Epidemiology

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Opvolging en revalidatie van patiënten met aanhoudende klachten na COVID-19 in de eerste lijnPublished by: KU Leuven | Werkgroep Ontwikkeling Richtlijnen Eerste Lijn (Worel)Last published: 2023Suivi et revalidation des patients présentant des symptômes persistants après la COVID-19 en première lignePublished by: KU Leuven | Groupe de Travail Développement de recommmandations de première ligneLast published: 2023

Long COVID prevalence estimates vary widely owing to inconsistent definitions and heterogeneous methods of analysis.[15]​ Long COVID remains under-recognised in some parts of the world, with limited studies conducted in low- and middle-income countries.[16][17]​​ In the US in 2023, 6.4% of non-institutionalised adults were currently experiencing long COVID, according to one large population-based cross-sectional survey.[18]​ ​

In a systematic review and meta-analysis, approximately 63% of patients reported at least one symptom at 30 days after symptom onset/hospitalisation, with 71% reporting at least one symptom after 60 days, and 46% at 90 days or more.[19] In another systematic review, 54% of patients reported at least one symptom at 1 month, 55% of patients reported at least one symptom at 2 to 5 months, and 54% of patients reported at least one symptom at 6 months or longer.[20] However, some studies report much lower rates of continuing symptoms after 12 weeks (2.3% to 3%).[21][22]​ A study that corrected for individual symptoms present before coronavirus disease 2019 (COVID-19) and the symptom dynamics in the population without severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection found that 12.7% of patients are likely to experience long-term symptoms at 90 to 150 days after infection.[23] Persistent symptoms have been reported up to 12 months after discharge, but most people had a good and functional recovery during 1-year follow-up.[24][25]​ Persistent symptoms have also been reported at 2-year follow-up in a significant number of patients, with fatigue and muscle weakness being the most frequent.[26]

Estimates of the incidence of long COVID are highest in unvaccinated people who were hospitalised (50% to 85%).[27][28]​​​​ However, prolonged illness can occur among young adults with no underlying comorbidities, and in patients who had mild disease.[29][30]​​​ Because hospitalisation for acute COVID-19 is uncommon, most people now living with long COVID had a mild or moderate initial illness.[27][31]​​ Approximately 12% to 15% of patients who had mild symptoms still had symptoms up to 8 months later.[32] The number of symptoms at follow-up was associated with the symptom load during the acute phase of infection and the number of comorbidities in non-hospitalised patients.[33] Asymptomatic infection is associated with a lower risk of developing long-term sequelae.[34]

Epidemiological studies suggest that women are at increased risk of long COVID compared to men.[35][36]​​ Persistent symptoms have been reported in pregnant women and children. A meta-analysis found the prevalence was 25% in children and adolescents, with the most prevalent symptoms being mood symptoms, fatigue, and sleep disorders.[37] However, evidence in children is limited, heterogeneous, and based on low-quality studies.[38]

Vaccination against COVID-19 reduces the risk of long COVID.[39][40]​ In people who already have long COVID, vaccination has a variable effect on the trajectory of symptoms, but overall reduces the effect of recurrent infections, which may be a substantial contributor to persistent long COVID.[41][42]​​

A meta-analysis of 54 studies and two medical record databases from 22 countries, which included data for 1.2 million individuals, estimated that 6.2% of people who had symptomatic COVID-19 experienced at least one of the following after 3 months: persistent fatigue with pain or mood swings (3.2%), cognitive problems (2.2%), or ongoing respiratory problems (3.7%).[11] This analysis did not include patients who were infected with the Omicron variant. The risk of developing long COVID may be lower among people infected with the Omicron variant compared with those infected with previous variants.[43][44]

According to UK Office of National Statistics (ONS) data, 20% of people reporting long COVID symptoms describe them as ‘severe’.[45]

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