> Researchers also found that individuals who experienced long COVID were more likely to be less educated, have seasonal allergies and pre-existing health conditions, and self-report greater symptom severity than people without long COVID.
How do we know any of these symptoms were caused by COVID?
EDIT: why the downvotes, this is a genuine question.
Your point is fair in the sense that the research cited in OP establishes a correlation between these symptoms and SARS-CoV-2 infection. The cited research does not claim causation. Indeed there are many confounding factors such as pre-existing chronic conditions that were not controlled for in the study.
That said, you're probably getting some down votes because it's well established in the scientific literature that COVID-19 encompasses all of these symptoms.
How do we know? That's literally what research is for. Researchers compare symptoms of people who do vs people who don't have covid. Math tells us if the results are statistically significant. Biology helps explain the mechanisms causing it.
I'm sorry but the symptoms reported "fatigue, shortness of breath, brain fog, stress or anxiety, altered taste or smell, body aches and muscle pain, insomnia, headaches, joint pain, and congestion" could all (except for altered taste/smell perhaps) be linked to a million other causes.
What makes you so confident that these are due to COVID?
As far as I know, it's not like we've discovered an exact biological mechanism we can point to and say "that's what causes long COVID".
Yes, they could be linked to other causes. In fact, those things ARE linked to other causes. But it seems like they are ALSO related to long covid. That's what the research is trying to prove or disprove.
It does this by looking at data from people who do have covid vs people who don't. And the research find that people who have covid, are more likely to have these symptoms. And they had more of these symptoms vs non-covid people 30 to 250 days later.
As with all research, this is just one study of 300 patients. So no one should be "confident" based on just this study. That's why other researchers will try to do similar studies.
That's also why studies explain a lot about who they studied. For example, in this study 70% of people who had covid were women. Could these symptoms be caused by their gender? Probably more likely the covid, but maybe that's something to consider for studies in case it shows up again in the future.
Downvoted both because of your tone and because other mechanisms (like people who’ve had Covid becoming more prone to reporting symptoms caused by other sources) could explain these results.
But that paper makes no such claim. They didn't check symptoms for the same subjects both before and after infection, so we can't be confident of causality.
How do we know any of these symptoms were caused by COVID?
EDIT: why the downvotes, this is a genuine question.