Association of nirmatrelvir for acute SARS-CoV-2 infection with subsequent Long COVID symptoms in an observational cohort study

The Importance of Including Long COVID Outcomes When Developing Novel Treatments for Acute COVID-19

Amid efforts to develop effective treatments for acute COVID-19, there is growing recognition of the need to address long COVID as a key outcome measure. We argue there are 7 compelling reasons to include long COVID measurements in clincal trials investigating acute COVID-19 treatments: (1) Long COVID is not rare. (2) Long COVID is debilitating to individuals and has a high societal cost. (3) Those at high risk of severe COVID-19 are also at higher risk of developing long COVID if they are infected with COVID-19. (4) Treatments for acute COVID-19 may reduce the risk of long COVID. (5) Measures exist to track long COVID. (6) Long COVID considerations are potentially important for acute COVID-19 treatment decision making. (7) Deaths and hospitalizations due to COVID-19 are increasingly rare. While not every trial needs to include assessments of long COVID, it is worth the research burden to include assessments where possible, as this could facilitate the uptake of acute COVID-19 treatments that lessen the societal burden of long COVID.

Emerging small-molecule antiviral agents in long COVID prevention

Long COVID, or Post-Acute Sequelae of COVID-19 (PASC), was characterized by persistent symptoms such as fatigue, shortness of breath, and cognitive impairments. These symptoms, emerging one to 2 months post-infection and persisting for several months, cannot be attributed to other diagnoses. The pathophysiology of long COVID remained elusive; however, emerging studies suggested multiple potential mechanisms, including the reactivation of Epstein-Barr virus, persistent SARS-CoV-2 reservoirs, neuroinflammation, and vascular damage, which may contribute to its development. Long COVID affected multiple organ systems, including respiratory, circulatory, and nervous systems, leading to a range of functional impairments. Additionally, it showed a profound impact on mental health, manifesting as anxiety and depression, which significantly degraded the quality of life. The absence of definitive treatments underscored the importance of prevention. Recent evidence indicated that early antiviral intervention-particularly with small-molecule drugs such as Metformin, Ensitrelvir, Molnupiravir, and Nirmatrelvir-may effectively reduce the incidence of long COVID. This underscored the promising role of small-molecule compounds in mitigating long-term COVID-19 consequences, offering a novel preventive strategy against long COVID and its extensive impacts on patients.

Mechanisms of long COVID and the path toward therapeutics

Long COVID, a type of post-acute sequelae of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) (PASC) defined by medically unexplained symptoms following infection with SARS-CoV-2, is a newly recognized infection-associated chronic condition that causes disability in some people. Substantial progress has been made in defining its epidemiology, biology, and pathophysiology. However, there is no cure for the tens of millions of people believed to be experiencing long COVID, and industry engagement in developing therapeutics has been limited. Here, we review the current state of knowledge regarding the biology and pathophysiology of long COVID, focusing on how the proposed mechanisms explain the physiology of the syndrome and how they provide a rationale for the implementation of a broad experimental medicine and clinical trials agenda. Progress toward preventing and curing long COVID and other infection-associated chronic conditions will require deep and sustained investment by funders and industry.

Association of nirmatrelvir-ritonavir with post-acute sequelae and mortality in patients admitted to hospital with COVID-19: a retrospective cohort study

BACKGROUND

Studies have established the short-term efficacy of nirmatrelvir-ritonavir in managing COVID-19, yet its effect on post-COVID-19 condition, especially in patients admitted to hospital, remains understudied. This study aimed to examine the effect of nirmatrelvir-ritonavir on post-COVID-19 condition among patients admitted to hospital in Hong Kong.

METHODS

This retrospective cohort study used real-world, territory-wide inpatient records, vaccination records, and confirmed COVID-19 case data from the Hong Kong Hospital Authority and Department of Health, The Government of the Hong Kong Special Administrative Region. Patients aged 18 years and older who tested positive for SARS-CoV-2 between March 11, 2022, and Oct 10, 2023, and who were admitted to hospital with COVID-19 were included. The treatment group included patients prescribed nirmatrelvir-ritonavir within 5 days of symptom onset, excluding those prescribed molnupiravir within 21 days, and the control group had no exposure to either nirmatrelvir-ritonavir or molnupiravir. The outcomes were post-acute inpatient death and 13 sequelae (congestive heart failure, atrial fibrillation, coronary artery disease, deep vein thrombosis, chronic pulmonary disease, acute respiratory distress syndrome, interstitial lung disease, seizure, anxiety, post-traumatic stress disorder, end-stage renal disease, acute kidney injury, and pancreatitis). These outcomes were evaluated starting at 21 days after the positive RT-PCR date in each respective cohort constructed for the outcome. Standardised mortality ratio weights were applied to balance covariates, and Cox proportional hazards regression was used to investigate the relationship between nirmatrelvir-ritonavir and outcomes.

FINDINGS

136 973 patients were screened for inclusion, among whom 50 055 were eligible and included in the analysis (24 873 [49·7%] were female and 25 182 [50·3%] were male). 15 242 patients were prescribed nirmatrelvir-ritonavir during acute COVID-19 and 23 756 patients were included in the control group; 11 057 patients did not meet our definition for the exposed and unexposed groups. Patients were followed up for a median of 393 days (IQR 317-489). In the nirmatrelvir-ritonavir group compared with the control group, there was a significantly lower hazard of post-acute inpatient death (hazard ratio 0·62 [95% CI 0·57-0·68]; p<0·0001), congestive heart failure (0·70 [0·58-0·85]; p=0·0002), atrial fibrillation (0·63 [0·52-0·76]; p<0·0001), coronary artery disease (0·71 [0·59-0·85]; p=0·0002), chronic pulmonary disease (0·68 [0·54-0·86]; p=0·0011), acute respiratory distress syndrome (0·71 [0·58-0·86]; p=0·0007), interstitial lung disease (0·17 [0·04-0·75]; p=0·020), and end-stage renal disease (0·37 [0·18-0·74]; p=0·0049). There was no evidence indicating difference between the groups in deep vein thrombosis, seizure, anxiety, post-traumatic stress disorder, acute kidney injury, and pancreatitis.

INTERPRETATION

This study showed extended benefits of nirmatrelvir-ritonavir for reducing the risk of post-acute inpatient death as well as cardiovascular and respiratory complications among patients admitted to hospital with COVID-19. Further research is essential to uncover the underlying mechanisms responsible for these observed negative associations and to devise effective strategies for preventing the onset of post-acute sequelae.

FUNDING

Health and Medical Research Fund, Research Grants Council theme-based research schemes, and Research Grants Council Collaborative Research Fund.

Infectious Disease Updates for Primary Care

This article summarizes the situation with public health threats for primary care patients as of early 2024 and provides updates on strategies for the prevention, diagnosis, and treatment of common infections where new treatments and vaccines are available. For flu and COVID, an update on treatment is also provided-along with pearls useful for the busy primary care provider. The authors also discuss a new treatment option for drug-resistant vulvovaginal candidiasis and provide a balanced view of the increasingly popular technique of preventing bacterial sexually transmitted infections using doxycycline after condomless sex among men who have sex with men.

Prevention of post COVID-19 condition by early treatment with ensitrelvir in the phase 3 SCORPIO-SR trial

This exploratory analysis of the double-blind, phase 3, SCORPIO-SR trial assessed the effect of ensitrelvir in preventing post coronavirus disease 2019 (COVID-19) condition (PCC). Patients with mild-to-moderate COVID-19 were randomized (1:1:1) within 120 h of symptom onset; received 5-day oral ensitrelvir 125 mg (375 mg on day 1), 250 mg (750 mg on day 1), or a matching placebo once daily; and were assessed for the severity of typical PCC symptoms using a self-administered questionnaire. In total, 341, 317, and 333 patients were assessed in the ensitrelvir 125-mg, ensitrelvir 250-mg, and placebo groups, respectively (mean age, 35.6-36.5 years; men, 53.3%-58.3%). On days 85, 169, and 337, ensitrelvir 125-mg treatment showed 32.7% (95% confidence interval [CI]: -30.6, 66.1), 21.5% (95% CI: -37.3, 55.6), and 24.6% (95% CI: -43.7, 60.9) reductions versus placebo, respectively, in the risk of any of the 14 acute-phase COVID-19 symptoms (at least one mild, moderate, or severe symptom with general health not returning to the usual level). Ensitrelvir 250-mg treatment showed 10.9% (95% CI: -67.0, 52.8), 9.5% (95% CI: -56.6, 48.0), and 30.6% (95% CI: -36.2, 65.5) risk reductions versus placebo on days 85, 169, and 337, respectively. Risk reductions were observed in any of the 4 neurological symptoms and were more pronounced among patients with high acute-phase symptom scores at baseline and among those with a baseline body mass index ≥25 kg/m2. Ensitrelvir treatment in the acute phase of COVID-19 may reduce the risk of various symptoms associated with PCC. TRIAL REGISTRATION NUMBER: jRCT2031210350.

Early biological markers of post-acute sequelae of SARS-CoV-2 infection

To understand the roles of acute-phase viral dynamics and host immune responses in post-acute sequelae of SARS-CoV-2 infection (PASC), we enrolled 136 participants within 5 days of their first positive SARS-CoV-2 real-time PCR test. Participants self-collected up to 21 nasal specimens within the first 28 days post-symptom onset; interviewer-administered questionnaires and blood samples were collected at enrollment, days 9, 14, 21, 28, and month 4 and 8 post-symptom onset. Defining PASC as the presence of any COVID-associated symptom at their 4-month visit, we compared viral markers (quantity and duration of nasal viral RNA load, infectious viral load, and plasma N-antigen level) and host immune markers (IL-6, IL-10, TNF-α, IFN-α, IFN-γ, MCP, IP-10, and Spike IgG) over the acute period. Compared to those who fully recovered, those reporting PASC demonstrated significantly higher maximum levels of SARS-CoV-2 RNA and N-antigen, burden of RNA and infectious viral shedding, and lower Spike-specific IgG levels within 9 days post-illness onset. No significant differences were identified among a panel of host immune markers. Our results suggest early viral dynamics and the associated host immune responses play a role in the pathogenesis of PASC, highlighting the importance of understanding early biological markers in the natural history of PASC.

Nirmatrelvir/ritonavir treatment and risk for postacute sequelae of COVID-19 in older Singaporeans

OBJECTIVES

Significant heterogeneity has been reported in cohort studies evaluating the impact of early oral antiviral treatment on preventing postacute sequelae after COVID-19. We evaluated the impact of early nirmatrelvir/ritonavir on risk of postacute cardiovascular, neurological, respiratory, and autoimmune diagnoses, as well as postacute symptoms amongst older Singaporeans.

METHODS

National COVID-19 registries and healthcare claims databases were used to construct a retrospective population-based cohort enrolling all Singaporeans aged ≥60 years diagnosed with SARS-CoV-2 infection in primary care during Omicron transmission (18 March 2022-4 August 2023). The cohort was divided into nirmatrelvir/ritonavir-treated and untreated groups. Between-group differences in baseline characteristics were adjusted using overlap weighting. Risks of postacute cardiovascular, neurological, respiratory, and autoimmune diagnoses and postacute symptoms (31-180 days) after SARS-CoV-2 infection were contrasted in treated/untreated groups using competing risks regressions (adjusted for demographics/vaccination status/comorbidities).

RESULTS

A total of 188 532 older Singaporeans were included; 5.8% (10 905/188 532) received nirmatrelvir/ritonavir. No significantly decreased risk of postacute sequelae (any sequelae: adjusted hazards ratio [aHR], 1.06; 0.94-1.19; cardiovascular sequelae: aHR, 1.01; 0.83-1.24; neurological sequelae: aHR, 1.09; 0.95-1.27; respiratory sequelae: aHR, 1.14; 0.84-1.55; autoimmune sequelae: aHR, 0.76; 0.53-1.09; or any postacute symptom: aHR, 0.97; 0.80-1.18) was observed up to 180 days post-infection in nirmatrelvir/ritonavir-treated individuals vs. untreated cases. Across all vaccination and age subgroups, no significantly decreased risk of any postacute diagnosis/symptom or any cardiovascular, neurological, respiratory, and autoimmune complications up to 180 days post-infection was observed.

DISCUSSION

Early outpatient receipt of nirmatrelvir/ritonavir did not significantly reduce risk of postacute cardiovascular, neurological, respiratory, and autoimmune sequelae or the risk of postacute symptoms in a boosted cohort of older Singaporeans.

Effect of Paxlovid Treatment During Acute COVID-19 on Long COVID Onset: An EHR-Based Target Trial Emulation from the N3C and RECOVER Consortia

Preventing and treating post-acute sequelae of SARS-CoV-2 infection (PASC), commonly known as Long COVID, has become a public health priority. In this study, we examined whether treatment with Paxlovid in the acute phase of COVID-19 helps prevent the onset of PASC. We used electronic health records from the National Covid Cohort Collaborative (N3C) to define a cohort of 426,352 patients who had COVID-19 since April 1, 2022, and were eligible for Paxlovid treatment due to risk for progression to severe COVID-19. We used the target trial emulation (TTE) framework to estimate the effect of Paxlovid treatment on PASC incidence. We estimated overall PASC incidence using a computable phenotype. We also measured the onset of novel cognitive, fatigue, and respiratory symptoms in the post-acute period. Paxlovid treatment did not have a significant effect on overall PASC incidence (relative risk [RR] = 0.98, 95% confidence interval [CI] 0.95-1.01). However, it had a protective effect on cognitive (RR = 0.90, 95% CI 0.84-0.96) and fatigue (RR = 0.95, 95% CI 0.91-0.98) symptom clusters, which suggests that the etiology of these symptoms may be more closely related to viral load than that of respiratory symptoms.

Colchicine-The Divine Medicine against COVID-19

Colchicine has a number of effects that suggest it may be useful in the treatment of COVID-19. Myeloid cells are a major source of dysregulated inflammation in COVID-19. The hyperactivation of the NLRP3 inflammasome and the subsequent cytokine storm take place precisely inside them and can lead to multiorgan damage and death. NLRP3 inflammasome inhibition has been assessed at micromolar colchicine concentrations which cannot be achieved in serum. However, colchicine has remarkable ability to accumulate intensively in leukocytes, where the cytokine storm is generated. Over 50 observational studies and randomized clinical trials, small randomized non-controlled trials, and retrospective cohort studies were initiated to test its healing effect in vivo, leading to conflicting, rather disappointing results. The WHO gives a "Strong recommendation against" the use of colchicine for COVID-19 treatment. This is because low doses of colchicine are always used, where the concentrations required to inhibit the NLRP3 inflammasome in leukocytes cannot be reached. Considering this, from March 2020, we started the administration of higher doses of colchicine. Our assumption was that a safe increase in colchicine doses to reach micromolar concentrations in leukocytes will result in NLRP3 inflammasome/cytokine storm inhibition. We demonstrated that in 785 inpatients treated with increasing doses of colchicine, mortality fell between two and seven times. Our data, including a large number of COVID-19 outpatients, showed that nearly 100% of the patients treated with this therapeutic regimen escaped hospitalization. In addition, post-COVID-19 symptoms in those treated with colchicine were significantly rarer. As a large number of viruses can overactivate the NLRP3 inflammasome (like seasonal influenza), we are convinced that higher colchicine doses would be useful in these cases as well.

The efficacy of antivirals, corticosteroids, and monoclonal antibodies as acute COVID-19 treatments in reducing the incidence of long COVID: a systematic review and meta-analysis

BACKGROUND

Whether treatment during acute COVID-19 results in protective efficacy against long COVID incidence remains unclear.

OBJECTIVES

To assess the relationship between acute COVID-19 treatments of antivirals, corticosteroids, and monoclonal antibodies (mAbs) and long COVID incidence, and their effects in different populations and individual symptoms.

METHODS

A systematic review and meta-analysis.

DATA SOURCES

Searches were conducted up to January 29, 2024 in PubMed, Medline, Web of Science, and Embase.

STUDY ELIGIBILITY CRITERIA

Articles that reported long COVID incidence post-acute COVID with a follow-up of at least 30 days with no language restrictions.

PARTICIPANTS

Patients with a COVID-19 diagnosis history.

INTERVENTIONS

Patients treated with antivirals, corticosteroids or mAbs.

ASSESSMENT OF RISK OF BIAS

Quality assessment was based on the Newcastle-Ottawa scale, risk of bias in nonrandomized studies of interventions-I and Cochrane risk of bias tool.

METHODS OF DATA SYNTHESIS

Basic characteristics were documented for each study. Random forest model and meta-regression were used to evaluate the correlation between treatments and long COVID.

RESULTS

Our search identified 2363 records, 32 of which were included in the qualitative synthesis and 25 included into the meta-analysis. Effect size from 14 papers investigating acute COVID-19 antiviral treatment concluded its protective efficacy against long COVID (OR, 0.61; 95% CI, 0.48-0.79; p 0.0002); however, corticosteroid (OR, 1.57; 95% CI, 0.80-3.09; p 0.1913), and mAbs treatments (OR, 0.94; 95% CI, 0.56-1.56; p 0.8012) did not generate such effect. Subsequent subgroup analysis revealed that antivirals provided stronger protection in the aged, male, unvaccinated and nondiabetic populations. Furthermore, antivirals effectively reduced 8 out of the 22 analysed long COVID symptoms.

CONCLUSIONS

Our meta-analysis determined that antivirals reduced long COVID incidence across populations and should thus be recommended for acute COVID-19 treatment. There was no relationship between mAbs treatment and long COVID, but studies should be conducted to clarify acute COVID-19 corticosteroids' potential harmful effects on the post-acute phase of COVID-19.

Exploring the Complexities of Long COVID

Since the emergence of the SARS-CoV-2 virus in 2019, nearly 700 million COVID-19 cases and 7 million deaths have been reported globally. Despite most individuals recovering within four weeks, the Center for Disease Control (CDC) estimates that 7.5% to 41% develop post-acute infection syndrome (PAIS), known as 'Long COVID'. This review provides current statistics on Long COVID's prevalence, explores hypotheses concerning epidemiological factors, such as age, gender, comorbidities, initial COVID-19 severity, and vaccine interactions, and delves into potential mechanisms, including immune responses, viral persistence, and gut dysbiosis. Moreover, we conclude that women, advanced age, comorbidities, non-vaccination, and low socioeconomic status all appear to be risk factors. The reasons for these differences are still not fully understood and likely involve a complex relationship between social, genetic, hormonal, and other factors. Furthermore, individuals with Long COVID-19 seem more likely to endure economic hardship due to persistent symptoms. In summary, our findings further illustrate the multifaceted nature of Long COVID and underscore the importance of understanding the epidemiological factors and potential mechanisms needed to develop effective therapeutic strategies and interventions.

COVID-19 Booster Vaccination Status and Long COVID in the United States: A Nationally Representative Cross-Sectional Study

Early studies have found that the initial COVID-19 vaccination series was protective against severe symptoms and long COVID. However, few studies have explored the association of booster doses on severe disease outcomes and long COVID. This cross-sectional analysis used data from the 2022 US National Health Interview Survey data to investigate how vaccination status correlates with COVID-19 infection severity and long COVID among previously infected individuals. Participants were categorized into three groups: those who had received at least one booster, those with only the initial complete vaccination series, and those with either an incomplete series or no vaccinations. Out of 9521 survey respondents who reported a past positive COVID-19 test, 51.2% experienced moderate/severe infections, and 17.6% experienced long COVID. Multivariable regression models revealed that receiving at least one booster shot was associated with lower odds of experiencing moderate/severe symptoms (aOR = 0.78, p < 0.001) compared to those unvaccinated or with an incomplete series. Additionally, having at least one booster reduced long COVID odds by 24% (aOR = 0.76, p = 0.003). Completing only the primary vaccine series did not significantly decrease the likelihood of severe illness or long COVID. These findings support the continued promotion of booster vaccinations to mitigate long COVID risks in vulnerable populations.

Real-World Effectiveness of Nirmatrelvir in Protecting Long COVID for Outpatient Adult Patients - A Large-Scale Observational Cohort Study from the RECOVER Initiative

Paxlovid has been approved for use in patients who are at high risk for severe acute COVID-19 illness. Evidence regarding whether Paxlovid protects against Post-Acute Sequelae of SARS-CoV-2 infection (PASC), or Long COVID, is mixed in high-risk patients and lacking in low-risk patients. With a target trial emulation framework, we evaluated the association of Paxlovid treatment within 5 days of SARS-CoV-2 infection with incident Long COVID and hospitalization or death from any cause in the post-acute period (30-180 days after infection) using electronic health records from the Patient-Centered Clinical Research Networks (PCORnet) RECOVER repository. The study population included 497,499 SARS-CoV-2 positive patients between March 1, 2022, to February 1, 2023, and among which 165,256 were treated with Paxlovid within 5 days since infection and 307,922 were not treated with Paxlovid or other COVID-19 treatments. Compared with the non-treated group, Paxlovid treatment was associated with reduced risk of Long COVID with a Hazard Ratio (HR) of 0.88 (95% CI, 0.87 to 0.89) and absolute risk reduction of 2.99 events per 100 persons (95% CI, 2.65 to 3.32). Paxlovid treatment was associated with reduced risk of all-cause death (HR, 0.53, 95% CI 0.46 to 0.60; risk reduction 0.23 events per 100 persons, 95% CI 0.19 to 0.28) and hospitalization (HR, 0.70, 95% CI 0.68 to 0.73; risk reduction 2.37 events per 100 persons, 95% CI 2.19 to 2.56) in the post-acute phase. For those without documented risk factors, the associations (HR, 1.03, 95% CI 0.95 to 1.11; risk increase 0.80 events per 100 persons, 95% CI -0.84 to 2.45) were inconclusive. Overall, high-risk, nonhospitalized adult patients with COVID-19 who were treated with Paxlovid within 5 days of SARS-CoV-2 infection had a lower risk of Long COVID and all-cause hospitalization or death in the post-acute period. However, Long COVID risk reduction with Paxlovid was not observed in low-risk patients.

Persistent Neurological Deficits in Mouse PASC Reveal Antiviral Drug Limitations

Post-Acute Sequelae of COVID-19 (PASC) encompasses persistent neurological symptoms, including olfactory and autonomic dysfunction. Here, we report chronic neurological dysfunction in mice infected with a virulent mouse-adapted SARS-CoV-2 that does not infect the brain. Long after recovery from nasal infection, we observed loss of tyrosine hydroxylase (TH) expression in olfactory bulb glomeruli and neurotransmitter levels in the substantia nigra (SN) persisted. Vulnerability of dopaminergic neurons in these brain areas was accompanied by increased levels of proinflammatory cytokines and neurobehavioral changes. RNAseq analysis unveiled persistent microglia activation, as found in human neurodegenerative diseases. Early treatment with antivirals (nirmatrelvir and molnupiravir) reduced virus titers and lung inflammation but failed to prevent neurological abnormalities, as observed in patients. Together these results show that chronic deficiencies in neuronal function in SARS-CoV-2-infected mice are not directly linked to ongoing olfactory epithelium dysfunction. Rather, they bear similarity with neurodegenerative disease, the vulnerability of which is exacerbated by chronic inflammation.

Long COVID symptoms after 8-month recovery: persistent static lung hyperinflation associated with small airway dysfunction

BACKGROUND

Limited research has investigated the relationship between small airway dysfunction (SAD) and static lung hyperinflation (SLH) in patients with post-acute sequelae of COVID-19 (PASC) especially dyspnea and fatigue.

METHODS

64 patients with PASC were enrolled between July 2020 and December 2022 in a prospective observational cohort. Pulmonary function tests, impulse oscillometry (IOS), and symptom questionnaires were performed two, five and eight months after acute infection. Multivariable logistic regression models were used to test the association between SLH and patient-reported outcomes.

RESULTS

SLH prevalence was 53.1% (34/64), irrespective of COVID-19 severity. IOS parameters and circulating CD4/CD8 T-cell ratio were significantly correlated with residual volume to total lung capacity ratio (RV/TLC). Serum CD8 + T cell count was negatively correlated with forced expiratory volume in the first second (FEV1) and forced vital capacity (FVC) with statistical significance. Of the patients who had SLH at baseline, 57% continued to have persistent SLH after eight months of recovery, with these patients tending to be older and having dyspnea and fatigue. Post-COVID dyspnea was significantly associated with SLH and IOS parameters R5-R20, and AX with adjusted odds ratios 12.4, 12.8 and 7.6 respectively. SLH was also significantly associated with fatigue.

CONCLUSION

SAD and a decreased serum CD4/CD8 ratio were associated with SLH in patients with PASC. SLH may persist after recovery from infection in a substantial proportion of patients. SAD and dysregulated T-cell immune response correlated with SLH may contribute to the development of dyspnea and fatigue in patients with PASC.