Naturally Acquired Protection Against Upper Respiratory Symptoms Involving Group A Streptococcus in a Longitudinal Cohort Study

Streptococcus pyogenes Colonization in Children Aged 24-59 Months in the Gambia: Impact of Live Attenuated Influenza Vaccine and Associated Serological Responses

BACKGROUND

Immunity to Streptococcus pyogenes in high burden settings is poorly understood. We explored S. pyogenes nasopharyngeal colonization after intranasal live attenuated influenza vaccine (LAIV) among Gambian children aged 24-59 months, and resulting serological response to 7 antigens.

METHODS

A post hoc analysis was performed in 320 children randomized to receive LAIV at baseline (LAIV group) or not (control). S. pyogenes colonization was determined by quantitative polymerase chain reaction (qPCR) on nasopharyngeal swabs from baseline (day 0), day 7, and day 21. Anti-streptococcal IgG was quantified, including a subset with paired serum before/after S. pyogenes acquisition.

RESULTS

The point prevalence of S. pyogenes colonization was 7%-13%. In children negative at day 0, S. pyogenes was detected at day 7 or 21 in 18% of LAIV group and 11% of control group participants (P = .12). The odds ratio (OR) for colonization over time was significantly increased in the LAIV group (day 21 vs day 0 OR, 3.18; P = .003) but not in the control group (OR, 0.86; P = .79). The highest IgG increases following asymptomatic colonization were seen for M1 and SpyCEP proteins.

CONCLUSIONS

Asymptomatic S. pyogenes colonization appears modestly increased by LAIV, and may be immunologically significant. LAIV could be used to study influenza-S. pyogenes interactions. Clinical Trials Registration. NCT02972957.

Low rate of asymptomatic carriage and salivary immunoglobulin A response to Group A Streptococci in the healthy adult population in Finland

Streptococcus pyogenes, also called group A streptococcus (GAS), is a human pathogen causing a wide range of infections ranging from mild tonsillitis to severe, life threatening conditions such as bacteraemia, necrotizing fasciitis, and streptococcal toxic shock syndrome. GAS may also colonise the oropharynx without causing any signs of disease which is known as asymptomatic carriage. This study aims to investigate IgA responses against GAS and oral streptococci from saliva samples collected from healthy Finnish adults. In addition, asymptomatic throat GAS carriage was studied. The study participants consisted of healthy adult volunteers who provided one saliva sample, a throat swab, and a background questionnaire. Total salivary IgA, and GAS specific IgA were analysed from the saliva samples using enzyme-linked immunosorbent assays (ELISA) and the results were compared to oral streptococci specific IgA levels. Asymptomatic GAS throat carriers were identified by bacterial culture, and the isolates were emm typed. Samples from a total of 182 individuals were analysed. The median salivary IgA concentration was 62.9 µg/ml (range 17.3–649.9 µg/ml), and median GAS and oral streptococcal specific IgA concentrations 2.7 and 3.3 arbitrary units (AU, range 1.4–7.4 AU and 1.6–12.0 AU), respectively. Three individuals with asymptomatic GAS throat carriage were identified.

The global burden of sore throat and group A Streptococcus pharyngitis: A systematic review and meta-analysis

BACKGROUND

Contemporary data for the global burden of sore throat and group A Streptococcus (Strep A) pharyngitis are required to understand the frequency of disease and develop value propositions for Strep A vaccines.

METHODS

We used Clarivate Analytics' Web of Science platform to search WoS core collection, PubMed, Medline, data citation index, KCI-Korean Journal Database, Russian Science Citation Index, and the SciELO Citation Index for articles published between Jan 1, 2000, and Feb 15, 2021, from any country and in any language. The risk of bias was assessed using the JBI critical appraisal checklist. We used random-effects meta-analyses to pool sore throat and Strep A sore throat incidence rates from community-based studies. Our study was registered with PROSPERO (CRD42020181103).

FINDINGS

Of 5,529 articles identified by the search strategy, 26 studies met the inclusion criteria, but only two included data to determine incidence among adults. The pooled incidence rate, calculated for children only, was 82.2 episodes per 100 child-years (95% CI 25.2-286.3, I² = 100%) for sore throat (7 studies; 7,964 person years) and 22.1 episodes per 100 child-years (95% CI 14.7-33.1, I² = 98%) for Strep A sore throat (9 studies; 15,696 person years). The pooled cumulative incidence rate of sore throat from five studies was 31.9 per 100 children. There was significant methodological and statistical heterogeneity among studies, and five of 26 studies had a risk of bias score less than five (range: nine [maximum score] to one).

INTERPRETATION

Strep A sore throat has a considerable global burden. However, methodologically standardised studies are required to quantify that burden, analyse differences in rates between populations, and evaluate the likely impact of future Strep A vaccines.

FUNDING

This study was funded by Wellcome Trust 215,490/Z/19/Z.

Health-Economic Value of Vaccination Against Group A Streptococcus in the United States

BACKGROUND

Vaccines are needed to reduce the burden of group A Streptococcus (GAS). We assessed the potential health-economic value of GAS vaccines achievable through prevention of invasive disease and acute upper respiratory infections in the United States.

METHODS

We estimated annual incidence of invasive GAS disease and associated costs incurred from hospitalization and management of long-term sequelae, as well as productivity losses resulting from acute illness, long-term disability, and mortality. We also estimated healthcare and productivity costs associated with GAS pharyngitis, sinusitis, and acute otitis media. We estimated costs averted by prevention of invasive disease and acute upper respiratory infections for vaccines with differing efficacy profiles; our base case considered vaccines meeting the World Health Organization Preferred Product Profile (WHO-PPP) with a 6-year average duration of protection.

RESULTS

Costs of invasive GAS disease and acute upper respiratory infections totaled $6.08 (95% confidence interval [CI], $5.33-$6.86) billion annually. Direct effects of vaccines meeting WHO-PPP characteristics and administered at ages 12 and 18 months would avert $609 (95% CI, $558-$663) million in costs annually, primarily by preventing noninvasive disease; with an additional dose at age 5 years, averted costs would total $869 (95% CI, $798-$945) million annually. Adult vaccination at age 65 years would avert $326 (95% CI, $271-$387) million in annual costs associated with invasive GAS disease. Indirect effects of vaccination programs reducing incidence of GAS diseases across all ages by 20% would avert roughly $1 billion in costs each year.

CONCLUSIONS

The economic burden of GAS is substantial. Our findings should inform prioritization of GAS vaccine development and evaluation.

Incidence of Pharyngitis, Sinusitis, Acute Otitis Media, and Outpatient Antibiotic Prescribing Preventable by Vaccination Against Group A Streptococcus in the United States

BACKGROUND

Group A Streptococcus (GAS) is a leading cause of acute respiratory conditions that frequently result in antibiotic prescribing. Vaccines against GAS are currently in development.

METHODS

We estimated the incidence rates of healthcare visits and antibiotic prescribing for pharyngitis, sinusitis, and acute otitis media (AOM) in the United States using nationally representative surveys of outpatient care provision, supplemented by insurance claims data. We estimated the proportion of these episodes attributable to GAS and to GAS emm types included in a proposed 30-valent vaccine. We used these outputs to estimate the incidence rates of outpatient visits and antibiotic prescribing preventable by GAS vaccines with various efficacy profiles under infant and school-age dosing schedules.

RESULTS

GAS pharyngitis causes 19.1 (95% confidence interval [CI], 17.3-21.1) outpatient visits and 10.2 (95% CI, 9.0-11.5) antibiotic prescriptions per 1000 US persons aged 0-64 years, annually. GAS pharyngitis causes 93.2 (95% CI, 82.3-105.3) visits and 53.2 (95% CI, 45.2-62.5) antibiotic prescriptions per 1000 children ages 3-9 years, annually, representing 5.9% (95% CI, 5.1-7.0%) of all outpatient antibiotic prescribing in this age group. Collectively, GAS-attributable pharyngitis, sinusitis, and AOM cause 26.9 (95% CI, 23.9-30.8) outpatient visits and 16.1 (95% CI, 14.0-18.7) antibiotic prescriptions per 1000 population, annually. A 30-valent GAS vaccine meeting the World Health Organization's 80% efficacy target could prevent 5.4% (95% CI, 4.6-6.4%) of outpatient antibiotic prescriptions among children aged 3-9 years. If vaccine prevention of GAS pharyngitis made the routine antibiotic treatment of pharyngitis unnecessary, up to 17.1% (95% CI, 15.0-19.6%) of outpatient antibiotic prescriptions among children aged 3-9 years could be prevented.

CONCLUSIONS

An efficacious GAS vaccine could prevent substantial incidences of pharyngitis infections and associated antibiotic prescribing in the United States.