Thread by @ZdenekVrozina

In this cohort of healthcare workers infected with the original SARS2 variant, symptoms were still present even after a median of 47.5 months (!).
Brain fog may persist.
This is a prospective multicenter cohort study from Switzerland🧵

The study was designed in a fairly sensible way. The authors did not automatically treat every complaint as long COVID, but instead compared 24 chronic symptoms between the previously infected group and an uninfected control.

In this way, they identified 13 symptoms that occurred more frequently after prior infection. The most common were fatigue, smell/taste disturbance, so-called brain fog, meaning problems with concentration and cognition.

At the baseline assessment, at a median of 18.5 months after infection, 186 out of 456 infected participants - 40.8% - had at least one symptom defined in this way as post COVID (sic). That is a fairly high proportion.

When the authors looked only at people with symptoms, about 38% described themselves as having LC, while the rest had symptoms but no longer perceived themselves that way. This is interesting because it shows a difference between more objectively captured symptoms and the subjective label I have LC.

During further follow-up, the total number of symptoms decreased. The greatest decline occurred between the baseline measurement and the first follow-up, after which the trend became flatter.

At the end of follow-up, at a median of 47.5 months after infection, the symptoms had not disappeared completely. Among those who remained in the study until the final survey, 58.6% still reported at least one post-COVID symptom.

They found that both fatigue and loss of smell/taste declined significantly over time.
By contrast, brain fog decreased somewhat numerically, but the decline was not statistically significant. Cognitive difficulties may therefore be among the most persistent and long-lasting sequelae.

The study also attempted to capture the impact on everyday functioning. For this it used the PCFS scale, which assesses functional limitations after COVID. In most participants who described themselves as having long COVID, the limitations were rather mild or moderate.

Even so, in some people these impairments persisted over the long term, and those who had more marked functional limitations at the beginning often still had them later.

A strength of the study is the long follow-up period and the presence of an uninfected control group, which helps distinguish general, nonspecific complaints from symptoms more likely related to previous COVID infection.

The study also has important limitations. Much of the information was based on self report, so reporting errors are possible. A major problem was the substantial loss of participants during follow-up, which may have biased the results.

The study is fairly solid in that it includes a control group, multicenter recruitment, and long term follow up extending to almost 4 years, which is rare.

Saurer at al., Persistence of Post-Acute COVID-19 Sequelae (PASC) symptoms in healthcare workers four years after ancestral SARS-CoV-2 infection: a prospective multicentre cohort. link.springer.com/article/10.100…

Message to public health: Your long-term policy is putting healthcare at risk.
Message to workers: Wear respirators.
@szupraha @ZdravkoOnline @adamvojtech86 @adamkova_vera

The biology of COVID can lead to permanent, currently untreatable changes in a substantial part of the population. Non pharmaceutical prevention remains the most accessible foundation of protection.