Abstract
Background:
The frequency, severity, and forms of symptoms months after coronavirus 2019 (COVID-19) are poorly understood, especially in community settings.
Objective:
To characterize symptoms months after community-based COVID-19.
Design:
Retrospective cohort analysis.
Setting:
Persons testing positive for SARS-CoV-2 RNA in the Johns Hopkins Health System, Maryland.
Patients:
328 consecutive persons with a positive test for SARS-CoV-2 March-May 2020.
Measurements:
symptom occurrence and severity by administered questionnaire.
Results:
Of 328 persons evaluated a median of 242 days (109 to 478 days) from initial positive SARS-CoV-2 test, 33.2% reported not being fully recovered and 4.9% reported symptoms that constrained daily activities. Compared to those who reported being fully recovered, those with post-acute sequelae were more likely to report a prior history of heart attack (p<0.01. Among those reporting long-term symptoms, men and women were equally represented (men= 34.8%, women= 34.6%), but only women reported symptoms that constrained daily activities, and 56% of them were caregivers. The types of new or persistent symptoms varied, and for many, included a deviation from prior COVID-19 health, such as being less able to exercise, walk, concentrate, or breathe.
Limitation:
Self-report of symptoms might be biased and/or caused by factors other than COVID-19.
Conclusion:
Even in a community setting, symptoms may persist months after COVID-19 reducing daily activities including caring for dependents.
Keywords: Post-COVID-19, SARS-CoV-2, sequela, long-haul
Introduction
Although more than 90% of those with COVID-19 survive, the proportion who are fully recovered 3–12 months after initial infection is varied, as are the types and frequencies of residual sequelae. Since initial infection severity might alter symptom persistence and most SARS-CoV-2 infected persons are never hospitalized, the paucity of long-term outpatient data is especially salient.
Methods and Study Design
We contacted consecutive adults with SARS-CoV-2 infection confirmed at Johns Hopkins Medical Institutions from March-May 2020 (n=328). Additional participants were sampled from the Johns Hopkins HOPE registry, which includes persons who tested positive for SARS-CoV-2 from April-November 2020 and indicated interest in research studies (n=179). Consented participants were administered a questionnaire by phone which queried the severity of initial and current symptoms and asked persons to rate their overall functional ability. Data were recorded electronically with the secure, web-based software platform RedCap (Research Electronic Data Capture) [2, 3] and analyzed in STATA/MP 16.1 (StataCorp, College Station, Texas). Study procedures were approved by the Institutional Review Board of the Johns Hopkins Medical Institutions and all participants provided consent.
Results
The 328 cases (59% women) had a mean age of 47.6 years (range, 19 to 87) (Table 1). Seven women were pregnant. The median time between testing RT-PCR positive and completing the interview was 242 days (range, 109 to 478 days). The majority of case participants remained outpatients (84%), but some individuals required hospitalization (16%). Overall, 61.9% of participants reported being fully recovered, 33.2% reported persistent symptoms but were able to perform daily activities (symptomatic but functional) and 4.9% reported symptoms that constrained daily activities (symptomatic and limited). The distribution of recovery status did not vary significantly by time since symptom onset up to 15.9 months (p=0.85). This lack of correlation between the percentage who reported symptom persistence and time from symptom onset was true both for those with symptoms but were functional (3–6 months =30.3%, 6–9 months= 32.2%, 9+ months= 34.2%) and for those with symptoms that limited daily activities, (3–6 months= 6.1%, 6–9 months = 4.1%, 9+ months = 6.1%).
Table 1:
Clinical and demographic characteristics of consecutive case series and Hope registry participants by recovery status
| Characteristics | Johns Hopkins Consecutive Case Series, N (%) | Johns Hopkins Hope Registry, N (%) | ||||||
|---|---|---|---|---|---|---|---|---|
| Fully Recovered n=203 |
Symptomatic but functional n=109 |
Symptomatic and limited n=16 |
χ2 p-value* |
Fully Recovered n=103 |
Symptomatic but functional n=58 |
Symptomatic and limited n=18 |
χ2 p-value* |
|
| Race | ||||||||
| White | 134 (66) | 73 (67) | 8 (50) | 0.40 | 87 (85) | 49 (85) | 16 (89) | 0.55 |
| Black/African American | 51 (25) | 22 (20) | 6 (37.5) | 0.27 | 6 (6) | 8 (14) | 0 (0) | 0.16 |
| Asian | 8 (4) | 4 (5.5) | 2 (12.5) | 0.25 | 5 (5) | 3 (5) | 0 (0) | 0.06 |
| Other/Mixed Race | 14 (7) | 14 (13) | 1 (6) | 0.20 | 6 (6) | 2 (3) | 2 (11) | 0.64 |
|
| ||||||||
| Median Age (range) years | 43 (19–87) | 47 (21–78) | 45 (25–63) | 44 (18–87) | 40.5 (20–67) | 41 (21–67) | ||
|
| ||||||||
| Ethnicity | ||||||||
| Hispanic | 44 (22) | 28 (26) | 2 (12.5) | 0.44 | 11 (11) | 4 (7) | 1 (6) | 0.71 |
|
| ||||||||
| Gender | ||||||||
| Male | 87 (43) | 46 (42) | 0 (0) | 0.10 | 37 (38) | 15 (28) | 4 (19) | 0.38 |
| Female | 113 (56) | 62 (57) | 16 (100) | 60 (61) | 39 (72) | 14 (82) | ||
| Non-Binary | 3 (2) | 1 (1) | 0 (0) | 1 (1) | 0 | 0 | ||
|
| ||||||||
| Education | ||||||||
| No/Primary School | 14 (7) | 7 (7) | 2 (12.5) | 0.81 | 2 (2) | 0 (0) | 0 (0) | 0.67 |
| Any High School | 28 (14) | 21 (19) | 1 (6) | 0.26 | 1 (1) | 2 (3) | 2 (11) | 0.11 |
| Any College | 89 (43) | 45 (41) | 9 (56) | 0.53 | 45 (44) | 35 (60) | 9 50) | 0.18 |
| Any Graduate School | 72 (35) | 36 (33) | 4 (25) | 0.67 | 54 (53) | 21 (36) | 7 (39) | 0.14 |
|
| ||||||||
| Higher risk occupations | ||||||||
| Health care worker in hospital | 46 (23) | 23 (21) | 5 (31) | 0.66 | 20 (19) | 9 (17) | 5 (29) | 0.46 |
| Health care worker in community | 16 (8) | 11 (10) | 1 (6) | 0.76 | 5 (5) | 7 (12) | 1 (6) | 0.37 |
| Nursing home staff | 3 (1) | 3 (3) | 1 (6) | 0.38 | 1 (1) | 0 (0) | 0 (0) | 0.86 |
| Teacher K-12 | 5 (2) | 3 (3) | 0 (0) | 0.80 | 3 (3) | 2 (3) | 0 (0) | 0.88 |
| Cleaning (office/home) | 6 (3) | 6 (5.5) | 2 (12.5) | 0.14 | -- | -- | -- | -- |
| Fire/Police/EMT | 4 (2) | 5 (5) | 0 (0) | 0.32 | 1 (1) | 1 (3) | 2 (11) | 0.11 |
| Transportation worker | 3 (1) | 3 (3) | 0 (0) | 0.62 | -- | -- | -- | -- |
|
| ||||||||
| Caregiver for a dependent in your home | ||||||||
| 69 (34) | 43 (41) | 9 (56) | 0.15 | 26 (26) | 18 (33) | 7 (44) | 0.58 | |
|
| ||||||||
| Time since infection | ||||||||
| 0–3 months | 5 (2) | 5 (5) | 0 (0) | 0.85 | 33 (32) | 14 (24) | 3 (17) | 0.49 |
| 3–6 months | 21 (10) | 10 (9) | 2 (12.5) | 26 (25) | 18 (31) | 3 (17) | ||
| 6–9 months | 109 (54) | 55 (50) | 7 (44) | 24 (23) | 13 (22) | 8 (44) | ||
| 9–11 months | 68 (33.5) | 39 (36) | 7 (44) | 20 (19) | 13 (22) | 4 (22) | ||
|
| ||||||||
|
| ||||||||
| Medical care during acute COVID-19 | ||||||||
| Hospitalized | 21 (10) | 27 (25) | 5 (31) | 0.001 | 3 (3) | 4 (7) | 5 (28) | 0.002 |
| Outpatient | 180 (90) | 82 (75) | 11 (69) | 100 (97) | 54 (93) | 13 (72) | ||
|
| ||||||||
| Baseline Comorbidities | ||||||||
| Diabetes | 14 (7) | 16 (15) | 2 (12.5) | 0.08 | 4 (4) | 4 (7) | 0 (0) | 0.70 |
| Chronic heart disease | 5 (2.5) | 8 (61) | 0 (0) | 0.08 | 4 (4) | 1 (2) | 1 (6) | 0.86 |
| History of Heart Attack | 0 (0) | 5 (5) | 0 (0) | <0.01 | 0 (0) | 1 (2) | 0 (0) | 0.69 |
| High Blood Pressure | 48 (24) | 29 (27) | 1 (6) | 0.20 | 25 (25) | 12 (22) | 2 (6) | 0.10 |
| High Cholesterol | 43 (21) | 22 (20) | 1 (6) | 0.36 | 21 (21) | 9 (17) | 0 (0) | 0.30 |
| History of Stroke | 1 (0.5) | 1 (1) | 1 (6) | 0.07 | 3 (3) | 0 (0) | 1 (6) | 0.58 |
| Autoimmune disorder | 14 (7) | 8 (7) | 0 (0) | 0.54 | 7 (7) | 6 (11) | 2 (12) | 0.72 |
| Asthma/reactive airway | 28 (14) | 20 (18) | 5 (31) | 0.14 | 11 (11) | 7 (13) | 2 (12) | 0.96 |
| Chronic lung disease | 4 (2) | 2 (2) | 0 (0) | 0.85 | 3 (3) | 0 (0) | 1 (6) | 0.58 |
| Chronic kidney disease | 3 (1) | 3 (3) | 0 (0) | 0.62 | 3 (3) | 0 (0) | 0 (0) | 0.63 |
| Cancer | 9 (4) | 5 (5) | 1 (6) | 0.94 | 4 (4) | 0 (0) | 0 (0) | 0.48 |
| Depression | 23 (11) | 16 (15) | 3 (19) | 0.54 | 14 (14) | 12 (22) | 8 (47) | 0.009 |
| Anxiety | 27 (13) | 20 (18) | 5 (31) | 0.11 | 21 (21) | 19 (35) | 9 (53) | 0.003 |
| Pregnant | 4 (2) | 3 (3) | 0 (0) | 0.75 | 2 (2) | 0 (0) | 0 (0) | 0.79 |
| Overweight/ Obese |
60 (30) | 35 (32) | 9 (56) | 0.09 | 27 (27) | 27 (50) | 7 (41) | 0.08 |
p values refer to probability that there is no difference in the factors shown across the comparison groups.
The types of new or persistent symptoms reported varied considerably in form and severity post infection, and no single symptom was present in the majority of those recovering.
The principal differences prior to the diagnosis of COVID-19 across the 3 groups were that those with persistent symptoms were more likely to report an antecedent heart attack (p<0.01). Contemporaneous with the diagnosis of COVID-19, those individuals reporting persistent symptoms were more likely to have shortness of breath, pressure in chest or tightness, lack of energy, dizziness, hallucinations, joint aches, loss of taste, loss of smell, nausea/vomiting and diarrhea compared to those fully recovered (p< 0.05)(Table 2a). There was no variability in recovery status by age and too few persons received COVID-19 specific treatments (i.e. convalescent plasma, remdesivir) (n<5) to evaluate recovery impact. Interestingly, all of those with significantly limiting symptoms were women (n=16) and 56% were responsible for the care of another person (Table 1).
Table 2a:
Frequency of initial symptoms (2 weeks pre/post testing) by recovery status in the consecutive case series.
| Fully recovered n=203 n (%) |
Symptomatic but functional n=109 n (%) |
Symptomatic and limited n=16 n (%) |
X 2 p-value* |
|
|---|---|---|---|---|
| Respiratory | ||||
| Sore Throat | 52 (26) | 33 (30) | 7 (44) | 0.24 |
| Runny Nose | 27 (13) | 21 (19) | 4 (25) | 0.22 |
| Shortness of Breath | 59 (29) | 61 (56) | 12 (75) | <0.0001 |
| Pressure in Chest/Tightness | 40 (20) | 42 (38) | 9 (56) | <0.0001 |
| Persistent Cough | 99 (49) | 65 (60) | 10 (62) | 0.14 |
| Systemic | ||||
| Any Fever | 129 (60) | 75 (68) | 11 (73) | 0.71 |
| Headache | 96 (48) | 64 (58) | 11 (69) | 0.06 |
| Joint Aches | 52 (26) | 29 (27) | 9 (56) | 0.03 |
| Muscle Aches | 111 (55) | 58 (53) | 10 (62) | 0.78 |
| Lack of Energy | 132 (65) | 94 (86) | 16 (100) | <0.0001 |
| Chills | 85 (42) | 53 (49) | 10 (62) | 0.19 |
| Gastrointestinal | ||||
| Loss of Appetite | 63 (31) | 42 (38) | 7 (44) | 0.29 |
| Nausea/Vomiting | 34 (17) | 30 (27) | 8 (50) | 0.002 |
| Diarrhea | 44 (22) | 37 (34) | 8 (50) | 0.007 |
| Neurologic | ||||
| Dizziness | 15 (7) | 12 (11) | 7 (44) | <0.0001 |
| Hallucinations | 5 (2.5) | 6 (5.5) | 4 (25) | <0.0001 |
| Loss of Smell | 86 (43) | 61 (56) | 11 (68) | 0.02 |
| Loss of Taste | 55 (27) | 46 (42) | 7 (44) | 0.02 |
Some additional differences were evident among those with persistent symptoms. Compared to the 109 who were symptomatic but still able to perform daily roles (functional), the 16 individuals with post-acute symptoms that were limiting were more likely to report an inability to walk long distances (25% vs 5.5%, p=0.007) or walk-up stairs (31% vs 6%, p=0.002) and to report new heart problems (12.5% vs 2% p =0.02) (Table 3a).
Table 3a:
Frequency and type of persistent or new symptoms post SARS-CoV-2 infection in those who have not fully recovered*
| Continued or New Symptoms | Symptomatic but functional n=109 n (%) |
Symptomatic and limited n=16 n (%) |
X 2 p-value |
|---|---|---|---|
| Muscle or Joint Aches | 14 (13) | 4 (25) | 0.20 |
| Shortness of Breath | 16 (15) | 4 (25) | 0.29 |
| Persistent cough | 2 (2) | 1 (6) | 0.28 |
| Lower energy/Increased tiredness | 30 (27) | 3 (19) | 0.46 |
| Cannot walk long distances | 6 (5.5) | 4 (25) | 0.007 |
| Cannot walk up stairs | 7 (6) | 5 (31) | 0.002 |
| Cannot exercise like I did before | 15 (14) | 5 (31) | 0.07 |
| New heart problems | 2 (2) | 2 (12.5) | 0.02 |
| Loss of Smell | 15 (14) | 1 (6) | 0.40 |
| Loss of Taste | 16 (15) | 2 (12.5) | 0.82 |
| Brain Fog/Inability to concentrate | 14 (13) | 4 (25) | 0.20 |
| Anxiety | 5 (5) | 0 (0) | 0.38 |
| Stress | 5 (5) | 0 (0) | 0.38 |
Data are self-reported by participants at the time of interview, which occurred a median of 8 months after positive SARS-CoV-2 RNA test.
Because they self-selected COVID-19 research instead of being contacted consecutively from a list testing SARS-CoV-2 positive, we separately analyzed an additional 179 individuals who participated in the Johns Hopkins HOPE registry. Those in the HOPE registry who continued to experience symptoms reported initially experiencing nearly all the presenting symptoms more often than those whose symptoms had resolved (Table 2b and 3b). Shortness of breath and pressure/tightness in the chest was a presenting symptom across both studies in those that reported symptoms but limited function.
Table 2b:
Frequency of initial symptoms (2 weeks pre/post testing) by recovery status in the HOPE registry
| Fully recovered n=103 n (%) |
Symptomatic, Functional n=58 n (%) |
Symptomatic, Limited n=18 n (%) |
X 2 p-value |
|
|---|---|---|---|---|
| Respiratory | ||||
| Sore Throat | 29 (28) | 24 (41) | 11 (61) | 0.03 |
| Runny Nose | 18 (17) | 17 (29) | 2 (11) | 0.21 |
| Shortness of Breath | 25 (24) | 21 (36) | 14 (78) | <0.0001 |
| Pressure in Chest/Tightness | 17 (38) | 14 31) | 14 (31) | <0.0001 |
| Persistent Cough | 51 (50) | 38 (65) | 14 (78) | 0.04 |
| Systemic | ||||
| Any Fever | 82 (52) | 43 (31) | 13 (72) | 0.47 |
| Headache | 51 (50) | 43 (74) | 11 (61) | 0.01 |
| Joint Aches | 16 (15) | 19 (33) | 8 (44) | 0.004 |
| Muscle Aches | 49 (48) | 36 (62) | 13 (72) | 0.09 |
| Lack of Energy | 75 (73) | 51 (88) | 17 (94) | 0.04 |
| Chills | 37 (36) | 25 (43) | 8 (44) | 0.46 |
| Gastrointestinal | ||||
| Loss of Appetite | 21 (39) | 21 39) | 10 (19) | 0.003 |
| Nausea/Vomiting | 15 (15) | 16 (28) | 4 (22) | 0.23 |
| Diarrhea | 17 (17) | 14 (24) | 7 (39) | 0.15 |
| Neurologic | ||||
| Dizziness | 4 (4) | 10 (17) | 4 (22) | <0.0001 |
| Hallucinations | 1 (1) | 5 (9) | 2 (11) | 0.06 |
| Loss of Smell | 45 (44) | 40 (69) | 15 (83) | 0.001 |
| Loss of Taste | 38 (37) | 38 (65) | 12 (67) | 0.001 |
p values refer to probability that there is no difference in the factors shown across the comparison groups.
Table 3b:
Frequency and type of persistent or new symptoms post SARS-CoV-2 infection in those who have not fully recovered as part of the HOPE registry*
| Continued or new symptoms | Symptomatic but functional n=58 n (%) |
Symptomatic and limited n=18 n (%) |
X 2 p-value |
|---|---|---|---|
| Muscle or Joint Aches | 8 (15) | 6 (33) | <0.0001 |
| Shortness of Breath | 3 (6) | 11 (61) | <0.0001 |
| Persistent cough | 3 (6) | 2 (12) | <0.0001 |
| Lower energy/Increased tiredness | 12 (22) | 17 (94) | <0.0001 |
| Cannot walk long distances | 2 (4) | 8 (44) | <0.0001 |
| Cannot walk up stairs | 3 (6) | 8 (44) | <0.0001 |
| Cannot exercise like I did before | 5 (9) | 10 (55) | <0.0001 |
| New heart problems | 5 (9) | 5 (28) | <0.0001 |
| Loss of Smell | 20 (37) | 5 (28) | <0.0001 |
| Loss of Taste | 12 (22) | 2 (11) | <0.0001 |
| Brain Fog/Inability to concentrate | 7 (13) | 10 (55) | <0.0001 |
| Anxiety | 1 (2) | 4 (22) | <0.0001 |
| Stress | 0 (0) | 3 (17) | <0.0001 |
Data are self-reported by participants at the time of interview, which occurred a median of 5.9 months after positive SARS-CoV-2 RNA test
Discussion
In this study persistent symptoms were reported by 40% of the study participants a median of 8 months (242 days) after SARS-CoV-2 infection, a majority of whom remained outpatients. No single organ system was uniformly affected, with symptoms ranging from neurocognitive to respiratory and musculoskeletal. However, many reported a clear, persistent decline from their pre-COVID-19 health condition with 4.9% reporting severe limitations in performing daily activities. Interestingly, the prevalence of persistent symptoms did not appreciably decline with time from infection onset, even for those whose symptoms were so severe as to limit their daily activities. This finding underscores the importance of efforts to prevent SARS-CoV-2 infections and research to understand and combat the long-term morbidity.
Our findings are consistent with another study that has systematically characterized the spectrum of symptoms in an ambulatory setting [5]. A median of 169 days after illness, Logue and coworkers reported that at least one symptom persisted in 49 (32.7%) of 150 Seattle, WA outpatients and 5 (31.3%) of 16 hospitalized patients. Other reports from primarily severe, and in some cases hospitalized, patients found higher estimated prevalence of persistent symptoms. For example, Carfi and coworkers reported on 143 individuals in Italy a mean of 60.3 days after initial symptom onset and only 18 persons (12.6%) were completely free of SARS-CoV-2 related symptoms [6]. Similarly, Huang and colleagues evaluated 1,733 patients six months after COVID −19 hospitalization and 76% of these patients reported at least one symptom [7]. Additional community-based efforts are needed to determine the burden of long-term COVID-19 symptoms at the population level.
Interestingly, we did not detect differences in post SARS-CoV-2 sequalae by age. However, there was a distinct sex-difference, with women having more severe post-acute symptom persistence than men. Other sex-differences have been described with SARS-CoV-2, including lower anti-SARS-CoV-2 antibody titers [8] or loss of antibodies [9]. The significance of this finding is underscored in view of the disproportionate burden of dependent care born by women, as reported by half of those with significant functional limitations in our study.
In this study, there were two sources of patients: those we consecutively called from a list of persons testing positive and the other persons who on their own initiative signed up for a COVID-19 registry and volunteered to participate in research. Although a greater proportion reporting severe limitations would be expected in the voluntary registry, the proportions were not markedly different. Instead, we noticed that those in the registry with limitations from symptoms were more likely to report nearly all symptoms on infection onset. They recalled being sicker when they were first diagnosed. In addition, those who volunteered to participate reported more depression and anxiety as pre-existing comorbidities. These differences underscore the importance of appreciating the source of persons recruited for studies of the post-COVID-19 sequelae, which might contribute to some of the differences in studies mentioned above.
One limitation of this and existing studies is the absence of detailed health examinations before and during the course of SARS-CoV-2 infection. It is possible that the recall of symptoms and their attribution to the SARS-CoV-2 infection is biased. Public awareness of the potential for symptom persistence might also affect reporting months later. However, the inclusion of all individuals who tested positive for SARS-CoV-2 may have reduced some of the bias from self-report. These consecutive case series participants reported fewer overall presenting and persistent symptoms as compared to those who entered our study by contacting the Johns Hopkins HOPE Registry. It’s likely that those who experience persistent symptoms and limitations on their daily function may be more motivated to seek out related research and report their symptoms. It is also notable that other studies have used different instruments to assess symptoms after COVID-19. For example, O’ Connor and coworkers used accepted psychometric measures to characterize the COVID-19 Yorkshire Rehabilitation Scale [10]. The apparent types and severity of post COVID-19 symptoms might differ based on the instruments used. That used in the present study is available online (supplemental data).
In summary, up to 15 months after SARS-CoV-2 infection persistent symptoms are common in ambulatory and hospitalized patients. More research is needed to understand why only some persons fully recover and to promote more rapid recovery among others.
Supplementary Material
Funding
This work was supported by the Johns Hopkins University COVID-19 Research Response Program [to P.D. and S.H.M.]; National Institute of Allergy and Infectious Disease/National Institutes of Health [3R01AI148049–21A1S1 to P.D. and D.L.T.]; BWF Maryland: Genetics, Epidemiology and Medicine Training grant [to D.D., R.M]; and National Institute on Aging/National Institutes of Health [T32AG000247 to E.A.L.].
Footnotes
Conflicts of interest
No authors report conflicts of interest with the material presented.
Data sharing
The instrument used to produce these data is available in the online supplemental data. In addition, deidentified summary data can be obtained by email to one of the communicating authors.
References
- 1.Johns Hopkins University Center for Systems Science and Engineering. COVID-19 Dashboard Available at: https://coronavirus.jhu.edu/map.html. Accessed March 4. [DOI] [PMC free article] [PubMed]
- 2.Harris PA, Taylor R, Thielke R, Payne J, Gonzalez N, Conde JG. Research electronic data capture (REDCap)--a metadata-driven methodology and workflow process for providing translational research informatics support. J Biomed Inform 2009; 42(2): 377–81. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 3.Harris PA, Taylor R, Minor BL, et al. The REDCap consortium: Building an international community of software platform partners. J Biomed Inform 2019; 95: 103208. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 4.Pisanic N, Randad PR, Kruczynski K, et al. COVID-19 Serology at Population Scale: SARS-CoV-2-Specific Antibody Responses in Saliva. Journal of Clinical Microbiology 2020; 59(1): e02204–20. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 5.Logue JK, Franko NM, McCulloch DJ, et al. Sequelae in Adults at 6 Months After COVID-19 Infection. JAMA Netw Open 2021; 4(2): e210830. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 6.Carfì A, Bernabei R, Landi F. Persistent Symptoms in Patients After Acute COVID-19. Jama 2020; 324(6): 603–5. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 7.Huang C, Huang L, Wang Y, et al. 6-month consequences of COVID-19 in patients discharged from hospital: a cohort study. Lancet 2021; 397(10270): 220–32. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 8.Dan JM, Mateus J, Kato Y, et al. Immunological memory to SARS-CoV-2 assessed for up to 8 months after infection. Science 2021; 371(6529). [DOI] [PMC free article] [PubMed] [Google Scholar]
- 9.Randad PR, Pisanic N, Kruczynski K, et al. Durability of SARS-CoV-2-specific IgG responses in saliva for up to 8 months after infection. medRxiv 2021: 2021.03.12.21252149.
- 10.O’Connor RJ, Preston N, Parkin A, et al. The COVID-19 Yorkshire Rehabilitation Scale (C19-YRS): Application and psychometric analysis in a post-COVID-19 syndrome cohort. J Med Virol 2021. Oct 21:10.1002/jmv.27415. doi: 10.1002/jmv.27415. [DOI] [PMC free article] [PubMed] [Google Scholar]
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