Characterization of memory T cell subsets and common γ−chain cytokines in convalescent COVID-19 individuals

T cells are thought to be an important correlates of protection against SARS‐CoV2 infection. However, the composition of T cell subsets in convalescent individuals of SARS‐CoV2 infection has not been well studied. The authors determined the lymphocyte absolute counts, the frequency of memory T cell subsets, and the plasma levels of common γ−chain in 7 groups of COVID‐19 individuals, based on days since RT‐PCR confirmation of SARS‐CoV‐2 infection. The data show that both absolute counts and frequencies of lymphocytes as well as, the frequencies of CD4(+) central and effector memory cells increased, and the frequencies of CD4(+) naïve T cells, transitional memory, stem cell memory T cells, and regulatory cells decreased from Days 15–30 to Days 61–90 and plateaued thereafter. In addition, the frequencies of CD8(+) central memory, effector, and terminal effector memory T cells increased, and the frequencies of CD8(+) naïve cells, transitional memory, and stem cell memory T cells decreased from Days 15–30 to Days 61–90 and plateaued thereafter. The plasma levels of IL‐2, IL‐7, IL‐15, and IL‐21—common γc cytokines started decreasing from Days 15–30 till Days 151–180. Severe COVID‐19 patients exhibit decreased levels of lymphocyte counts and frequencies, higher frequencies of naïve cells, regulatory T cells, lower frequencies of central memory, effector memory, and stem cell memory, and elevated plasma levels of IL‐2, IL‐7, IL‐15, and IL‐21. Finally, there was a significant correlation between memory T cell subsets and common γc cytokines. Thus, the study provides evidence of alterations in lymphocyte counts, memory T cell subset frequencies, and common γ−chain cytokines in convalescent COVID‐19 individuals

Global prevalence of asymptomatic dengue infections - a systematic review and meta-analysis

Objectives: The burden of asymptomatic dengue infections is understudied. Therefore, we systematically reviewed the literature to estimate the global prevalence of asymptomatic dengue infections. Methods: We searched cross-sectional studies reporting the prevalence of asymptomatic dengue infections from PubMed, Scopus, and Embase. Prevalence of asymptomatic dengue infections was pooled and reported as proportions with a 95% confidence interval (CI). This systematic review protocol was a priori registered in The International Prospective Register of Systematic Reviews (Reg: No. CRD42020218446). Results: We included 41 studies with 131,953 cases in our analysis. The overall pooled prevalence of asymptomatic dengue infections was 59.26% (95% CI: 43.76-74.75, I2 = 99.93%), with 65.52% (95% CI: 38.73-92.32, I2 = 99.95%) during outbreaks and 30.78% (95% CI: 21.39-40.16, I2 = 98.78%) during non-outbreak periods. The pooled prevalence among the acutely infected individuals was 54.52% (95% CI: 17.73-46.76, I2 = 99.91%), whereas, among primary and secondary asymptomatic dengue infections, it was 65.36% (95% CI: 45.76-84.96, I2 = 98.82) and 48.99% (95% CI: 27.85-70.13, I2 = 99.08%) respectively. Conclusion: The majority of dengue cases are asymptomatic and may play a significant role in disease transmission. Public health strategies aimed at dengue outbreak response and mitigation of disease burden should include early detection of asymptomatic cases

Laboratory confirmation of bacterial meningitis pathogens.

<p>Laboratory confirmation of bacterial meningitis pathogens.</p

Schematic overview of the case recruitment process in bacterial meningitis surveillance.

<p>Schematic overview of the case recruitment process in bacterial meningitis surveillance.</p

Summary of meningitis case recruitment and diagnostic testing performed during March 2012—February 2013.

<p>Summary of meningitis case recruitment and diagnostic testing performed during March 2012—February 2013.</p

Hospital based sentinel surveillance of bacterial meningitis (HBSSBM) network.

<p>1- Government Medical College, Trivandrum; 2-Government TD Medical College, Allepey; 3- Institute of Child Health, Chennai; 4- Stanley Medical College, Chennai; 5- Kilpauk Medical College, Chennai; 6- Madurai Medical College, Madurai; 7- Christian Medical College, Vellore; 8- Kasturba Medical College and Hospital, Manipal; 9- Regional Medical Research Center, Bhubaneswar; 10- Indira Gandhi Institute of Medical Sciences, Shimla.</p

<i>Streptococcus pneumoniae</i> serotypes distribution between March 2012 and Feb 2013 (n = 29) and proportion covered by currently available PCV.

<p>PCV- Pneumococcal Conjugate Vaccine; NVS- Non Vaccine Serotypes.</p

Burden of bacterial meningitis in India: Preliminary data from a hospital based sentinel surveillance network.

Worldwide, acute bacterial meningitis is a major cause of high morbidity and mortality among under five children, particularly in settings where vaccination for H. influenzae type b, S. pneumoniae and N. meningitidis is yet to be introduced in the national immunization programs. Estimation of disease burden of bacterial meningitis associated with these pathogens can guide the policy makers to consider inclusion of these newer vaccines in the immunization programs. A network of hospital based sentinel surveillance was established to generate baseline data on the burden of bacterial meningitis among children aged less than 5 years in India and to provide a platform for impact assessment following introduction of the Pentavalent and Pneumococcal Conjugate Vaccines (PCV).During surveillance carried out in select hospitals across India in 2012-2013, information regarding demographics, immunization history, clinical history, treatment details and laboratory investigations viz. CSF biochemistry, culture, latex agglutination and PCR was collected from children aged 1 to 59 months admitted with suspected bacterial meningitis.A total of 3104 suspected meningitis cases were enrolled from 19,670 children admitted with fever at the surveillance hospitals. Of these, 257 cases were confirmed as cases of meningitis. They were due to S. pneumoniae (82.9%), H. influenzae type b (14.4%) and N. meningitidis (2.7%). Highest prevalence (55.3%) was observed among children 1 to 11 months. Antimicrobial susceptibility testing revealed considerable resistance among S. pneumoniae isolates against commonly used antibiotics such as cotrimoxazole, erythromycin, penicillin, and cefotaxime. More commonly prevalent serotypes of S. pneumoniae in circulation included 6B, 14, 6A and 19F. More than 90% of serotypes identified were covered by Pneumococcal Conjugate Vaccine 13.We observed that S. pneumoniae was the commonest cause of bacterial meningitis in hospitalized children under five years of age in India. Continued surveillance is expected to provide valuable information and trends in future, to take an informed decision on introduction of pneumococcal vaccination in Universal Immunization Programme in India and will also eventually help in post-vaccination impact evaluation