Does vaccination prevent long COVID?

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In a recent study published on the Preprints with The Lancet* server, researchers from France and the United States evaluate the effect of coronavirus disease 2019 (COVID-19) vaccination on a large ongoing prospective cohort of patients with long COVID. To this end, the researchers observed that vaccination lowers the intensity and life impact of long COVID among patients with persistent symptoms.

Study: Efficacy of COVID-19 vaccination on the symptoms of patients with long COVID: a target trial emulation using data from the ComPaRe e-cohort in France. Image Credit: Blue Planet Studio /

*Important notice: Preprints with The Lancet publishes preliminary scientific reports that are not peer-reviewed and, therefore, should not be regarded as conclusive, guide clinical practice/health-related behavior, or treated as established information.

What is long COVID?

‘Long COVID’ refers to the persistence of COVID-19 symptoms for several weeks to months after the affected patient has recovered from infection with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). According to the United Kingdom Office for National Statistics, around one in 10 people who have been infected with SARS-CoV-2 experience long COVID (or post-acute COVID) for several months after the onset of infection.

Studies suggest that persistent symptoms could be a result of organ dysfunction following the acute phase of the disease, post-traumatic stress linked to the disease, or viral persistence.

Notably, 90% of patients with long COVID still report symptoms after nine months of onset. Furthermore, 67% of these patients with long COVID have not been able to return to previous levels of work.

To date, there is no standard of care for people suffering from long COVID. Some researchers have suggested that COVID-19 vaccination might improve patients’ condition by eliminating potential viral reservoirs; however, only sparse evidence currently supports this hypothesis.

About the study

In the current study, the researchers utilized data from the Community of Patients for Research (ComPaRe) long COVID cohort, which is a nationwide e-cohort of long COVID patients underway in France. The primary goal of this cohort is to emulate a trial evaluating the effect of the first COVID-19 vaccine injection among patients with long COVID on the severity and overall disease impact on their lives.

Patients who self-reported a confirmed or suspected COVID-19 infection with symptoms lingering for more than three weeks past the initial onset were included in the cohort. A total of 910 adult patients (≥ 18 years old) were included in the study, of which 455 patients were allocated to the vaccination group and 455 to the control group.

The study encompassed three observation points, which included T0: cohort enrollment/baseline, T1 (day 60), and T2 (day 120). At each observation, patients were inquired if they still had symptoms related to COVID-19.

Those reporting persisting symptoms were asked to fill the COVID symptom tool (ST) and impact tool (IT), as well as complete questionnaires assessing 53 long COVID symptoms and 6 dimensions of patients’ lives that can be impacted by the disease.

The long COVID ST score can range from 0, which indicates disease remission, to 53. Similarly, long covid IT score ranges from 0, thus signifying no impact, to 60, which indicates maximal impact.

The long COVID IT score was analyzed after dichotomization according to its Patient Acceptable Symptom State (PASS), which represents the score below which 75% of patients considered their symptom state acceptable.

Study findings

At the T2 observation point or day 120 from baseline, long COVID symptoms were significantly less severe in the vaccination group as compared to the control group. The mean long COVID ST score was 13 in the vaccination group and 14.8 in the control group.

By T2 point, 16.6% of patients in the vaccination group reported a remission of all symptoms from long COVID, which was compared with 7.5% in the control group.

The impact of long COVID on patients’ lives was significantly lower in the vaccination group than in the control group. The mean long COVID IT score was 24.3 in the vaccination group and 27.6 in the control group.

The proportion of patients reporting an unacceptable symptom state (PASS) was 38.9% in the vaccination group and 46.4% in the control group.

Study implications

“Vaccination leads to an improvement in symptoms among patients with long COVID. These results support the hypothesis that, for at least some patients with long COVID, the disease is mediated by a persistent viral reservoir and/or by circulating virus fragments.”

The proportion of patients reporting an acceptable symptom state also increased by 7.5%, thereby implying that for every 13 long COVID patients who underwent vaccination, one will experience a notably reduced disease impact on his/her life.

“Our results show that vaccination doubled the remission rate of long COVID symptoms.”

The study also confirms the safety of vaccination for patients with long COVID, with only two (0.4%) patients reporting an adverse effect that required hospitalization.

From a public health perspective, these results are critical in times of vaccine hesitancy, especially among patients who have had a SARS-CoV-2 infection and may fear relapse or worsening in symptoms.

Limitation of the study

All patients in the current study were infected before May 1, 2021, and thus were not infected with recent SARS-CoV-2 variants of concern, such as the Delta variant. The vaccine efficacy on persistent symptoms occurring after infection with these variants thus remains unknown.

*Important notice: Preprints with The Lancet publishes preliminary scientific reports that are not peer-reviewed and, therefore, should not be regarded as conclusive, guide clinical practice/health-related behavior, or treated as established information.

Journal reference:
Namita Mitra

Written by

Namita Mitra

After earning a bachelor’s degree in Veterinary Sciences and Animal Health  (BVSc) in 2013, Namita went on to pursue a Master of Veterinary Microbiology from GADVASU, India. Her Master’s research on the molecular and histopathological diagnosis of avian oncogenic viruses in poultry brought her two national awards. In 2013, she was conferred a doctoral degree in Animal Biotechnology that concluded with her research findings on expression profiling of apoptosis-associated genes in canine mammary tumors. Right after her graduation, Namita worked as Assistant Professor of Animal Biotechnology and taught the courses of Animal Cell Culture, Animal Genetic Engineering, and Molecular Immunology.


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