Universal masking during COVID-19 outbreaks in aged care settings: A systematic review and meta-analysis.

Aged care facilities (ACF) are a high-risk COVID-19 transmission setting, and older residents are at greater risk of severe outcomes. This systematic review and meta-analysis assessed whether universal masking and COVID-19 vaccination reduce SARS-CoV-2 attack rates (ARs) in ACF. Articles published between 1 December 2019 and 28 February 2022 were screened across five databases (Medline, Embase, PubMed, Scopus, Web of Science and Cumulative Index to Nursing and Allied Health Literature (CINAHL)). Risk of bias was assessed using relevant Joanna Briggs Institute critical appraisal tools. Meta-analysis of single proportions, subgroup analysis, and meta-regression were performed to compare the effects of universal masking and vaccine doses on pooled SARS-CoV-2 ARs. Of 99 included articles, SARS-CoV-2 ARs for residents were available in 86 studies (representing 139 outbreaks), and for staff in 49 studies (78 outbreaks). Universal masking was associated with lower SARS-CoV-2 ARs in ACF outbreaks (AR = 34.9% [95% CI: 27.2-42.6%]) compared to facilities without universal masking (67.3% [54.2-80.4%], p < .0001). In ACF with universal masking prior to outbreak onset, facility-wide testing, and documentation of asymptomatic infection, the asymptomatic AR at time of testing was 11.4% (6.5-17.4%) in residents. Receipt of zero, one and two vaccination doses were associated with ARs of 64.9% (49.6-80.2%), 54.9% (33.7-76.1%) and 45.2% (29.2-61.3%), respectively. To protect residents from COVID-19, ACF should provide vaccination of residents and staff, universal masking for staff, and facility-wide testing during times of heightened community transmission.

Policy Analysis for Prevention and Control of Influenza in Aged Care.

OBJECTIVE: This study aimed to analyze national influenza infection control policy documents within aged care settings by identifying the consistencies, inconsistencies, and gaps with the current evidence and by evaluating methodological quality. Aged care providers can use these findings to identify their policy documents' strengths and weaknesses. DESIGN: A quality and content analysis of national level policy documents. SETTING AND PARTICIPANTS: Aged care settings rely on national agencies' policy recommendations to control and prevent outbreaks. There is limited research on the effectiveness of control measures to prevent and treat influenza within aged care settings. Because of the complexities around aged care governance, the primary responsibility in developing a comprehensive facility-level, infection-prevention policy, falls to the providers. METHODS: The analysis was conducted using the (1) International Appraisal of Guidelines, Research and Evaluation assessment tool, containing 23 items across 6 domains; and the (2) Influenza Related Control Measures in Aged Care settings checklist, developed by the authors, with 82 recommendations covering: medical interventions, nonmedical interventions, and physical layout. RESULTS: There were 19 documents from 9 different high-income countries, with a moderately high methodological quality in general. The quality assessment's average score was 40.2% (95% CI 31.9%-44.7%). "Stakeholder involvement" ranked third, and "Editorial independence" and "Rigor of development" had the lowest average scores across all domains. The content analysis' average score was 37.2% (95% CI 10.5%-21.5%). The highest scoring document (59.1%) included term definitions, cited evidence for recommendations, and clear measurable instructions. "Physical Layout" had the least coverage and averaged 21.9% (95% CI 4.2%-37.5%), which shows a substantial gap in built environment recommendations. CONCLUSIONS AND IMPLICATIONS: Existing policy documents vary in their comprehensiveness. The higher scoring documents provide an ideal model for providers. The checklist tools can be used to assess and enhance documents. Further research on document end-user evaluation would be useful, as there is room for improvement in methodological quality and coverage of recommendation coverage, especially related to physical layout.

Serological Immunity to Smallpox in New South Wales, Australia.

The re-emergence of smallpox is an increasing and legitimate concern due to advances in synthetic biology. Vaccination programs against smallpox using the vaccinia virus vaccine ceased with the eradication of smallpox and, unlike many other countries, Australia did not use mass vaccinations. However, vaccinated migrants contribute to population immunity. Testing for vaccinia antibodies is not routinely performed in Australia, and few opportunities exist to estimate the level of residual population immunity against smallpox. Serological data on population immunity in Australia could inform management plans against a smallpox outbreak. Vaccinia antibodies were measured in 2003 in regular plasmapheresis donors at the Australian Red Cross Blood Service from New South Wales (NSW). The data were analysed to estimate the proportion of Australians in NSW with detectable serological immunity to vaccinia. The primary object of this study was to measure neutralising antibody titres against vaccinia virus. Titre levels in donor samples were determined by plaque reduction assay. To estimate current levels of immunity to smallpox infection, the decline in geometric mean titres (GMT) over time was projected using two values for the antibody levels estimated on the basis of different times since vaccination. The results of this study suggest that there is minimal residual immunity to the vaccinia virus in the Australian population. Although humoral immunity is protective against orthopoxvirus infections, cell-mediated immunity and immunological memory likely also play roles, which are not quantified by antibody levels. These data provide an immunological snapshot of the NSW population, which could inform emergency preparedness planning and outbreak control, especially concerning the stockpiling of vaccinia vaccine.

How Valid Are Assumptions About Re-emerging Smallpox? A Systematic Review of Parameters Used in Smallpox Mathematical Models.

Background: Globally eradicated in 1980, smallpox is listed as a category A bioterrorism agent. If smallpox were to re-emerge, it may be due to an act of bioterrorism or a laboratory accident, and the impact is likely to be severe. Preparedness against smallpox is subject to more uncertainty than other infectious diseases because it is eradicated, there is uncertainty about population immunity, and the current global health workforce has no practical experience or living memory of smallpox. In the event of re-emergence of smallpox, mathematical modeling plays a crucial role in improving the evidence base to inform preparedness, mitigation, and response activities. However, the predictions of mathematical models about outbreak magnitude and impact depend critically on the assumptions and disease parameters used. We aimed to identify modeling studies that would be applicable to re-emerging smallpox and to evaluate consistency and the certainty of the evidence published about the key parameters used. Methods: We conducted a systematic review using PRISMA criteria, of assumptions used in modeling studies on duration of latent, prodromal, and infectious period, as well as the choice of the basic reproduction number (R0) for re-emerging smallpox. We performed a literature search using PubMED, Scopus, Web of Science, and EMBASE and included peer-reviewed articles that focused on smallpox models, stated at least three of the aforementioned parameters and published in English. Findings: A total of 42 studies were selected for inclusion. There was general agreement on the duration of latent and prodromal periods, being 11-12 d (88%) and 3 d (59%), respectively. The duration of the infectious period varied from 4 to 20 d. Most models assumed 16 d (19%), 12 d (16.7%), and 8.6 d (12%) of infectiousness. In 25/34 studies, R0 ranged between 3 and 5, generally lower than the R0 calculated from past outbreaks. Discussion: Models of smallpox re-emergence also tend to use the same limited available historical data sources but assume a wide range of different estimates for key parameters. Models use very optimistic assumptions of decreased population immunity, despite high uncertainty about duration and magnitude of post-vaccination immunity. This review reveals a paradox. A substantial proportion of the modern population is unvaccinated, never exposed to boosting from wild-type smallpox, or immunocompromised; furthermore, vaccine-induced immunity wanes over time. Failure to consider these factors in a model will lead to underestimating the true impact of a re-emergent smallpox epidemic in the contemporary population.