Viral load of SARS-CoV-2 Omicron BA.5 is lower than that of BA.2 despite the higher infectivity of BA.5.

BACKGROUND: Sublineage BA.5 of the SARS-CoV-2 Omicron variant rapidly spread and replaced BA.2 in July 2022 in Tokyo. A high viral load can be a possible cause of high transmissibility. METHODS AND RESULTS: The copy numbers of SARS-CoV-2 in nasopharyngeal swab samples obtained from all patients visiting the hospital where this research was conducted were measured using reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Viral genotypes were determined using PCR-based melting curve analysis. Next, whole-genome sequencing was performed using approximately one fifth of the samples to verify the viral genotypes determined using PCR. Then, the copy numbers of the BA.1, BA.2, and BA.5 cases were compared. Contrary to expectations, the copy numbers of the BA.5 cases (median 4.7 × 104 copies/µL, n = 291) were significantly (p = .001) lower than those of BA.2 cases (median 1.1 × 105 copies/µL, n = 184). There was no significant difference (p = .44) between the BA.5 and BA.1 cases (median, 3.3 × 104 copies/µL; n = 215). CONCLUSION: The results presented here suggest that the increased infectivity of BA.5 is not caused by higher viral loads, but presumably by other factors such as increased affinity to human cell receptors or immune escape due to its L452R mutation.

Impact of Treatment with Anti-CD20 Monoclonal Antibody on the Production of Neutralizing Antibody Against Anti-SARS-CoV-2 Vaccination in Mature B-Cell Neoplasms.

Background and Purpose: Anti-CD20 monoclonal antibodies (MoAbs), rituximab (RIT), and obinutuzumab (OBZ) are the central components of immunochemotherapy for B-cell lymphoma (BCL). However, these agents potentially cause B-cell depletion, resulting in the impairment of antibody (Ab) production. During the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic, the optimal prediction of Ab response against anti-SARS-CoV-2 vaccination is critically important in patients with BCL treated by B-cell depletion therapeutics to prevent coronavirus disease 2019 (COVID-19). Patients and Methods:  We investigated the effect of using RIT and/or OBZ on the Ab response in 131 patients with various types of BCL who received the second SARS-CoV-2 mRNA vaccine either after, during, or before immunochemotherapy containing B-cell-depleting moiety between June and November 2021 at seven institutes belonging to the Kyoto Clinical Hematology Study Group. The SARS-Cov-2 neutralizing Ab (nAb) was measured from 14 to 207 days after the second vaccination dose using the iFlash3000 automatic analyzer and the iFlash-2019-nCoV Nab kit. Results: Among 86 patients who received the vaccine within 12 months after B-cell depletion therapy, 8 (9.3%) were seropositive. In 30 patients who received the vaccine after 12 months from B-cell depletion therapy, 22 (73%) were seropositive. In 15 patients who were subjected to B-cell depletion therapy after vaccination, 2 (13%) were seropositive. The multivariate analysis indicated that an interval of 12 months between B-cell depletion therapy and the subsequent vaccination was significantly associated with effective Ab production. Receiver operating characteristic curve analysis identified the optimal threshold period after anti-CD20 MoAb treatment, which determines the seropositivity against SARS-CoV-2, to be 342 days. Conclusion: The use of anti-CD20 MoAb within 12 months before vaccination is a critical risk for poor Ab response against anti-SARS-CoV-2 vaccination in patients with BCL.

Clinical Implication of the Effect of the Production of Neutralizing Antibodies Against SARS-Cov-2 for Chronic Immune Thrombocytopenia Flare-Up Associated with COVID-19 Infection: A Case Report and the Review of Literature.

Previous studies have demonstrated that the appropriate production of serum anti-severe acute respiratory syndrome coronavirus 2 (SARS-Cov-2) neutralizing antibody (nAb) plays a critical role in the recovery from coronavirus disease 2019 (COVID-19); however, the role of nAb production in the recovery from a flare-up of chronic immune thrombocytopenia (ITP) has been unknown. We here report the first retrospectively investigated case of serum anti-SARS-Cov-2 nAb production during chronic ITP flare-up triggered by COVID-19. A 79-year-old woman with a history of corticosteroid-refractory ITP visited our hospital complaining of fever, cough, and sore throat for 4 days. Although chronic ITP was controlled by 12.5 mg of eltrombopag (EPAG) every other day, laboratory tests showed a decreased peripheral blood platelet count of 15.0 × 109/L, which indicated worsening thrombocytopenia. Meanwhile, PCR testing of a nasopharyngeal swab revealed that the patient was positive for SARS-Cov-2, and a computed tomography scan revealed bilateral pneumonia. On the basis of the flare-up of chronic ITP associated with COVID-19 pneumonia which was determined as a moderately severe status according to the WHO clinical progression scale, intravenous immunoglobulin therapy for 5 days (days 0-4) and antiviral therapy were added on top of EPAG, which only resulted in a transient increase in the platelet count for several days. After decreasing to 8.0 × 109/L on day 13, the platelet count increased from day 16, coinciding with a positive detection for serum nAb against SARS-Cov-2. Although the increased dose up to 50 mg/day of EPAG was challenged during the clinical course, rapid dose reduction did not cause another relapse. In addition, no thrombotic or bleeding event was seen. These collectively suggest the vital role of the production of anti-SARS-Cov-2 nAb and improvement of clinical symptoms for recovery from a flare-up of chronic ITP in our case.

Viral load of SARS-CoV-2 Omicron is not high despite its high infectivity.

Patients infected with the Omicron variant of severe acute respiratory syndrome coronavirus 2 has increased worldwide since the beginning of 2022 and the variant has spread more rapidly than the Delta variant, which spread in the summer of 2021. It is important to clarify the cause of the strong transmissibility of the Omicron variant to control its spread. In 694 patients with coronavirus disease 2019, the copy numbers of virus in nasopharyngeal swab-soaked samples and the viral genotypes were examined using quantitative polymerase chain reaction (PCR) and PCR-based melting curve analysis, respectively. Whole-genome sequencing was also performed to verify the viral genotyping data. There was no significant difference (p = 0.052) in the copy numbers between the Delta variant cases (median 1.5 × 105 copies/µl, n = 174) and Omicron variant cases (median 1.2 × 105 copies/µl, n = 328). During this study, Omicron BA.1 cases (median 1.1 ×105 copies/µl, n = 275) began to be replaced by BA.2 cases (median 2.3 × 105 copies/µl, n = 53), and there was no significant difference between the two groups (p = 0.33). Our results suggest that increased infectivity of the Omicron variant and its derivative BA.2 is not caused by higher viral loads but by other factors, such as increased affinity to cell receptors or immune escape.

Neutralizing Type I Interferon Autoantibodies in Japanese Patients with Severe COVID-19.

PURPOSE: Autoantibodies (aAbs) to type I interferons (IFNs) have been found in less than 1% of individuals under the age of 60 in the general population, with the prevalence increasing among those over 65. Neutralizing autoantibodies (naAbs) to type I IFNs have been found in at least 15% of patients with life-threatening COVID-19 pneumonia in several cohorts of primarily European descent. We aimed to evaluate the prevalence of aAbs and naAbs to IFN-α2 or IFN-ω in Japanese patients who suffered from COVID-19 as well as in the general population. METHODS: Patients who suffered from COVID-19 (n = 622, aged 0-104) and an uninfected healthy control population (n = 3,456, aged 20-91) were enrolled in this study. The severities of the COVID-19 patients were as follows: critical (n = 170), severe (n = 235), moderate (n = 112), and mild (n = 105). ELISA and ISRE reporter assays were used to detect aAbs and naAbs to IFN-α2 and IFN-ω using E. coli-produced IFNs. RESULTS: In an uninfected general Japanese population aged 20-91, aAbs to IFNs were detected in 0.087% of individuals. By contrast, naAbs to type I IFNs (IFN-α2 and/or IFN-ω, 100 pg/mL) were detected in 10.6% of patients with critical infections, 2.6% of patients with severe infections, and 1% of patients with mild infections. The presence of naAbs to IFNs was significantly associated with critical disease (P = 0.0012), age over 50 (P = 0.0002), and male sex (P = 0.137). A significant but not strong correlation between aAbs and naAbs to IFN-α2 existed (r = - 0.307, p value < 0.0001) reinforced the importance of measuring naAbs in COVID-19 patients, including those of Japanese ancestry. CONCLUSION: In this study, we revealed that patients with pre-existing naAbs have a much higher risk of life-threatening COVID-19 pneumonia in Japanese population.

Viral loads and profile of the patients infected with SARS-CoV-2 Delta, Alpha, or R.1 variants in Tokyo.

The rapid spread of the Delta variant of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) became a serious concern worldwide in summer 2021. We examined the copy number and variant types of all SARS-CoV-2-positive patients who visited our hospital from February to August 2021 using polymerase chain reaction (PCR) tests. Whole genome sequencing was performed for some samples. The R.1 variant (B.1.1.316) was responsible for most infections in March, replacing the previous variant (B.1.1.214); the Alpha (B.1.1.7) variant caused most infections in April and May; and the Delta variant (B.1.617.2) was the most prevalent in July and August. There was no significant difference in the copy numbers among the previous variant cases (n = 29, median 3.0 × 104 copies/µl), R.1 variant cases (n = 28, 2.1 × 105 copies/µl), Alpha variant cases (n = 125, 4.1 × 105 copies/µl), and Delta variant cases (n = 106, 2.4 × 105 copies/µl). Patients with Delta variant infection were significantly younger than those infected with R.1 and the previous variants, possibly because many elderly individuals in Tokyo were vaccinated between May and August. There was no significant difference in mortality among the four groups. Our results suggest that the increased infectivity of Delta variant may be caused by factors other than the higher viral loads. Clarifying these factors is important to control the spread of Delta variant infection.

SARS-CoV-2 R.1 lineage variants that prevailed in Tokyo in March 2021.

The spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants, such as B.1.1.7 and B.1.351, has become a crucial issue worldwide. Therefore, we began testing all patients with COVID-19 for the N501Y and E484K mutations by using polymerase chain reaction (PCR)-based methods. Nasopharyngeal swab samples from 108 patients who visited our hospital between February and April 2021 were analyzed. The samples were analyzed using reverse transcription-PCR with melting curve analysis to detect the N501Y and E484K mutations. A part of the samples was also subjected to whole-genome sequencing (WGS). Clinical parameters such as mortality and admission to the intensive care unit were analyzed to examine the association between increased disease severity and the E484K mutation. The ratio of cases showing the 501N + 484K mutation rapidly increased from 8% in February to 46% in March. WGS revealed that the viruses with 501N + 484K mutation are R.1 lineage variants. Evidence of increased disease severity related to the R.1 variants was not found. We found that the R.1 lineage variants rapidly prevailed in Tokyo in March 2021, which suggests the increased transmissibility of R.1 variants, while they showed no increased severity.

Seroprevalence of SARS‐CoV‐2 in Utsunomiya City, Greater Tokyo, after the first pandemic in 2020

BackgroundA seroepidemiological study was conducted on a random sample of households in Utsunomiya City, Tochigi Prefecture, Greater Tokyo, Japan, to assess the seroprevalence of SARS‐CoV‐2.MethodsThe level of IgG antibodies in the blood of the recruited subjects was assessed using chemiluminescence immunoassay analysis. In addition, the population‐based prevalence of SARS‐CoV‐2 was estimated.ResultsThree positive afebrile cases were confirmed. The estimated unweighted prevalence and weighted prevalence of SARS‐CoV‐2 infection were 0.40% and 1.23%, respectively.ConclusionsThis study suggests that the prevalence of SARS‐CoV‐2 may have been underestimated. Wider testing strategies may lead to revealing more SARS‐CoV‐2 cases.

Clinical validation of an immunochromatographic SARS-Cov-2 IgM/IgG antibody assay with Japanese cohort.

BACKGROUND: The coronavirus disease 2019 (COVID-19) has become a major health threat. To overcome COVID-19, appropriate diagnosis methods are urgently needed. The aim of this study was to clinically evaluate the colloidal gold immunochromatography assay for SARS-Cov-2 IgM/IgG antibody (Ab). METHODS: Patients confirmed COVID-19 (n = 51) were recruited prospectively from the Musashino Red Cross hospital and Tokyo Medical and Dental University Medical Hospital, between March and May 2020. And the analytical specificity was assessed with serum samples of patients without COVID-19 (n = 100) collected between August to September 2019 before SARS-CoV-2 was first reported in China. RESULTS: Among COVID-19 patients, a total of 87 serum samples were tested for SARS-Cov-2 IgM/IgG Ab assay. IgM was detected 71.0 %, 86.9 %, and 83.3 % at day8-14, 15-28, >29 after symptom onset and IgG was detected in 81.6 %, 87.0 %, and 94.4 %, respectively. The sensitivity of IgM and IgG Ab after day8 assay was significantly higher than before day7, respectively (p=0.0016, 0.0003). There were no positive results in 100 serum samples from patients without COVID-19. CONCLUSION: The SARS-Cov-2 IgM/IgG Ab assay had 79.7% / 86.1% sensitivity (the 8 days after from onset) and 100% specificity in this population.