Impact of Pre-Infection COVID-19 Vaccination on the Incidence and Severity of Long COVID: A Retrospective Case–Control Study, 2025, Barado et al.

SNT Gatchaman

SNT Gatchaman

Senior Member (Voting Rights)
Staff member
Impact of Pre-Infection COVID-19 Vaccination on the Incidence and Severity of Long COVID: A Retrospective Case–Control Study
Elena Barado; Silvia Carlos; Laura Moreno-Galarraga; Fares Amer; Nicolás Escrivá; María Gabriela Torres; Gabriel Reina; Alejandro Fernandez-Montero

Long COVID is an emerging condition with an important impact on the quality of life of affected individuals. This study aims to analyse the association between complete vaccination prior to SARS-CoV-2 infection and the subsequent development of long COVID, including its symptoms and their frequency through a retrospective case–control study.

Cases included participants with long COVID, while controls were participants without long COVID but who had a SARS-CoV-2 infection. Data were collected through a self-reported survey.

The study demonstrates a significant association between vaccination and a lower incidence of long COVID, adjusted for sex, age, university education, body mass index, physical activity, race, tobacco use, alcohol intake, adherence to Mediterranean diet, previous illness, flu vaccination, health care worker, high-risk COVID worker and sleep hours and sedentarism (OR 0.49, CI 95% 0.28–0.87). Furthermore, there is a statistically significant association between vaccination and reduced symptoms such as anosmia, dysgeusia, myalgia or arthralgia, as well as a lower overall number, adjusted for the aforementioned variables.

These findings suggest that the vaccine could be associated not only to a milder course of SARS-CoV-2 infection but also with an improvement in the state of long COVID and its symptoms.

Link | PDF (Immunology) [Paywall]
 
John Mac said:
I took it to mean vaccination before getting infected resulting in LC

"This study aims to analyse the association between complete vaccination prior to SARS-CoV-2 infection and the subsequent development of long COVID"
Click to expand...
In isolation, I read it as post-LC-vaccine improves LC. But as you say, the title says pre-LC-vaccine. So I’m confused!
 
Utsikt said:
In isolation, I read it as post-LC-vaccine improves LC. But as you say, the title says pre-LC-vaccine. So I’m confused!
Click to expand...
The present study consists of an open observational, retrospective case–control study, ongoing since its initiation on 17 May 2022. Controls were those participants who had experienced an acute COVID-19 infection without presenting symptoms of long COVID. Cases were participants who reported a long COVID diagnosis. Data collection was conducted through an electronic document with self-reported values, including sociodemographic, clinical and lifestyle variables
Click to expand...
The main independent variable of the study, full vaccination status prior to infection, is collected through a table with multiple-choice options for the different types of vaccines approved in Spain to date (Pfizer, Moderna, Oxford, Janssen and others or unknown) along with the option of not having received any vaccine dose. If any dose had been received, participants had to specify the number of doses, type, and date of each dose. The data were checked to ensure chronological plausibility. The dates of the doses, the interval between each dose, and that the vaccination date preceded the onset of the first COVID-19 infection was studied.
Click to expand...
 
I am not totally with it today so may be wrong but I took it to mean the study showed that prior vaccination both reduced the likelihood of developing Long Covid and reduced the severity of any Long Covid that developed. However I am not sure how the study design could demonstrate.
 
Conclusion said:
In this study, complete vaccination prior to acute COVID-19 infection is associated with a reduction in the risk of developing long COVID in the multivariate analysis. Within the population affected by long COVID, complete vaccination before acute infection is associated with a reduction in long COVID symptoms and a reduced overall symptom count.
Click to expand...
 
Utsikt said:
In isolation, I read it as post-LC-vaccine improves LC. But as you say, the title says pre-LC-vaccine. So I’m confused!
Click to expand...
It's a reasonable conclusion to draw, given the way they phrased it. I think it's rather misleading although probably not intentionally so.

Long Covid is a very loose entity. If people are getting milder Covid-19 infections, then it's not surprising that some are not getting the persistent symptoms that result from severe illnesses. It's still possible that vaccination is not protective against LC ME/CFS.

It's also possible that there is some other protective factor associated with 'people who get vaccinated' rather than the vaccination itself that wasn't accounted for. People who get vaccinated might be more conscientious and so take better care of their health, more likely to have employers who give them time off when they get sick, more likely to have people who care about them enough to both arrange vaccinations and nurse them when they are sick. On that last point, we so often see Spanish studies that report all the details of their cohorts personal lives - married, single, divorced, widowed or whatever, so it's a bit strange that they didn't adjust for having a 'significant other'.

Nevertheless, from the abstract, getting vaccinated looks to lower the odds of subsequent persistent symptoms by a lot
abstract said:
The study demonstrates a significant association between vaccination and a lower incidence of long COVID...(OR 0.49, CI 95% 0.28–0.87)
Click to expand...
 
An issue I don’t know how could be accounted for is that someone who is vaccinated may be less likely to say their symptoms are related to a covid infection. After all they are vaccinated and so «safe» from harms from covid.
 
Midnattsol said:
An issue I don’t know how could be accounted for is that someone who is vaccinated may be less likely to say their symptoms are related to a covid infection. After all they are vaccinated and so «safe» from harms from covid.
Click to expand...

On the other hand, there are people who don't get vaccinated because they don't believe Covid is dangerous (for people like themselves), so if they go on to have LC-type symptoms they'll be less likely to attribute them to Covid.
 
You must log in or register to reply here.
Back
Top Bottom