Assessing evidence for avian-to-human transmission of influenza A/H9N2 virus in rural farming communities in northern Vietnam.

Rural farming communities in northern Vietnam do not routinely practice vaccination for influenza A viruses (IAV) for either humans or poultry, which enables us to study transmission intensity via seroepidemiology. Using samples from a longitudinal cohort of farming households, we determined the number of symptomatic and asymptomatic human infections for seasonal IAV and avian A/H9 over 2 years. As expected, we detected virologically confirmed acute cases of seasonal IAV in humans, as well as large numbers of subclinical seroconversions to A/H1pdm [55/265 (21 %)], A/H3 [95/265 (36 %)] and A/H9 [24/265 (9 %)]. Five of the A/H9 human seroconverters likely represented true infections rather than heterosubtypic immunity, because the individuals seroconverted solely to A/H9. Among co-located poultry, we found significantly higher seroprevalance for A/H5 compared to A/H9 in both chickens and ducks [for northern study sites overall, 337/1105 (30.5 %) seropositive for A/H5 and 123/1105 (11.1 %) seropositive for A/H9].

Protection against COVID-19 hospitalisation conferred by primary-series vaccination with AZD1222 in non-boosted individuals: first vaccine effectiveness results of the European COVIDRIVE study and meta-regression analysis.

Background: Vaccine effectiveness (VE) studies with long-term follow-up are needed to understand durability of protection against severe COVID-19 outcomes conferred by primary-series vaccination in individuals not receiving boosters. COVIDRIVE is a European public-private partnership evaluating brand-specific vaccine effectiveness (VE). We report a prespecified interim analysis of primary-series AZD1222 (ChAdOx1 nCoV-19) VE. Methods: Seven Study Contributors in Europe collected data on individuals aged ≥18 years who were hospitalised with severe acute respiratory infection (June 1st, 2021-September 5th, 2022) and eligible for COVID-19 vaccination prior to hospitalisation. In this test-negative case-control study, individuals were defined as test-positive cases or test-negative controls (SARS-CoV-2 RT-PCR) and were either fully vaccinated (two AZD1222 doses, 4-12 weeks apart, completed ≥14 days prior to symptom onset; no booster doses) or unvaccinated (no COVID-19 vaccine prior to hospitalisation). The primary objective was to estimate AZD1222 VE against COVID-19 hospitalisation. A literature review and meta-regression were conducted to contextualise findings on durability of protection. Findings: 761 individuals were included during the 15-month analysis period. Overall AZD1222 VE estimate was 72.8% (95% CI, 53.4-84.1). VE was 93.8% (48.6-99.3) in participants who received second AZD1222 doses ≤8 weeks prior to hospitalisation, with spline-based VE estimates demonstrating protection (VE ≥ 50%) 30 weeks post-second dose. Meta-regression analysis (data from seven publications) showed consistent results, with ≥80% protection against COVID-19 hospitalisation through ∼43 weeks post-second dose, with some degree of waning. Interpretation: Primary-series AZD1222 vaccination confers protection against COVID-19 hospitalisation with enduring levels of VE through ≥6 months. Funding: AstraZeneca.

Media portrayal of vaccine: a content analysis of Vietnam online news about a pentavalent vaccine in the Expanded Program of Immunization.

Background: Vaccine hesitancy has become a prominent public health concern, particularly within the coronavirus disease 2019 (COVID-19) pandemic context. Worries about vaccine side effects are often cited as a reason for hesitancy, while media reporting about this topic plays an important role in influencing the public's perspectives about vaccines and vaccination. In Vietnam, during 2012-2013, there were several adverse events following immunization (AEFIs) of Quinvaxem- a pentavalent vaccine in the Expanded Immunization Program, which made big headlines in the media. Such incidences have contributed to changes in vaccination policies and influenced parents' concerns to date. This study explores the portrayal of Quinvaxem in Vietnam digital news during four periods marked by important events. Methods: We performed quantitative and qualitative analysis with a coding framework to identify main content focus, sentiments towards Quinvaxem, and emotional tones in these articles. Results: In total, we included 360 articles into analysis. The amount of news coverage about Quinvaxem increased after AEFIs happened, from 7 articles before AEFIs to 98 and 159 articles in the following periods when AEFIs and investigation into vaccine safety occurred. Most articles are neutral in titles (n=255/360) and content (n=215/360) towards Quinvaxem and do not convey emotional expressions (n=271/360). However, articles focusing on side effects contain negative sentiments and emotional expressions more frequently than articles of other contents while AEFIs details were conflicting across articles. Vaccine sentiments are provoked in the information about vaccine quality and safety, health authority, local delivery, and quoted vaccine opinions. Emotion-conveying elements in 89/360 articles included emotional wording and imagery and expressive punctuation. Conclusions: The heterogeneity of information in online news may reinforce uncertainty about vaccine safety and decrease vaccine intention. Our results have important implications for vaccine communication, given the current plan of the Vietnamese government to roll out COVID-19 vaccination to younger children.