Covid-19 vaccine effectiveness against post-covid-19 condition among 589 722 individuals in Sweden: population based cohort study, 2023, Lundberg-Morr

Covid-19 vaccine effectiveness against post-covid-19 condition among 589 722 individuals in Sweden: population based cohort study
Lisa Lundberg-Morris; Susannah Leach; Yiyi Xu; Jari Martikainen; Ailiana Santosa; Magnus Gisslén; Huiqi Li; Fredrik Nyberg; Maria Bygdell

Objectives
To investigate the effectiveness of primary covid-19 vaccination (first two doses and first booster dose within the recommended schedule) against post-covid-19 condition (PCC).

Design
Population based cohort study.

Setting
Swedish Covid-19 Investigation for Future Insights—a Population Epidemiology Approach using Register Linkage (SCIFI-PEARL) project, a register based cohort study in Sweden.

Participants
All adults (≥18 years) with covid-19 first registered between 27 December 2020 and 9 February 2022 (n=589 722) in the two largest regions of Sweden. Individuals were followed from a first infection until death, emigration, vaccination, reinfection, a PCC diagnosis (ICD-10 diagnosis code U09.9), or end of follow-up (30 November 2022), whichever came first. Individuals who had received at least one dose of a covid-19 vaccine before infection were considered vaccinated.

Main outcome measure
The primary outcome was a clinical diagnosis of PCC. Vaccine effectiveness against PCC was estimated using Cox regressions adjusted for age, sex, comorbidities (diabetes and cardiovascular, respiratory, and psychiatric disease), number of healthcare contacts during 2019, socioeconomic factors, and dominant virus variant at time of infection.

Results
Of 299 692 vaccinated individuals with covid-19, 1201 (0.4%) had a diagnosis of PCC during follow-up, compared with 4118 (1.4%) of 290 030 unvaccinated individuals. Covid-19 vaccination with any number of doses before infection was associated with a reduced risk of PCC (adjusted hazard ratio 0.42, 95% confidence interval 0.38 to 0.46), with a vaccine effectiveness of 58%. Of the vaccinated individuals, 21 111 received one dose only, 205 650 received two doses, and 72 931 received three or more doses. Vaccine effectiveness against PCC for one dose, two doses, and three or more doses was 21%, 59%, and 73%, respectively.

Conclusions
The results of this study suggest a strong association between covid-19 vaccination before infection and reduced risk of receiving a diagnosis of PCC. The findings highlight the importance of primary vaccination against covid-19 to reduce the population burden of PCC.


Link | PDF (BMJ)

 

The key quote for me is the following

I'd still have to deep dive into the data, but I wouldn't be surprised if the only things reduced are related to a worse acute infection even hospitalisation or respiratory/cardiological damage due to an acute infection, rather than anything related to a multsystemic long-lasting Long Covid that often resembles ME/CFS or anything related to neurocognitive Long Covid or other phenotypes of Long Covid that are less self-resolving.

The following data is also of particular relevance:
8.2% of the non-vaccinated patients were hospitalised vs only 1.3% of the vaccinated cohort. So you'll have a bunch of things that might be primarily driven by a severe acute infection (we know Paxlovid is excellent at preventing this, but that isn't the point of the study). Furthermore they are comparing alpha in the unvaccinated cohort vs omicron in the vaccinated cohort.

Are they studying Long Covid or are they studying PICS? Do they even know?

It might be interesting to correct this data, w.r.t. to long-term progression as well as hospitalized patients, but I expect by the time you've done that you'll be quite dissapointed in the results...

 

The difference could also be lower rates of LC from Omicron versus pre-Omicron variants (the vaccinated cohort, on the right, was 75% Omicron, while the unvaccinated cohort was 88% pre-Omicron). That's definitely something we've seen in other studies.

 

They do actually report vaccine effectiveness by variant (Pre-alpha/Alpha, Delta, Omicron):

41% vaccine effectiveness versus LC after Omicron is a lot less than 58%.

 

Accompanying BMJ editorial:
Sivan M, Ormerod M, Maini R. Does timely vaccination help prevent post-viral conditions? BMJ 2023; 383 2633 doi:10.1136/bmj.p2633
https://www.bmj.com/content/383/bmj.p2633

Includes:
Given a plausible link between viral illnesses and long term syndromes such as chronic fatigue syndrome/myalgic encephalitis9 and fibromyalgia,10 it would be prudent to advocate timely vaccination to reduce the healthcare burden and adverse impact on the economy.