RESUMEN
PURPOSE OF REVIEW: This review aims to discuss the current state of human infections with Avian Influenza A (H5) and (H9) viruses, to support awareness of the global epidemiology among clinicians and public health professionals interested in emerging respiratory infections. RECENT FINDINGS: Among increasing numbers of detections in avian species of Avian Influenza A(H5N1) clade 2.3.4.4b globally, reported human cases of severe infection have been rare.Enhanced surveillance of persons exposed to avian species infected with Influenza A(H5N1) clade 2.3.4.4b in different countries has identified small numbers of asymptomatic individuals with Avian Influenza A(H5N1) detected by PCR from the upper respiratory tract; some of these instances have been considered to represent contamination rather than infection.There have also been recent sporadic human cases of Avian Influenza A(H9N2) internationally, including in China and Cambodia. SUMMARY: Human infections with Avian Influenza A(H5) and (H9) viruses remain of interest as an emerging infection both to clinicians and public health professionals. While maintaining effective surveillance is essential, One health strategies to control infection in avian species will be key to mitigating these risks.
RESUMEN
Background: The Sanofi/GSK AS03-adjuvanted (VidPrevtyn Beta) vaccine and the Pfizer-BioNTech mRNA (Comirnaty Original/Omicron BA.4-5) bivalent vaccine were offered to adults aged 75 years and over in England from 3rd April 2023. This is the first time an adjuvanted COVID-19 vaccine has been administered as part of a UK COVID-19 vaccination programme. In clinical trials, antibody levels generated were comparable with mRNA vaccines but there are no real-world data on the effectiveness or duration of protection. Methods: We used a test-negative case-control study design to estimate the incremental vaccine effectiveness of the Sanofi/GSK and Pfizer bivalent BA.4-5 boosters against hospitalisation amongst those aged 75 years and older in England. Cases (those testing positive) and controls (those testing negative) were identified from the national COVID-19 PCR testing data undertaken in hospital settings. The study period included tests from 3rd April 2023 to 27th August 2023. Tests were linked to the COVID-19 vaccination register and to the national hospital admission database, restricting to those with an acute respiratory infection coded in the primary diagnosis field. Vaccine effectiveness was estimated using multivariable logistic regression amongst those who had last received an autumn 2022 booster given at least 3 months prior. The test result was the outcome and vaccination status the exposure. Analyses were adjusted for week of test, gender, age, clinical risk group status, care home resident status, region, index of multiple deprivation, ethnicity, influenza vaccination status and recent COVID-19 positivity. Findings: There were 14,169 eligible tests from hospitalised individuals aged 75 years and older; 3005 cases (positive tests) and 11,164 controls (negative tests). Effectiveness was highest in the period 9-13 days post vaccination for both manufacturers at about 50%; 43.7% (95% CI, 20.1-60.3%) and 56.1% (95% CI, 25.2-74.2%) for Sanofi/GSK and Pfizer BA.4-5, respectively. There was evidence of waning with a reduction to about 30% for both manufacturers after 5-9 weeks. The longest time interval post vaccination for which we were able to estimate effectiveness was 10+ weeks post vaccination, at which point vaccine effectiveness was 17.6% (95% CI, -3.6 to 34.5%) and 37.9% (95% CI, 13.2-55.5%) for the Sanofi/GSK and Pfizer BA.4-5 boosters, respectively. Interpretation: Both boosters provided good protection against hospitalisation amongst older adults. The finding that the adjuvanted vaccine targeting the distant Beta strain had similar effectiveness to the bivalent mRNA vaccine targeting more closely matched Omicron sub-lineages is notable and highlights the need for further real-world studies into the effectiveness of vaccines from different vaccine platforms and formulations in the presence of matched and unmatched strains. Funding: No external funding.
RESUMEN
Background: Since the first emergence of Omicron BA.1 in England in November 2021, numerous sub-lineages have evolved. In September 2022, BA.5 dominated. The prevalence of BQ.1 increased from October, while the prevalence of CH.1.1 and XBB.1.5 increased from December 2022 and January 2023, respectively. Little is known about the effectiveness of the vaccines against hospitalisation with these sub-lineages, nor the relative severity, so we here used national-level electronic health records from England to estimate vaccine effectiveness and variant severity. Methods: The study period for tests contributing to all analyses was from 5th December 2022 to 2nd April 2023, when the variants of interest were co-circulating. A test-negative case-control study was used to estimate the incremental effectiveness of the bivalent BA.1 booster vaccines against hospitalisation, relative to those with waned immunity where the last dose was at least 6 months prior. The odds of hospital admission for those testing PCR positive on the day of an attendance to accident and emergency departments and the odds of intensive care unit admission or death amongst COVID-19 admissions were compared between variants. Additionally, a Cox proportional hazards survival regression was used to investigate length of stay amongst hospitalised cases by variant. Findings: Our vaccine effectiveness study included 191,229 eligible tests with 1647 BQ.1 cases, 877 CH.1.1 cases, 1357 XBB.1.5 cases and 187,348 test negative controls. There was no difference in incremental vaccine effectiveness against hospitalisation with BQ.1, CH.1.1 or XBB.1.5, nor was there a difference in the severity of these variants. Effectiveness against hospitalisation was 48.0% (95% C.I.; 38.5-56.0%), 29.7% (95% C.I.; 7.5-46.6%) and 52.7% (95% C.I.; 24.6-70.4%) against BQ.1, CH.1.1 and XBB.1.5, respectively, at 5-9 weeks post booster vaccination. Compared to BQ.1, the odds of hospital admission were 0.87 (95% C.I.; 0.77-0.99) and 0.88 (95% C.I.; 0.75-1.02) for CH.1.1 and XBB.1.5 cases attending accident and emergency departments, respectively. There was no significant difference in the odds of admission to intensive care units or death for those with CH.1.1 (OR 0.96, 95% C.I.; 0.71-1.30) or XBB.1.5 (OR 0.67, 95% C.I.; 0.44-1.02) compared to BQ.1. There was also no significant difference in the length of hospital stay by variant. Interpretation: Together, these results provide reassuring evidence that the bivalent BA.1 booster vaccines provide similar protection against hospitalisation with BQ.1, CH.1.1 and XBB.1.5, and that the emergent CH.1.1 and XBB.1.5 sub-lineages do not cause more severe disease than BQ.1. Funding: None.
