A systematic review of studies revealed that the frequency of most persistent symptoms after SARS-CoV-2 infection in children and young people was similar to the uninfected (control group). In some symptoms, small but statistically significant increases were detected.
In this systematic review on persistent symptoms after SARS-CoV-2 infection in young people and children, studies with a control group and others without a control group were included. The goal was to estimate the prevalence of these symptoms in previously infected people compared to uninfected people (control group).
Comparison between the “Covid case” group with the control group (non-Covid)
The frequency of most reported persistent symptoms was similar in confirmed cases of infection and in the control group.
In symptoms associated with Long-covid, such as abdominal pain, cough, fatigue, myalgia (muscle pain), insomnia, diarrhea, fever, dizziness or dyspnea (shortness of breath), no differences were found.
On the other hand, small to residual, but statistically significant, increases were identified in some symptoms. In terms of loss of smell, there was a greater difference (8%), followed by headache (5%), cognitive difficulties (3%), sore throat (2%) and sore eyes (2%).
Prevalence of symptoms in all studies (with and without control group)
Among the studies included in the meta-analysis (five with a control group and 12 without a control group) the prevalence of post-Covid symptoms ranged from 15% (diarrhea) to 47% (fatigue).
Age was associated with a higher prevalence of all symptoms except cough. Higher study quality was associated with lower prevalence of all symptoms except loss of smell and cognitive symptoms.
Overall quality of studies on Long-covid
The authors point out that most of the included studies were of poor quality, predominantly without control groups and retrospectives, and open to selection bias.
They also present reasons for the low reliability of many of these studies:
“There are a number of reasons why the symptoms reported in many of these studies may not be specific to SARS-CoV-2, including the high prevalence of somatic symptoms such as fatigue and headache in healthy children and youth, the overlap of symptoms such as fatigue, concentration and headache, with mental health symptoms (which have gone up during the pandemic) and potential attribution bias.”
Authors’ conclusions
Some evidence (two large controlled studies) suggests that 5 to 14% of those infected may have multiple persistent symptoms for four weeks or more after an acute infection. However, most of the 14 most frequently reported symptoms were equally common in the infected than in the uninfected.
These results suggest that persistent symptoms may occur, “but the prevalence is much lower than suggested by many low-quality, uncontrolled studies.”
The fact that the (higher) quality of the study, community recruitment and diagnosis confirmed by infection tests are strongly and consistently associated with a lower prevalence of long-covid, “highlights the importance of scientific quality in the investigation of emerging phenomena, as the post-Covid syndromes”.
In particular, the critical importance of having a control group in this type of studies is highlighted.
Also read “Long-covid” essentially associated with infection beliefs.
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