PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Pandemics”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 37 records · Page 2Linked to original sources
PubMedDate not supplied

[Antigenic and biological characteristics of influenza A1 viruses isolated in the 1977 pandemic].

Investigations of the antigenic and biological properties of the causative agents of the 1977 influenza epidemic revealed their appurtenance to the old subtype A1 of influenza virus which had disappeared from circulation 20 years ago. A comparative study of A1 viruses isolated in 1947--1956 and A1/77 established closer relationship of the latter to the causative agents of 1949 and 1950 epidemics. The "old" and newly isolated viruses 4ere also closely related biologically. The similarity of influenza A1/77 viruses with the agents of the pandemic cycle of A1 in 1947--1956 is a convincing confirmation of the hypothesis of Francis-Davenport and Smorodintsev-Luzyanina.

Antigens, Viral↗
PubMed2026

The impact of alcohol sale restrictions on unnatural deaths during the COVID-19 pandemic in Johannesburg, South Africa.

The COVID-19-related restrictions on the sale of alcohol in South Africa presented a unique opportunity to examine the association between alcohol availability and the prevalence of unnatural deaths. The study sample included all unnatural deaths investigated by the Johannesburg Forensic Pathology Services Medico-Legal Laboratory during the four COVID-19 alcohol restriction periods compared to the same time periods in the previous year when there were no restrictions. When alcohol sales were initially prohibited, there was a 54.2% decrease in cases of unnatural deaths (p&#x2009;<&#x2009;0.05), suggesting a link between alcohol use and the occurrence of such deaths. Over all four periods of alcohol sale bans, there was a total reduction of unnatural deaths by 26.4% with declining frequencies in all demographics. There were significant decreases (p&#x2009;<&#x2009;0.05) in the frequency of deaths in males, Black and Coloured individuals, and the 21-40 years age group. Deaths whose circumstances were a result of motor vehicle accidents, pedestrian vehicle accidents, and firearm discharges decreased significantly (p&#x2009;<&#x2009;0.05). The cause of death due to blunt forces trauma and gunshot wounds also significantly decreased (p&#x2009;<&#x2009;0.05). This study highlights the significant impact alcohol consumption has on mortality in South Africa.

Humans↗
PubMed2025

Genomic and clinical epidemiology of SARS-CoV-2 in coastal Kenya: insights into variant circulation, reinfection, and multiple lineage importations during a post-pandemic wave.

BACKGROUND: Between November 2023 and March 2024, coastal Kenya experienced another wave of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections detected through our continued genomic surveillance. Herein, we report the clinical and genomic epidemiology of SARS-CoV-2 infections from 179 individuals (a total of 185 positive samples) residing in the Kilifi Health and Demographic Surveillance System (KHDSS) area (~&#x2009;900 km2). METHODS: We analyzed genetic, clinical, and epidemiological data from SARS-CoV-2 positive cases across pediatric inpatient, health facility outpatient, and homestead community surveillance platforms. Phylogenetic analyses were performed using maximum-likelihood and Bayesian frameworks. Temporal trends were summarized, comparisons conducted using Kruskal-Wallis and Wilcoxon tests, and associations examined using univariate and multivariable logistic regression models. RESULTS: Sixteen SARS-CoV-2 lineages within 3 subvariants [XBB.2.3-like (58.4%), JN.1-like (40.5%), and XBB.1-like (1.1%)] were identified. The symptomatic infection rate was estimated at 16.0% (95% CI, 11.1-23.9%) based on community testing regardless of symptom status and did not differ across the subvariants (p&#x2009;=&#x2009;0.13). The most common infection symptoms in community cases were cough (49.2%), fever (27.0%), sore throat (7.3%), headache (6.9%), and difficulty in breathing (5.5%). One case succumbed to the infection. Genomic analysis of the virus from serial positive samples confirmed repeat infections among 5 participants under follow-up (median interval 21&#xa0;days, range 16-95&#xa0;days); in 4 participants, the same virus lineage was responsible in both episodes, whereas 1 participant had a different lineage in the second compared with the first episode. Phylogenetic analysis including&#x2009;>&#x2009;18,000 contemporaneous global sequences provided evidence for at least 38 independent virus introduction events into the study area (KHDSS) during the wave, the majority likely originating in North America and Europe. CONCLUSIONS: Our study highlights that coastal Kenya, like most other localities, continues to face new SARS-CoV-2 infection waves characterized by circulation of new variants, multiple lineage importations, and reinfections. Locally, the virus may circulate unrecognized, as most infections are asymptomatic in part due to high population immunity after several waves of infection. Our findings highlight the need for sustained SARS-CoV-2 surveillance to inform appropriate public health responses, such as scheduled vaccination for populations at risk of severe infection.

COVID-19↗
PubMed2025

Multi-scale phylodynamic modelling of rapid punctuated pathogen evolution.

Computational multi-scale pandemic modelling remains a major and timely challenge. Here we identify specific requirements for a new class of models simulating pandemics across three scales: (1) pathogen evolution, often punctuated by the rapid emergence of new variants, (2) human interactions within a heterogeneous population, and (3) public health responses which constrain individual actions to control the disease transmission. We then present a pandemic modelling framework satisfying these requirements and capable of simulating feedback loops between dynamics unfolding at these different scales. The developed framework comprises a stochastic agent-based model of pandemic spread, coupled with a phylodynamic model that incorporates within-host pathogen evolution. It is validated with a case study, modelling the punctuated evolution of SARS-CoV-2, based on global and contemporary genomic surveillance data, which captures a large heterogeneous population. We demonstrate that the model replicates the essential features of the COVID-19 pandemic and virus evolution, while retaining computational tractability and scalability.

SARS-CoV-2↗
PubMed2025

Whole-genome sequencing, strain composition, and predicted antimicrobial resistance of Streptococcus pneumoniae causing invasive disease in England in 2017-20: a prospective national surveillance study.

BACKGROUND: Surveillance of the invasive disease burden caused by Streptococcus pneumoniae in England is performed by the UK Health Security Agency (UKHSA). In 2017, UKHSA switched from phenotypic methods to whole-genome sequencing (WGS) approaches for pneumococcal surveillance. Here, we present the first results of national WGS surveillance, up to the start of the COVID-19 pandemic, with the aim of describing the population genomics of this important pathogen. METHODS: We examined prospective national surveillance data from England, using bacterial isolates from cases of invasive pneumococcal disease (IPD) submitted to the national reference laboratory at UKHSA. A bioinformatic pipeline was developed to quality control WGS data and routinely report species and serotype. We assembled isolate data, assigned global pneumococcal sequencing clusters (GPSCs), and predicted antimicrobial resistance (AMR) profiles for isolates that passed further quality control. We collected additional data on patient outcomes and characteristics using enhanced surveillance questionnaires completed by patients' general practitioners. We used logistic regression analysis to assess the effects of various genomic and patient characteristics on the outcomes of IPD. FINDINGS: In England, between July 1, 2017, and Feb 29, 2020, there were 15&#x2009;400 cases of IPD. From these cases, 13&#x2009;749 (89&#xb7;3%) isolates were sequenced, passed quality control, and were included in analyses. Serotype diversity was high during the study period, with 2751 (20%) isolates serotyped as 13-valent pneumococcal conjugate vaccine (PCV13) types, whereas serotype 8 was the most prevalent serotype (n=3074 [22&#xb7;4%]) overall. There were 157 GPSCs within the collection, with GSPC3 the most common, encompassing 98&#xb7;7% (3033 of 3074) of serotype 8 isolates. Most isolates (n=10&#x2009;198 [74&#xb7;2%]) did not contain AMR-associated genes. Resistance to co-trimoxazole was the most frequently predicted resistance (n=2331 [17%]), followed by resistance to tetracycline (n=1199 [8&#xb7;7%]) and &#x3b2;-lactams (n=1149 [8&#xb7;4%]). Logistic regression analysis found the presence of AMR-associated genes significantly increased the odds of patient death (odds ratio 1&#xb7;18, 95% CI 1&#xb7;01-1&#xb7;38). Some GPSCs were also associated with a significant increase in the odds of patient death, such as GPSC12 (1&#xb7;88, 1&#xb7;48-2&#xb7;38). Isolates from 2018 were associated with a significant increase in the odds of patient death (1&#xb7;12, 1&#xb7;00-1&#xb7;25), whereas younger patient age was significantly associated with a reduction in the odds of patient death compared with being aged 85 years or older. INTERPRETATION: WGS-based surveillance has allowed us to interrogate country-wide population dynamics driving changes in pneumococcal serotype frequency. Here, we observe a stable but diverse population before the COVID-19 pandemic restrictions were enforced in England, with low rates of AMR. These findings will provide the baseline for pandemic and post-pandemic data, to collectively inform implementation and development of the vaccination programme within the country. FUNDING: None.

Streptococcus pneumoniae↗
PubMed2026

RND-mediated efflux couples antimicrobial resistance and hypervirulence in contemporary Vibrio cholerae.

The prevailing view in bacterial pathogenesis is that antimicrobial resistance and virulence are constrained by evolutionary trade-offs, with resistance mechanisms imposing fitness costs that attenuate pathogenic potential. Herein we document that contemporary Vibrio cholerae clinical isolates from the ongoing seventh pandemic have circumvented this paradigm by coupling multidrug resistance with hypervirulence. We examined five geographically diverse Wave 3 isolates collected between 2017 and 2019 and compared them to early pandemic strains. These contemporary isolates exhibited both broad-spectrum antimicrobial resistance and markedly enhanced colonization capacity in the infant mouse model. Phylogenetic analysis of 67 O1 El Tor genomes spanning 1960-2019 confirmed that the isolates cluster within a representative Wave 3 sublineage. We identified the VexB RND efflux pump as a mediator of this coupled phenotype. Elevated vexB expression in the contemporary isolates conferred resistance to multiple antibiotic classes, while vexB inactivation simultaneously impaired resistance and colonization. This dual function was not observed in early pandemic strains, consistent with a recent evolutionary adaptation. VexB-mediated hypervirulence occurred through multiple pathways independent of cholera toxin and toxin-coregulated pilus production levels. VexB deletion impaired bacterial adherence to intestinal epithelial cells, impaired motility, and increased susceptibility to membrane-active antimicrobials. In contrast, laboratory evolution under antibiotic pressure alone generated resistant but avirulent strains, demonstrating that complex selective forces in nature enabled the co-optimization of resistance and virulence. These findings establish VexB as a molecular link between antimicrobial resistance and hypervirulence in pandemic V. cholerae, highlighting efflux pumps as dual-function therapeutic targets whose inhibition could both restore antibiotic activity and attenuate disease.

Animals↗