Virus researcher at Harvard Medical School in 1980s
Technical article: Updated estimates of the prevalence of post-acute symptoms among people with coronavirus (COVID-19) in the UK: 26 April 2020 to 1 August 2021 (UK ONS, 9/16/21)
Note 1: People with higher viral load (Ct < 30) have more Long Covid.
Note 2: The list of 12 symptoms may be too short. Doesn’t include “brain fog”. Self-reported Long Covid (Table 3) has higher percentages.
Note 3: There is a difference in studies which look at asymptomatic/symptomatic Covid (like this one), and only symptomatic Covid.
The estimated percentage of participants with self-reported long COVID 12 weeks after infection (11.7%) is notably higher than that of participants with symptoms persisting for at least 12 weeks reported in Section 4 (3.0%).
The self-reported long COVID response may better capture the relapsing nature of long COVID symptoms. Of participants who were classed as experiencing symptom discontinuation (two successive symptom-free visits) in our survival analysis approach in Section 4, 14.1% reported at least one of the 12 symptoms in a subsequent follow-up visit. Some of these participants may still describe themselves as having long COVID in our analysis in Section 5 if, from their past experience, they expect periods of improvement to be followed by relapse.
Furthermore, the percentage of participants with symptoms persisting for at least 12 weeks using the survival analysis approach increased to 6.1% when we defined symptom discontinuation as being three rather than two successive symptom-free visits (see the data tables) for full sensitivity analysis results).
It is also likely that the 12 symptoms included in the survival analysis approach do not include some symptoms often associated with long COVID, which may further explain the disparity between the estimates.
Among study participants with symptoms at the acute phase, 22.3% were estimated to be experiencing self-reported long COVID of any severity four weeks after infection (compared with 14.1% among all infections), and 17.7% at 12 weeks (compared with 11.7%).
When focussing on activity-limiting long COVID, 15.1% were estimated to be experiencing self-reported long COVID four weeks after infection (compared with 9.3% among all infections), and 11.8% at 12 weeks (compared with 7.5%).
COVID Symptom Study
Our estimates of the percentage of study participants with symptomatic COVID-19 who experience at least one of 12 symptoms continuously for at least five weeks (27.0%) or 12 weeks (6.7%) are greater than those reported by the COVID Symptom Study (13.3% at four weeks and 2.3% at 12 weeks). Like our survival analysis results reported in Section 4, the COVID Symptom Study estimates are based on a prospective symptom tracking approach, using daily data on symptoms reported by mobile phone application users who had previously tested positive by polymerase chain reaction (PCR) test.
UK National Core Studies – Longitudinal Health and Wellbeing programme
We estimated that 22.3% of study participants with symptomatic COVID-19 would describe themselves as having long COVID four weeks after infection, and 17.7% 12 weeks after infection. Slightly lower results were estimated by the UK National Core Studies -- Longitudinal Health and Wellbeing programme, which analysed data from 10 longitudinal studies of various designs, sample sizes and age ranges. These studies use retrospective reporting of symptom duration following confirmed or suspected infection. Estimates across the 10 studies ranged from 14.5% to 18.1% at four weeks after infection, and 7.8% to 17.0% at 12 weeks. When analysing studies that focussed solely on severe long COVID, the range of estimates decreased to 3.0% to 13.7% at four weeks after infection, and 1.2% to 5.4% at 12 weeks, again lower than our estimates relating to activity-limiting, self-reported long COVID of 15.1% at four weeks and 11.8% at 12 weeks.
REACT-2
All of the percentages reported in this article are lower than those from the REACT-2 study, which found that 37.7% of people continue to experience at least one symptom 12 weeks after confirmed or suspected COVID-19 infection, based on retrospective reporting of the duration of 29 individual symptoms. This estimate may be higher than our own because it includes suspected infections and is based on an extensive list of symptoms, some of which may be common in the general population at any given time (such as a runny nose and sneezing).
PHOSP-COVID
Our estimates are lower than those from the PHOSP-COVID study, in which 71% of participants did not feel fully recovered at a median of five months after hospital discharge. However, all PHOSP-COVID study participants were hospitalised with COVID-19 and were therefore likely to have generally experienced more severe acute illness compared with participants in our study, 2% of whom reported to have been hospitalised with COVID-19.
Finally. Long Covid statistics by age-group! ….
Technical article: Updated estimates of the prevalence of post-acute symptoms among people with coronavirus (COVID-19) in the UK: 26 April 2020 to 1 August 2021 (UK ONS, 9/16/21)
Note 1: People with higher viral load (Ct < 30) have more Long Covid.
Note 2: The list of 12 symptoms may be too short. Doesn’t include “brain fog”. Self-reported Long Covid (Table 3) has higher percentages.
Note 3: There is a difference in studies which look at asymptomatic/symptomatic Covid (like this one), and only symptomatic Covid.
The estimated percentage of participants with self-reported long COVID 12 weeks after infection (11.7%) is notably higher than that of participants with symptoms persisting for at least 12 weeks reported in Section 4 (3.0%).
The self-reported long COVID response may better capture the relapsing nature of long COVID symptoms. Of participants who were classed as experiencing symptom discontinuation (two successive symptom-free visits) in our survival analysis approach in Section 4, 14.1% reported at least one of the 12 symptoms in a subsequent follow-up visit. Some of these participants may still describe themselves as having long COVID in our analysis in Section 5 if, from their past experience, they expect periods of improvement to be followed by relapse.
Furthermore, the percentage of participants with symptoms persisting for at least 12 weeks using the survival analysis approach increased to 6.1% when we defined symptom discontinuation as being three rather than two successive symptom-free visits (see the data tables) for full sensitivity analysis results).
It is also likely that the 12 symptoms included in the survival analysis approach do not include some symptoms often associated with long COVID, which may further explain the disparity between the estimates.
Prevalence among symptomatic infections
Among study participants with symptoms at the acute phase, 22.3% were estimated to be experiencing self-reported long COVID of any severity four weeks after infection (compared with 14.1% among all infections), and 17.7% at 12 weeks (compared with 11.7%).
When focussing on activity-limiting long COVID, 15.1% were estimated to be experiencing self-reported long COVID four weeks after infection (compared with 9.3% among all infections), and 11.8% at 12 weeks (compared with 7.5%).
Comparison with other studies
COVID Symptom Study
Our estimates of the percentage of study participants with symptomatic COVID-19 who experience at least one of 12 symptoms continuously for at least five weeks (27.0%) or 12 weeks (6.7%) are greater than those reported by the COVID Symptom Study (13.3% at four weeks and 2.3% at 12 weeks). Like our survival analysis results reported in Section 4, the COVID Symptom Study estimates are based on a prospective symptom tracking approach, using daily data on symptoms reported by mobile phone application users who had previously tested positive by polymerase chain reaction (PCR) test.
UK National Core Studies – Longitudinal Health and Wellbeing programme
We estimated that 22.3% of study participants with symptomatic COVID-19 would describe themselves as having long COVID four weeks after infection, and 17.7% 12 weeks after infection. Slightly lower results were estimated by the UK National Core Studies -- Longitudinal Health and Wellbeing programme, which analysed data from 10 longitudinal studies of various designs, sample sizes and age ranges. These studies use retrospective reporting of symptom duration following confirmed or suspected infection. Estimates across the 10 studies ranged from 14.5% to 18.1% at four weeks after infection, and 7.8% to 17.0% at 12 weeks. When analysing studies that focussed solely on severe long COVID, the range of estimates decreased to 3.0% to 13.7% at four weeks after infection, and 1.2% to 5.4% at 12 weeks, again lower than our estimates relating to activity-limiting, self-reported long COVID of 15.1% at four weeks and 11.8% at 12 weeks.
REACT-2
All of the percentages reported in this article are lower than those from the REACT-2 study, which found that 37.7% of people continue to experience at least one symptom 12 weeks after confirmed or suspected COVID-19 infection, based on retrospective reporting of the duration of 29 individual symptoms. This estimate may be higher than our own because it includes suspected infections and is based on an extensive list of symptoms, some of which may be common in the general population at any given time (such as a runny nose and sneezing).
PHOSP-COVID
Our estimates are lower than those from the PHOSP-COVID study, in which 71% of participants did not feel fully recovered at a median of five months after hospital discharge. However, all PHOSP-COVID study participants were hospitalised with COVID-19 and were therefore likely to have generally experienced more severe acute illness compared with participants in our study, 2% of whom reported to have been hospitalised with COVID-19.
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