COVID-19 vaccines fail to alter neuro symptoms of Long COVID

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While COVID-19 vaccination decreases the severity of COVID-19 disease and the rate of hospitalisation and death, a study published recently has found that vaccination prior to SARS-CoV-2 infection does not necessarily reduce the neurological manifestations and burden of Long COVID. This includes patients who had a severe infection that necessitated hospitalisation and those with a mild infection who did not require hospitalisation. Common neurological symptoms of Long COVID include brain fog, numbness and tingling, headache, dizziness, problems with smell and taste, and intense fatigue.

At the beginning of the study, the authors hypothesised that since COVID-19 vaccines reduce the severity of COVID-19 disease, the vaccines may also similarly reduce the neurological manifestations of subsequent Long COVID. But the findings of the study have thrown a surprise. “While vaccination decreases the severity of acute COVID-19 and the rate of hospitalisation and death, the sobering conclusion of our study is that vaccination prior to infection did not alter the subsequent neurologic manifestations of Long COVID in our clinic population,” the authors write. The study was published in the journal Brain Communications.

“We aimed to identify what effects — if any — vaccination prior to infection has on neurological symptoms of Long COVID, as well as the quality of life and cognitive function of our patients. These findings are sobering since it shows that vaccination prior to infection does not reduce the neurological manifestations of Long COVID,” Igor Koralnik from Northwestern Medicine and the corresponding author of the paper said in a release.

The study recruited the first 1,300 patients with neurological symptoms of Long COVID at the Northwestern Medicine Neuro COVID-19 Clinic between May 2020 and March 2023. Of the 1,300 participants enrolled in the study, 200 participants had been previously hospitalised for severe COVID-19, while the remaining 1,100 participants had only mild COVID-19 symptoms that did require hospitalisation.

Besides grouping the patients based on severity of the disease requiring hospitalisation, the authors also looked at the timing of infection — breakthrough infection post-vaccination and infection prior to vaccination. Based on the quantitative metrics used to assess quality of life, the study found that patients in both groups — those with severe disease requiring hospitalisation and those with a mild disease not requiring hospitalisation — had impaired quality-of-life in cognitive, fatigue, sleep, anxiety and depression immaterial of whether the infection had occurred post vaccination (breakthrough infection) or before vaccination. The study also found that patients performed worse on a range of cognitive tests compared to the general population with no difference whatsoever based on their vaccination status at the time of infection.

The study found that patients in both groups — severe disease requiring hospitalisation and mild disease not requiring hospitalisation — with breakthrough infections had more frequent pre-existing depression/anxiety than their respective pre-vaccination infection groups. Also, patients with mild disease not requiring hospitalisation due to breakthrough infections had more frequent comorbidities of headache, lung and gastrointestinal diseases than those with infection prior to vaccination. An average of 10 months after symptom onset, brain fog (86.5%), numbness/tingling (56.5%) and headache (56.5%) were the three most common neurological symptoms in patients with severe disease requiring hospitalisation. For patients with mild disease not requiring hospitalisation, the three most common neurological symptoms were brain fog (83.9%), headache (70.9%) and dizziness (53.8%). Patients with mild disease caused by breakthrough infections more frequently reported dizziness (61.5%) compared to pre-vaccination infection patients (50.6%).

The study found that patients developing neurological symptoms of Long COVID after breakthrough infections have a higher burden of comorbidities than those with pre-vaccination infection. According to the authors, this highlights different risk factors warranting targeted management. Further longitudinal studies are warranted to determine the long-term outcome of neurological symptoms of Long COVID patients with breakthrough infections and pre-vaccination infections, they note.

In another paper published in the journal Annals of Neurology in November 2024, the same team from Northwestern Medicine found that neurologic manifestations of Long COVID disproportionately affected young and middle‐age adults regardless of acute COVID-19 severity. The study found that younger and middle-age individuals accounted for 142 of 200 (71%) patients who were previously hospitalised for severe COVID-19 and 995 of 1100 (90.5%) of patients with only mild COVID-19 symptoms that did require hospitalisation.

While there was higher prevalence of comorbidities and abnormal neurologic findings in older patients, at 10 months from COVID-19 onset, there was significant lower prevalence of neurologic manifestations of Long COVID in older patients. On the other hand, younger and middle-age patients suffer from a higher burden of neurological symptoms of Long Covid and cognitive dysfunction contributing to decreased quality of life. “Neuro Long COVID principally affects adults in their prime, contributing to profound public health and socioeconomic impacts warranting dedicated resources for prevention, diagnosis and interventions,” they write.