The longest follow-up of COVID-19 in Syrian hamsters reveals a model to study long COVID

Long COVID is one of the major enigmas left by the pandemic. Although it affects up to 30% of people who have had a SARS-CoV-2 infection, it is still unknown why some symptoms can persist for months and severely affect quality of life. To answer these questions, science needs reliable models that reproduce the disease and allow it to be studied in depth.

In this context, and within the framework of the European EPIVINF project, coordinated by IrsiCaixa, a study led by the Animal Health Research Center IRTA-CReSA has been conducted, suggesting that the Syrian golden hamster could become a very useful preclinical model for understanding long COVID. The study, published in the journal Frontiers in Microbiology, shows that these animals develop a mild and long-lasting infection, similar to what many people experience, and that they can exhibit persistent symptoms, particularly neurological ones, among the most frequent and disabling in patients with long COVID.

Persistence of viral genetic material and alterations in the immune system and behavior

To explore this possible model, the research team has carried out the longest follow-up so far of SARS-CoV-2 infection in Syrian golden hamsters, observing them for 60 days after infection. Unlike other rodents, these hamsters can be infected naturally because they express the protein that the virus uses to enter cells, and their clinical response is comparable to that of humans: neither too severe nor too mild.

The analysis has revealed that the genetic material of the virus can persist in respiratory tissues throughout the 60-day study. At the same time, deregulation of certain immune molecules, called cytokines, was observed to persist over time. Additionally, in a subgroup of animals, behavioral changes were detected, such as reduced exploration and more signs of anxiety-like behaviors, resembling the neurological alterations described in people with long COVID.

A step forward in understanding long COVID

As long COVID is a complex and still poorly understood condition, it is essential to have models that allow it to be studied in depth. This work indicates that the Syrian golden hamster could become a key tool to better understand the mechanisms of the disease and to open new avenues for therapeutic strategies that improve the quality of life of affected individuals.