Last August as the number of COVID cases wound down in the U.S. and Canada, many felt the worst was over.
After all, the numbers were falling and many were now vaccinated, especially in Canada. It was summer and regardless of their vaccination status, many were fed up with distancing and masking, especially in the U.S. and it was time to get out and have fun.
But all wasn’t as it seemed. Israel reported that two shots might not be enough because of surging breakthrough infections beginning about the three- to four-month mark following the last shot, Omicron was on no one’s radar until the late fall and there were lingering concerns about long-lasting symptoms following COVID infections.
Well, we know how Omicron turned out: steeper case number spikes than any previous wave and overwhelmed health care workers faced with cases among the unvaccinated. By now, at least the numbers appear to have peaked and are receding.
What’s not receding are the number of cases of long COVID. Some U.S. estimates suggest as many as 10 to 30 per cent of those who had COVID developed long-lasting symptoms, serious enough to limit their daily activities. Many of them had few if any symptoms at the time of the initial infection.
And adding to the total are people who have had COVID more than once based on PCR or antigen testing. Many of them were fully vaccinated and a few had received a booster shot.
Long COVID defies precise definition because of the diversity and complexity of its symptoms, which range from fatigue, weakness, various sensory symptoms, to difficulties concentrating and focusing, headaches and persistent loss of taste or smell.
In their diversity, the symptoms are similar to several other disorders such as myalgic encephalomyelitis (chronic fatigue syndrome), chronic Barr-Epstein virus infection and persistent symptoms following Lyme disease and even neurasthenia as it was described in the 19th century.
So far, investigations have not revealed any consistent biomarkers in the form of lab tests. When I first reviewed this subject in June last year, long COVID was a mystery and remains so despite the many cases who have been assessed.
Oxford University and the Imperial College in London collaboratively posted online comparative MRI and functional MRI (fMRI) studies of volunteers who a few years earlier were studied as part of the U.K. Biobank program. Some of them later developed COVID and others did not and acted as controls.
The authors posited that the SARS-CoV-2 virus gains access to the brain through the olfactory and gustatory systems, which are intimately connected to structures in the temporal lobe and elsewhere in the brain that play major roles in memory, mood and emotion, as well as smell and taste.
Their findings were striking. Abnormalities were found in many of latter regions of the brain, mostly on the left side, and more widespread in the small subgroup of patients, usually older, who were hospitalized.
For me the most important observation was the clear finding of abnormalities in the brains of COVID patients, most of whom were not hospitalized (only 15 of a total of 379 subjects). It was a marvellous study because it strongly suggests the virus reaches the brain through the olfactory system, as suspected.
Unfortunately, the study made no mention of which subjects developed symptoms and if so, what symptoms? But given the localization of the findings, it wouldn’t be too much of a stretch to suggest that some of the long COVID cognitive symptoms might be related, in part at least, to what was observed in this study, and not the imaginations of the patients.
The hypothesis that lesions in the brain might be far more common than we thought and possibly related to long COVID symptoms is worth further study but needs a bevy of psychological and other tests to complement the imaging studies and that would only be the beginning.
Still, the original study was an excellent start, but given the prevalence and duration of long COVID symptoms, the challenges of COVID will be with us for a long time as an editorial in the New England Journal of Medicine suggested last August.
That’s something we’re just beginning to realize.
Dr. William Brown is a professor of neurology at McMaster University and co-founder of the InfoHealth series at the Niagara-on-the-Lake Public Library.