Post COVID-19 condition of the Omicron variant of SARS-CoV-2

BackgroundNo epidemiological data on post coronavirus disease (COVID-19) condition due to Omicron variant has been reported yet. MethodsThis was as a single-center, cross-sectional study, that interviewed via telephone the patients who recovered from Omicron COVID-19 infection (Omicron group), and surveyed via self-reporting questionnaire those patients infected with other strains (control group). Data on patients characteristics, information regarding the acute-phase COVID-19, as well as presence and duration of COVID-19-related symptoms were obtained. Post COVID-19 condition in this study was defined as a symptom that lasted at least 2 months within 3 months since the onset of COVID-19. We investigated and compared the prevalence of post COVID-19 condition in both groups after performing propensity score matching. ResultsWe conducted interviews for 53 out of 128 patients with Omicron, and obtained 502 responses in the control group. After matching, 18 patients each in Omicron and control group had improved covariate balance of the older adult, female sex, obese patients, and vaccination status. There were no significant differences in the prevalence of each post-acute COVID-19 symptoms between the two groups. The numbers of patients with at least one post-acute COVID-19 symptom in the Omicron and the control group were 1 (5.6%) and 10 (55.6%) (p=0.003), respectively. ConclusionThe prevalence of post Omicron COVID-19 conditions was less than that of the other strains. Further research with more participants is needed to investigate the precise epidemiology of post COVID-19 condition of Omicron, and its impact on health-related quality of life and social productivity.

Predictive Model of Risk Factors of High Flow Nasal Cannula Using Machine Learning in COVID-19

BackgroundWith the rapid increase in the number of COVID-19 patients in Japan, the number of patients receiving oxygen at home has also increased rapidly, and some of these patients have died. An efficient approach to identify high-risk patients with slowly progressing and rapidly worsening COVID-19, and to avoid missing the timing of therapeutic intervention will improve patient prognosis and prevent medical complications. MethodsPatients admitted to medical institutions in Japan from November 14, 2020 to April 11, 2021 and registered in the COVID-19 Registry Japan were included. Risk factors for patients with High Flow Nasal Cannula invasive respiratory management or higher were comprehensively explored using machine learning. Age-specific cohorts were created, and severity prediction was performed for the patient surge period and normal times, respectively. ResultsWe were able to obtain a model that was able to predict severe disease with a sensitivity of 57% when the specificity was set at 90% for those aged 40-59 years, and with a specificity of 50% and 43% when the sensitivity was set at 90% for those aged 60-79 years and 80 years and older, respectively. We were able to identify lactate dehydrogenase level (LDH) as an important factor in predicting the severity of illness in all age groups. DiscussionUsing machine learning, we were able to identify risk factors with high accuracy, and predict the severity of the disease. Using machine learning, we were able to identify risk factors with high accuracy, and predict the severity of the disease. We plan to develop a tool that will be useful in determining the indications for hospitalisation for patients undergoing home care and early hospitalisation.

Risk factors associated with development and persistence of long COVID

BackgroundLong COVID has been a social concern. Though patient characteristics associated with developing long COVID are partially known, those associated with persisting it have not been identified. MethodsWe conducted a cross-sectional questionnaire survey of patients after COVID-19 recovery who visited the National Center for Global Health and Medicine between February 2020 and March 2021. Demographic and clinical data, and the presence and duration of long COVID were obtained. We identified factors associated with development and persistence of long COVID using multivariate logistic and linear regression analysis, respectively. ResultsWe analyzed 457 of 526 responses (response rate, 86.9%). The median age was 47 years, and 378 patients (84.4%) had mild disease in acute phase. The number of patients with any symptoms after 6 and 12 months after onset or diagnosis were 120 (26.3%) and 40 (8.8%), respectively. Women were at risk for development of fatigue (OR 2.03, 95% CI 1.31-3.14), dysosmia (OR 1.91, 95% CI 1.24-2.93), dysgeusia (OR 1.56, 95% CI 1.02-2.39), and hair loss (OR 3.00, 95% CI 1.77-5.09), and were at risk for persistence of any symptoms (coefficient 38.0, 95% CI 13.3-62.8). Younger age and low body mass index were risk factors for developing dysosmia (OR 0.96, 95% CI 0.94-0.98, and OR 0.94, 95% CI 0.89-0.99, respectively) and dysgeusia (OR 0.98, 95% CI 0.96-1.00, and OR 0.93, 95% CI 0.88-0.98, respectively). ConclusionWe identified risk factors for the persistence as well as development of long COVID. Many patients suffer from long-term residual symptoms, even in mild cases. SummaryOur cross-sectional questionnaire survey of patients recovering from COVID-19 revealed that women, young age, and low body mass index were risk factors for the development of multiple symptoms, and that even mild cases of COVID-19 suffered from long-term residual symptoms.

Risk factors for severity on admission and the disease progression during hospitalization in a large cohort of COVID-19 patients in Japan

ObjectivesTo investigate the risk factors contributing to severity on admission. Additionally, risk factors on worst severity and fatality were studied. Moreover, factors were compared based on three points: early severity, worst severity, and fatality. DesignA observational cohort study utilizing data entered in a Japan nationwide COVID-19 inpatient registry, COVIREGI-JP. SettingAs of August 31, 2020, 7,546 cases from 780 facilities have been registered. Participating facilities cover a wide range of hospitals where COVID-19 patients are admitted in Japan. ParticipantsParticipants who had a positive test result on any applicable SARS-CoV-2 diagnostic tests, and were admitted to participating healthcare facilities. A total of 3,829 cases were identified from January 16 to May 31, 2020, of which 3,376 cases were included in this study. Primary and secondary outcoe measuresPrimary outcome was severe or non-severe on admission, determined by the requirement of mechanical ventilation or oxygen therapy, SpO2, or respiratory rate. Secondary outcome was the worst severity during hospitalization, judged by the requirement of oxygen and/or IMV/ECMO. ResultsRisk factors for severity on admission were older age, male, cardiovascular disease, chronic respiratory disease, diabetes, obesity, and hypertension. Cerebrovascular disease, liver disease, renal disease or dialysis, solid tumor, and hyperlipidemia did not influence severity on admission; however it influenced worst severity. Fatality rates for obesity, hypertension, and hyperlipidemia were relatively lower. ConclusionsThis study segregated the comorbidities driving severity and death. It is possible that risk factors for severity on admission, worst severity, and fatality are not consistent and may be propelled by different factors. Specifically, while hypertension, hyperlipidemia, and obesity had major effect on worst severity, their impact was mild on fatality in the Japanese population. Some studies contradict our results; therefore, detailed analyses, considering in-hospital treatments, are needed for validation. Trial registrationUMIN000039873. https://upload.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000045453 Strengths and limitations of this studyO_LIIn this article, we studied the disease progression of COVID-19, by comparing the risk factors on three points: early severity, worst severity, and fatality. C_LIO_LIOur results are useful from a public health perspective, as we provide risk factors for predicting the severity on admission and disease progression from patients background factors. C_LIO_LIThis study pointed out the possibility that risk factors of the severity on admission, worst severity, and fatality are not consistent and may be propelled by different factors. C_LIO_LIOur data were collected from hundreds of healthcare facilities; thus data accuracy may be questionable. C_LIO_LIAlso, treatment type, dosage, duration, and combination varied immensely across the facilities and we did not consider treatments prior to and during hospitalization in the analysis. C_LI

Evaluation of serum antibodies against SARS-CoV-2 in healthcare workers who participated in the operation of charter flights for the evacuation of Japanese residents from Hubei Province

There are several recommendations for the use of personal protective equipment (PPE) against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. However, the selection of appropriate PPE for the current situation remains controversial. We measured serum antibody titers for SARS-CoV-2 in 10 participants who were engaged in the operation of charter flights for the evacuation of Japanese residents from Hubei Province. All participants wore PPE in accordance with Centers for Disease Control and Prevention guidelines. A total of 17 samples were tested, and all were seronegative. Hence, we conclude that the current PPE recommendation is effective to protect healthcare workers from SARS-CoV-2 infection.

Efficacy of remdesivir in Japanese patients hospitalised with COVID-19: A large observational study using the COVID-19 Registry Japan

ObjectivesAlthough several randomised controlled trials have compared the efficacy of remdesivir with that of placebo, there is limited evidence regarding its effect in the early stage of nonsevere COVID-19 cases. MethodsWe evaluated the efficacy of remdesivir on the early stage of nonsevere COVID-19 using the COVID-19 Registry Japan, a nationwide registry of hospitalised COVID-19 patients in Japan. Two regimens (start remdesivir therapy within 4 days from admission vs. no remdesivir during hospitalisation) among patients without the need for supplementary oxygen therapy were compared by a three-step processing (cloning, censoring, and weighting) method. The primary outcome was supplementary oxygen requirement during hospitalisation. Secondary outcomes were 30-day fatality risk and risk of invasive mechanical ventilation or extracorporeal membrane oxygenation (IMV/ECMO). ResultsThe data of 12,657 cases met our inclusion criteria. The start remdesivir regimen showed a lower risk of supplementary oxygen requirement (hazard ratio: 0.861, p < 0.001). Both 30-day fatality risk and risk of IMV/ECMO introduction were not significantly different between the two regimens (hazard ratios: 1.05 and 0.886, p values: 0.070 and 0.440, respectively). ConclusionsRemdesivir might reduce the risk of oxygen requirement during hospitalisation in the early stage of COVID-19; however, it had no positive effect on the clinical outcome and reduction of IMV/ECMO requirement.

Effect of evacuation of Japanese residents from Wuhan, China, on preventing transmission of novel coronavirus infection: a modelling study

ObjectiveIn late January 2020, the Japanese government carried out three evacuations by aircraft from Wuhan, China, to avoid further cases of coronavirus disease 2019 (COVID-19) among Wuhans Japanese residents. Evacuation by aircraft may be an effective countermeasure against outbreaks of infectious diseases, but evidence of its effect is scarce. This study estimated how many COVID-19 cases were prevented among the Japanese residents of Wuhan by the evacuation countermeasure. ResultsEleven imported COVID-19 cases were reported on Feb 1 from among the total 566 evacuees who returned to Japan. In the case of no evacuations being made, the cumulative number of COVID-19 cases among Wuhans Japanese residents was estimated to reach 25 (95% CI [20, 29]) on Feb 8 and 34 (95% CI [28, 40]) on Feb 15. A 1-week delay in the evacuation might be led to 14 additional cases and a 2-week delay to 23 additional cases. Evacuation by aircraft can contribute substantially to reducing the number of infected cases in the initial stage of the outbreak.

Loiasis in a Japanese traveler returning from Central Africa

We encountered a probable case ofloiasis in a returned traveler from Central Africa. A 52-year-old Japanese womanpresented to our hospital complaining of discomfort in her eyes and skin. She reportedhaving frequently visited Central Africa over many years and having been extensivelyexposed to the rainforest climate and ecosystem. Although no microfilariae werefound in her blood, there was an elevated level of IgG antibodies against thecrude antigens of<i> Brugia pahangi</i>,which have cross-reactivity with <i>Loa loa</i>.She was treated with albendazole for 21 days, after which the antigen-specificIgG level decreased and no relapse occurred.

Loiasis in a Japanese Traveler Returning from Central Africa

We encountered a probable case of loiasis in a returned traveler from Central Africa. A 52-year-old Japanese woman presented to our hospital complaining of discomfort in her eyes and skin. She reported having frequently visited Central Africa over many years and having been extensively exposed to the rainforest climate and ecosystem. Although no microfilariae were found in her blood, there was an elevated level of IgG antibodies against the crude antigens of <i>Brugia pahangi</i>, which have cross-reactivity with <i>Loa loa</i>. She was treated with albendazole for 21 days, after which the antigen-specific IgG level decreased and no relapse occurred.

Performance of Rapid Diagnostic Tests for <i>Plasmodium ovale</i> Malaria in Japanese Travellers

Background: Rapid diagnostic tests (RDTs) have widely been used in the diagnosis of malaria. Although the effectiveness of RDTs for malaria has previously been described in many reports, the low performance of RDTs particularly for <i>Plasmodium ovale</i> malaria in travellers have rarely been reported. Methods: This was retrospective cohort study conducted among Japanese travellers who were diagnosed with malaria at the National Center for Global Health and Medicine between January 2004 and June 2013. Diagnosis of malaria by microscopic examination, RDT, and polymerase chain reaction were performed for all the patients. The RDTs used in our study were Binax NOW Malaria (Binax Inc., Scarborough, Maine, USA) (BN) and SD Malaria Antigen Pf/Pan (Standard Diagnostics Inc., Korea) (SDMA). We compared the sensitivity of the RDTs of <i>P. ovale</i> malaria with that of <i>Plasmodium vivax</i> malaria. Results: A total of 153 cases of malaria were observed, of which 113 patients were Japanese travellers. Nine patients with <i>P. ovale</i> malaria and 17 patients with <i>P. vivax</i> malaria performing RDTs were evaluated. The overall sensitivity of RDTs for <i>P. ovale</i> malaria was 22.2% and that for <i>P. vivax</i> malaria was 94.1% (P < 0.001). The sensitivity of SDMA for <i>P. vivax</i> malaria was 100% and that for <i>P. ovale</i> malaria was 50%. The sensitivity of BN for <i>P. vivax</i> malaria was 90.0%; however, it was unable to detect the cases of <i>P. ovale</i> malaria. Conclusions: The sensitivity of RDTs was not high enough to diagnose <i>P. ovale</i> malaria in our study. Thus, microscopic examination is indispensable not to overlook <i>P. ovale</i> malaria.

Performance of Rapid Diagnostic Tests for <i>Plasmodium ovale</i> Malaria in Japanese Travellers

Background: Rapid diagnostic tests (RDTs) are used widely in the diagnosis of malaria. Although the effectiveness of RDTs for malaria has been described in many previous studies, the low performance of RDT particularly for <i>Plasmodium ovale</i> malaria in traveller has rarely been reported. Methods: This was a retrospective cohort study conducted on Japanese travellers diagnosed with malaria at the National Center for Global Health and Medicine between January 2004 and June 2013. The diagnosis of malaria was confirmed by microscopic examination, RDT, and polymerase chain reaction in all patients. The RDTs used in our study were Binax NOW Malaria (Binax Inc., Scarborough, Maine, USA) (BN) and SD Malaria Antigen Pf/Pan (Standard Diagnostics Inc., Korea) (SDMA). We compared the sensitivity of the RDTs to <i>P. ovale</i> malaria and <i>Plasmodium vivax</i> malaria. Results: A total of 153 cases of malaria were observed, 113 of which were found among Japanese travellers. Nine patients with <i>P. ovale</i> malaria and 17 patients with <i>P. vivax</i> malaria undergoing RDTs were evaluated. The overall sensitivity of RDTs for <i>P. ovale</i> malaria and <i>P. vivax</i> malaria was 22.2% and 94.1%, respectively (P < 0.001). The sensitivity of SDMA for <i>P. ovale</i> malaria and <i>P. vivax</i> malaria was 50% and 100%, respectively. The sensitivity of BN for <i>P. vivax</i> malaria was 90.0%, but it was ineffective in detecting the cases of <i>P. ovale</i> malaria. Conclusions: The sensitivity of RDTs was not high enough to diagnose <i>P. ovale</i> malaria in our study. In order not to overlook <i>P. ovale</i> malaria, therefore, microscopic examination is indispensable.