in-depth/coronavirus-long-term-effects/art-20490351
Some viruses such as herpes, chickenpox, and West Nile are more frequently associated with encephalitis, a serious brain inflammation. The post-COVID-19 brain fog is likely a mild version of brain inflammation.5“Brain fog after COVID-19 is biologically similar to cognitive impairment caused by cancer chemotherapy, something doctors often refer to as ‘chemo brain.’ In both cases, excessive inflammation damages the same brain cells and processes, according to research led by Stanford University School of Medicine.” https://med.stanford.edu/news/all-news/2022/06/brain-fog-covid-chemo-brain.html#:~:text=Brain%20fog%20after%20COVID%2D19%20is%20biologically%20similar%20to%20cognitive,Stanford%20University%20School%20of%20Medicine. Analysis of spinal fluid may show the presence of inflammatory markers, although most MRI studies show only minor brain changes.
Many people now have much less fear of becoming infected, especially if they only suffer a relatively low-grade cold, as I did. There is greater fear of developing persisting long COVID symptoms. Fortunately, even most of these symptoms are relatively mild and resolve within a few months.
There is no treatment for long COVID. The symptoms related to persisting inflammation or trauma to organ systems need time to resolve. The best solution is to not become infected, however in the current environment most people have or will become infected at one time, and some even more than once. Vaccination remains somewhat protective against infection, and future vaccines targeted to prevent infection by newer strains should further reduce risk in the future.
The risk of long COVID has greatly decreased as the Omicron strain is less dangerous and, most importantly, few people now require hospitalization. While even people with mild disease can develop persisting symptoms, particularly mild fatigue, we need to take comfort in the reduced risk and severity of long COVID.
