Prescribed burning is an effective land management tool that provides a range of benefits, including ecosystem restoration and wildfire risk reduction. However, prescribed fires, just like wildfires, introduce smoke that degrades air quality. Furthermore, while prescribed fires help manage wildfire risk, they do not eliminate the possibility of wildfires. It is therefore important to also evaluate fire and smoke impacts from wildfires that may occur after a prescribed burn. In this study, we developed a framework for understanding the air quality and health related trade-offs between wildfires and prescribed fires by simulating a set of counterfactual scenarios including wildfires, prescribed fires, and postprescribed burn wildfires. We applied this framework to the case of the Gatlinburg wildfire and found that emissions from prescribed burns and subsequent wildfire were slightly lower than those from the wildfire itself. This reduction resulted in lower daily average concentrations and exposures of PM(2.5), O(3), and NO(2). Even considering the possibility of a postprescribed burn wildfire, prescribed fires reduced population-weighted daily average PM(2.5), daily maximum 8-h average O(3), and 1-h maximum NO(2) concentrations. In Sevier County, Tennessee where the wildfire occurred, these reductions reached 5.28 μg/m(3), 0.18 ppb, and 1.68 ppb, respectively. The prescribed fires also reduced the person-days smoke exposures from the wildfire. Our results suggest that although prescribed fires cannot eliminate the air quality impacts of wildfires, they can greatly reduce smoke exposure in downwind areas distant from the burn sites.

Leptospirosis, an acute bacterial zoonotic disease, is endemic in Puerto Rico. Infection in approximately 10%-15% of patients with clinical disease progresses to severe, potentially fatal illness. Increased incidence has been associated with flooding in endemic areas around the world. In 2022, Hurricane Fiona, a Category 1 hurricane, made landfall and inundated Puerto Rico with heavy rainfall and severe flooding, increasing the risk for a leptospirosis outbreak. In response, the Puerto Rico Department of Health (PRDH) changed guidelines to make leptospirosis cases reportable within 24 hours, centralized the case investigation management system, and provided training and messaging to health care providers. To evaluate changes in risk for leptospirosis after Hurricane Fiona to that before the storm, the increase in cases was quantified, and patient characteristics and geographic distribution were compared. During the 15 weeks after Hurricane Fiona, 156 patients experienced signs and symptoms of leptospirosis and had a specimen with a positive laboratory result reported to PRDH. The mean weekly number of cases during this period was 10.4, which is 3.6 as high as the weekly number of cases during the previous 37 weeks (2.9). After Hurricane Fiona, the proportion of cases indicating exposure to potentially contaminated water increased from 11% to 35%, and the number of persons receiving testing increased; these factors likely led to the resulting overall surge in reported cases. Robust surveillance combined with outreach to health care providers after flooding events can improve leptospirosis case identification, inform clinicians considering early initiation of treatment, and guide public messaging to avoid wading, swimming, or any contact with potentially contaminated floodwaters.

Wearing a facemask can help to decrease the transmission of COVID-19. We investigated self-reported mask use among subjects aged 18 years and older participating in the COVID-19 Community Research Partnership (CRP), a prospective longitudinal COVID-19 surveillance study in the mid-Atlantic and southeastern United States. We included those participants who completed >=5 daily surveys each month from December 1, 2020 through August 31, 2021. Mask use was defined as self-reported use of a face mask or face covering on every interaction with others outside the household within a distance of less than 6 feet. Participants were considered vaccinated if they reported receiving >=1 COVID-19 vaccine dose. Participants (n=17,522) were 91% non-Hispanic White, 68% female, median age 57 years, 26% healthcare workers, with 95% self-reported receiving >=1 COVID-19 vaccine dose through August; mean daily survey response was 85%. Mask use was higher among vaccinated than unvaccinated participants across the study period, regardless of the month of the first dose. Mask use remained relatively stable from December 2020 through April (range 71-80% unvaccinated; 86-93% vaccinated) and declined in both groups beginning in mid-May 2021 to 34% and 42% respectively in June 2021; mask use has increased again since July 2021. Mask use by all was lower during weekends and on Christmas and Easter, regardless of vaccination status. Independent predictors of higher mask use were vaccination, age >=65 years, female sex, racial or ethnic minority group, and healthcare worker occupation, whereas a history of self-reported prior COVID-19 illness was associated with lower use. Copyright The copyright holder for this preprint is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. This article is a US Government work. It is not subject to copyright under 17 USC 105 and is also made available for use under a CC0 license.

Puerto Rico has experienced the full impact of the COVID-19 pandemic. Since SARS-CoV-2, the virus that causes COVID-19, was first detected on the island in March of 2020, it spread rapidly though the island’s population and became a critical threat to public health. We conducted a genomic surveillance study through a partnership with health agencies and academic institutions to understand the emergence and molecular epidemiology of the virus on the island. We sampled COVID-19 cases monthly over 19 months and sequenced a total of 753 SARS-CoV-2 genomes between March 2020 and September 2021 to reconstruct the local epidemic in a regional context using phylogenetic inference. Our analyses revealed that multiple importation events propelled the emergence and spread of the virus throughout the study period, including the introduction and spread of most SARS-CoV-2 variants detected world-wide. Lineage turnover cycles through various phases of the local epidemic were observed, where the predominant lineage was replaced by the next competing lineage or variant after approximately 4 months of circulation locally. We also identified the emergence of lineage B.1.588, an autochthonous lineage that predominated circulation in Puerto Rico from September to December 2020 and subsequently spread to the United States. The results of this collaborative approach highlight the importance of timely collection and analysis of SARS-CoV-2 genomic surveillance data to inform public health responses.

We reconstructed the SARS-CoV-2 epidemic caused by Omicron variant in Puerto Rico by sampling genomes collected during October 2021-May 2022. Our study revealed that Omicron BA.1 emerged and replaced Delta as the predominant variant in December 2021. Increased transmission rates and a dynamic landscape of Omicron sublineage infections followed.

Prior to the SARS-CoV-2 pandemic, antibiotic resistance was listed as the major global health care priority. Some analyses, including the O'Neill report, have predicted that deaths due to drug-resistant bacterial infections may eclipse the total number of cancer deaths by 2050. Although fungal infections remain in the shadow of public awareness, total attributable annual deaths are similar to, or exceeds, global mortalities due to malaria, tuberculosis or HIV. The impact of fungal infections has been exacerbated by the steady rise of antifungal drug resistant strains and species which reflects the widespread use of antifungals for prophylaxis and therapy, and in the case of azole resistance in Aspergillus, has been linked to the widespread agricultural use of antifungals. This review, based on a workshop hosted by the Medical Research Council and the University of Exeter, illuminates the problem of antifungal resistance and suggests how this growing threat might be mitigated.

BACKGROUND: Puerto Rico has experienced the full impact of the COVID-19 pandemic. Since SARS-CoV-2, the virus that causes COVID-19, was first detected on the island in March of 2020, it spread rapidly though the island's population and became a critical threat to public health. METHODS: We conducted a genomic surveillance study through a partnership with health agencies and academic institutions to understand the emergence and molecular epidemiology of the virus on the island. We sampled COVID-19 cases monthly over 19 months and sequenced a total of 753 SARS-CoV-2 genomes between March 2020 and September 2021 to reconstruct the local epidemic in a regional context using phylogenetic inference. RESULTS: Our analyses reveal that multiple importation events propelled the emergence and spread of the virus throughout the study period, including the introduction and spread of most SARS-CoV-2 variants detected world-wide. Lineage turnover cycles through various phases of the local epidemic were observed, where the predominant lineage was replaced by the next competing lineage or variant after ~4 months of circulation locally. We also identified the emergence of lineage B.1.588, an autochthonous lineage that predominated in Puerto Rico from September to December 2020 and subsequently spread to the United States. CONCLUSIONS: The results of this collaborative approach highlight the importance of timely collection and analysis of SARS-CoV-2 genomic surveillance data to inform public health responses.

Background: Particulate matter ≤10 μm in aerodynamic diameter (PM10) and diet quality are risk factors for systemic inflammation, which is associated with preterm birth (PTB). PM10 and a pro-inflammatory diet (assessed by the Dietary Inflammatory Index [DII®]) have been individually evaluated as causes of PTB and differences by offspring sex have been reported for the DII. However, additional studies are needed to evaluate joint effects of these associations to inform intervention efforts. Objectives: To evaluate the independent and joint effects of PM10 and energy-adjusted DII (E-DII) on PTB risks. Methods: PM10 estimates were generated from daily citywide averages for 1216 pregnant women from three subcohorts of the Early Life Exposures in Mexico to Environmental Toxicants study using data from the Mexico City Outdoor Air Monitoring Network. Among a subset of participants (N = 620), E-DII scores were calculated using a validated food frequency questionnaire. Cox Proportional Hazards models were run for select periods during pregnancy and entire pregnancy averages for E-DII and PM10. We assessed for potential non-linear associations using natural splines. Results: In adjusted models, PM10 exposure was associated with increased risks of PTB for a range of values (58–72 μg/m3) during the second trimester, while negative associations were seen during the second (≥74 μg/m3) and third trimesters (55–65 μg/m3). Analyses conducted using distributed lag models for periods closer to delivery (max lag = 90) did not show negative associations between PM10 exposure and preterm birth, and indeed positive significant associations were observed (estimates and figures). E-DII was not associated with PTB and there was no evidence of effect modification by infant sex. There was no evidence of interaction between PM10 and E-DII and the risk of preterm birth. Discussion: Associations between PM10 and PTB in Mexico City varied over time and across levels of PM10. Our findings of negative associations in the second and third trimesters, which are contrary to the hypothesized relationship between PM10 and PTB, may be due to a number of factors, including live birth bias and the exposure period evaluated. Differences in results for the periods evaluated suggest that PM10 from shorter exposure windows may play a more proximal role in initiating preterm labor.

Fine particulate matter (PM2.5) is a well-established risk factor for public health. To support both health risk assessment and epidemiological studies, data are needed on spatial and temporal patterns of PM2.5 exposures. This review article surveys publicly available exposure datasets for surface PM2.5 mass concentrations over the contiguous U.S., summarizes their applications and limitations, and provides suggestions on future research needs. The complex landscape of satellite instruments, model capabilities, monitor networks, and data synthesis methods offers opportunities for research development, but would benefit from guidance for new users. Guidance is provided to access publicly available PM2.5 datasets, to explain and compare different approaches for dataset generation, and to identify sources of uncertainties associated with various types of datasets. Three main sources used to create PM2.5 exposure data are: ground-based measurements (especially regulatory monitoring), satellite retrievals (especially aerosol optical depth, AOD), and atmospheric chemistry models. We find inconsistencies among several publicly available PM2.5 estimates, highlighting uncertainties in the exposure datasets that are often overlooked in health effects analyses. Major differences among PM2.5 estimates emerge from the choice of data (ground-based, satellite, and/or model), the spatiotemporal resolutions, and the algorithms used to fuse data sources.

Public Health Laboratories (PHLs) in Puerto Rico did not escape the devastation caused by Hurricane Maria. We implemented a quality management system (QMS) approach to systematically reestablish laboratory testing, after evaluating structural and functional damage. PHLs were inoperable immediately after the storm. Our QMS-based approach began in October 2017, ended in May 2018, and resulted in the reestablishment of 92% of baseline laboratory testing capacity. Here, we share lessons learned from the historic recovery of the largest United States' jurisdiction to lose its PHL capacity, and provide broadly applicable tools for other jurisdictions to enhance preparedness for public health emergencies.

Hurricane Maria made landfall in Puerto Rico on September 20, 2017, causing major damage to infrastructure and severely limiting access to potable water, electric power, transportation, and communications. Public services that were affected included operations of the Puerto Rico Department of Health (PRDOH), which provides critical laboratory testing and surveillance for diseases and other health hazards. PRDOH requested assistance from CDC for the restoration of laboratory infrastructure, surveillance capacity, and diagnostic testing for selected priority diseases, including influenza, rabies, leptospirosis, salmonellosis, and tuberculosis. PRDOH, CDC, and the Association of Public Health Laboratories (APHL) collaborated to conduct rapid needs assessments and, with assistance from the CDC Foundation, implement a temporary transport system for shipping samples from Puerto Rico to the continental United States for surveillance and diagnostic and confirmatory testing. This report describes the initial laboratory emergency response and engagement efforts among federal, state, and nongovernmental partners to reestablish public health laboratory services severely affected by Hurricane Maria. The implementation of a sample transport system allowed Puerto Rico to reinitiate priority infectious disease surveillance and laboratory testing for patient and public health interventions, while awaiting the rebuilding and reinstatement of PRDOH laboratory services.

OBJECTIVE: This study examines the impact of Family Healthware™ on communication behaviors; specifically, communication with family members and health care providers about family health history. METHODS: A total of 3786 participants were enrolled in the Family Healthware™ Impact Trial (FHITr) in the United States from 2005-7. The trial employed a two-arm cluster-randomized design, with primary care practices serving as the unit of randomization. Using generalized estimating equations (GEE), analyses focused on communication behaviors at 6month follow-up, adjusting for age, site and practice clustering. RESULTS: A significant interaction was observed between study arm and baseline communication status for the family communication outcomes (p's<.01), indicating that intervention had effects of different magnitude between those already communicating at baseline and those who were not. Among participants who were not communicating at baseline, intervention participants had higher odds of communicating with family members about family history risk (OR=1.24, p=0.042) and actively collecting family history information at follow-up (OR=2.67, p=0.026). Family Healthware™ did not have a significant effect on family communication among those already communicating at baseline, or on provider communication, regardless of baseline communication status. Greater communication was observed among those at increased familial risk for a greater number of diseases. CONCLUSION: Family Healthware™ prompted more communication about family history with family members, among those who were not previously communicating. Efforts are needed to identify approaches to encourage greater sharing of family history information, particularly with health care providers.

CONTEXT: Limited data exist about blood lead levels (BLLs) and potential exposures among children living in Puerto Rico. The Puerto Rico Department of Health has no formal blood lead surveillance program. OBJECTIVES: We assessed the prevalence of elevated BLLs (≥5 micrograms of lead per deciliter of blood), evaluated household environmental lead levels, and risk factors for BLL among children younger than 6 years of age living in Puerto Rico in 2010. METHODS: We used a population-based, cross-sectional sampling strategy to enroll an island-representative sample of Puerto Rican children younger than 6 years. We estimated the island-wide weighted prevalence of elevated BLLs and conducted bivariable and multivariable linear regression analyses to ascertain risk factors for elevated BLLs. RESULTS: The analytic data set included 355 households and 439 children younger than 6 years throughout Puerto Rico. The weighted geometric mean BLL of children younger than 6 years was 1.57 mug/dL (95% confidence interval [CI], 1.27-1.88). The weighted prevalence of children younger than 6 years with BLLs of 5 mug/dL or more was 3.18% (95% CI, 0.93-5.43) and for BLLs of 10 mug/dL or more was 0.50% (95% CI, 0-1.31). Higher mean BLLs were significantly associated with data collection during the summer months, a lead-related activity or hobby of anyone in the residence, and maternal education of less than 12 years. Few environmental lead hazards were identified. CONCLUSIONS: The prevalence of elevated BLLs among Puerto Rican children younger than 6 years is comparable with the most recent (2007-2010) US national estimate (BLLs ≥5 mug/dL = 2.6% [95% CI = 1.6-4.0]). Our findings suggest that targeted screening of specific higher-risk groups of children younger than 6 years can replace island-wide or insurance-specific policies of mandatory blood lead testing in Puerto Rico.

RATIONALE: Information on how ambient air pollution affects susceptible populations is needed to ensure protective air quality standards. OBJECTIVES: To estimate the effect of community-level ambient particulate matter (PM) and ozone (O(3)) on respiratory symptoms among primarily African-American and Latino, lower-income asthmatic children living in Detroit, Michigan and to evaluate factors associated with heterogeneity in observed health effects. METHODS: A cohort of 298 children with asthma was studied prospectively from 1999 to 2002. For 14 days each season over 11 seasons, children completed a respiratory symptom diary. Simultaneously, ambient pollutant concentrations were measured at two community-level monitoring sites. Logistic regression models using generalized estimating equations were fit for each respiratory symptom in single pollutant models, looking for interactions by area or by corticosteroid use, a marker of more severe asthma. Exposures of interest were: daily concentrations of PM<10mcm, <2.5mcm, and between 10 and 2.5mcm in aerodynamic diameter (PM(10), PM(2.5), and PM(10-2.5) respectively), the daily 8-hour maximum concentration of O(3) (8HrPeak), and the daily 1-hour maximum concentration of O(3) (1HrPeak). RESULTS: Outdoor PM(2.5), PM(10), 8HrPeak, and 1HrPeak O(3) concentrations were associated with increased odds of respiratory symptoms, particularly among children using corticosteroid medication and among children living in the southwest community of Detroit. Similar patterns of associations were not seen with PM(10-2.5). CONCLUSIONS: PM(2.5) and O(3) at levels near or below annual standard levels are associated with negative health impact in this population of asthmatic children. Variation in effects within the city of Detroit and among the subgroup using steroids emphasizes the importance of spatially refined exposure assessment and the need for further studies to elucidate mechanisms and effective risk reduction interventions.

AIM: To evaluate perceived risk, control, worry, and severity about diabetes, coronary heart disease (CHD) and stroke among individuals at increased familial risk of diabetes. METHODS: Data analyses were based on the Family Healthware Impact Trial. Baseline health beliefs were compared across three groups: (1) no family history of diabetes, CHD or stroke (n=836), (2) family history of diabetes alone (n=267), and (3) family history of diabetes and CHD and/or stroke (n=978). RESULTS: After adjusting for age, gender, race, education and BMI, scores for perceived risk for diabetes (p<0.0001), CHD (p<0.0001) and stroke (p<0.0001) were lowest in Group 1 and highest in Group 3. Similar results were observed about worry for diabetes (p<0.0001), CHD (p<0.0001) and stroke (p<0.0001). Perceptions of control or severity for diabetes, CHD or stroke did not vary across the three groups. CONCLUSIONS: Among individuals at increased familial risk for diabetes, having family members affected with CHD and/or stroke significantly influenced perceived risk and worry. Tailored lifestyle interventions for this group that assess health beliefs and emphasize approaches for preventing diabetes, as well as its vascular complications, may be an effective strategy for reducing the global burden of these serious but related chronic disorders.

SIV infection of natural host species such as sooty mangabeys results in high viral replication without clinical signs of simian AIDS. Studying such infections is useful for identifying immunologic parameters that lead to AIDS in HIV-infected patients. Here we have demonstrated that acute, SIV-induced CD4+ T cell depletion in sooty mangabeys does not result in immune dysfunction and progression to simian AIDS and that a population of CD3+CD4-CD8- T cells (double-negative T cells) partially compensates for CD4+ T cell function in these animals. Passaging plasma from an SIV-infected sooty mangabey with very few CD4+ T cells to SIV-negative animals resulted in rapid loss of CD4+ T cells. Nonetheless, all sooty mangabeys generated SIV-specific antibody and T cell responses and maintained normal levels of plasma lipopolysaccharide. Moreover, all CD4-low sooty mangabeys elicited a de novo immune response following influenza vaccination. Such preserved immune responses as well as the low levels of immune activation observed in these animals were associated with the presence of double-negative T cells capable of producing Th1, Th2, and Th17 cytokines. These studies indicate that SIV-infected sooty mangabeys do not appear to rely entirely on CD4+ T cells to maintain immunity and identify double-negative T cells as a potential subset of cells capable of performing CD4+ T cell-like helper functions upon SIV-induced CD4+ T cell depletion in this species.

Highly pathogenic avian influenza A virus (H5N1) has diverged antigenically and genetically since its initial detection in Asia in 1997. Viruses belonging to clade 2.2 in particular have been reported in numerous countries with the majority occurring in Egypt. Previous reports identified antigenic similarities between viruses belonging to clade 2.2. However, poultry and human viruses isolated in northern Egypt during 2007 and 2008 were found to be antigenically distinct from other clade 2.2 viruses from this country. Genetic analysis of the hemagglutinin revealed a high degree of nucleotide and amino acid divergence. The antigenic changes in Egyptian viruses isolated during 2007-08 necessitated that two of these strains be considered as potential H5N1 pre-pandemic vaccine candidates.

High pathogenicity avian influenza H5N1 has become an endemic poultry disease in several Asian countries, including Vietnam. Recently, clade 7 H5N1 viruses of the Eurasian lineage were isolated from chickens seized at ports of entry in Lang Son Province, Vietnam. Extensive nucleotide and amino acid divergence across the hemagglutinin (HA) protein gene of these isolates in comparison to previously described clade 7 viruses was identified. Clade 7 viruses are antigenically distinct from contemporary strains of H5N1 known to circulate in Vietnamese poultry (clade 1 and clade 2.3.4). Subsequent surveillance of sick poultry in live poultry markets in Hai Duong Province identified additional clade 7 isolates with HA genes very similar to the group B virus cluster detected previously at the Lang Son Province border. Antigenic analysis of the isolates from the live bird markets revealed significant cross-reactivity only between those clade 7 viruses belonging to the same subgroups. To meet pandemic response preparedness objectives, we have developed a reassortant virus from A/chicken/Vietnam/NCVD-016/2008, which could be used as a new prepandemic vaccine candidate for veterinary or human vaccination, should the need arise. Findings from these studies indicate that viruses with clade 7 HA have continued to evolve in Southeast Asian poultry, leading to significant antigenic drift relative to other H5N1 viruses currently circulating in Vietnam.

Acheson Louise S, Wang Catharine, Zyzanski Stephen J, Lynn Audrey, Ruffin Mack T, Gramling Robert, Rubinstein Wendy S, O'Neill Suzanne M, Nease Donald E, . Genetics in medicine : official journal of the American College of Medical Genetics 2010 12(4) 212-8

CONTEXT: Family history is a risk factor for many common chronic diseases, yet it remains underutilized in primary care practice. BACKGROUND: Family Healthware is a self-administered, web-based tool that assesses familial risk for CHD; stroke; diabetes; and colorectal, breast, and ovarian cancer, and provides a personalized prevention plan based on familial risk. The Family Healthware Impact Trial evaluated the tool. DESIGN: In this cluster RCT, participants completed baseline and 6-month follow-up surveys. The intervention group used Family Healthware directly after the baseline survey. Controls used the tool after completing the follow-up survey. SETTING/PARTICIPANTS: Patients aged 35-65 years with no known diagnosis of these six diseases were enrolled from 41 primary care practices. MAIN OUTCOME MEASURES: The prevalence of family-history-based risk for coronary heart disease (CHD); stroke; diabetes; and colorectal, breast, and ovarian cancer was determined in a primary care population. RESULTS: From 2005 to 2007, 3786 participants enrolled. Data analysis was undertaken from September 2007 to March 2008. Participants had a mean age of 50.6 years and were primarily white (91%) women (70%). Of the 3585 participants who completed the risk assessment tool, 82% had a strong or moderate familial risk for at least one of the diseases: CHD (strong=33%, moderate=26%); stroke (strong=15%, moderate=34%); diabetes (strong=11%, moderate=26%); colorectal cancer (strong=3%, moderate=11%); breast cancer (strong=10%, moderate=12%); and ovarian cancer (strong=4%, moderate=6%). Women had a significantly (p<0.04) higher familial risk than men for all diseases except colorectal and ovarian cancer. Overweight participants were significantly (p<or=0.02) more likely to have a strong family history for CHD, stroke, and diabetes. Older participants were significantly (p<or=0.02) more likely to report a strong family history for CHD and stroke as well as colorectal and breast cancer. CONCLUSIONS: This self-administered, online tool delineated a substantial burden of family-history-based risk for these chronic diseases in an adult, primary care population. TRIAL REGISTRATION: NCT00164658.

BACKGROUND: Highly pathogenic H5N1 avian influenza viruses currently circulating in birds have caused hundreds of human infections, and pose a significant pandemic threat. Vaccines are a major component of the public health preparedness for this likely event. The rapid evolution of H5N1 viruses has resulted in the emergence of multiple clades with distinct antigenic characteristics that require clade-specific vaccines. A variant H5N1 virus termed clade 2.3.4 emerged in 2005 and has caused multiple fatal infections. Vaccine candidates that match the antigenic properties of variant viruses are necessary because inactivated influenza vaccines elicit strain-specific protection. OBJECTIVE: To address the need for a suitable seed for manufacturing a clade 2.3.4 vaccine, we developed a new H5N1 pre-pandemic candidate vaccine by reverse genetics and evaluated its safety and replication in vitro and in vivo. METHODS: A reassortant virus termed, Anhui/PR8, was produced by reverse genetics in compliance with WHO pandemic vaccine development guidelines and contains six genes from A/Puerto Rico/8/34 as well as the neuraminidase and hemagglutinin (HA) genomic segments from the A/Anhui/01/2005 virus. The multi-basic cleavage site of HA was removed to reduce virulence. RESULTS: The reassortant Anhui/PR8 grows well in eggs and is avirulent to chicken and ferrets but retains the antigenicity of the parental A/Anhui/01/2005 virus. CONCLUSION: These results indicate that the Anhui/PR8 reassortant lost a major virulent determinant and it is suitable for its use in vaccine manufacturing and as a reference vaccine virus against the H5N1 clade 2.3.4 viruses circulating in eastern China, Vietnam, Thailand, and Laos.

Vaccination will be a critical public health intervention to mitigate the next influenza pandemic. Its effectiveness will depend on preparedness at multiple levels, from the laboratory bench to the population. Here we describe a global approach to ensure that appropriate candidate vaccine viruses are produced, evaluated, and made available to vaccine manufacturers in a timely fashion. This is an integrated activity involving global virologic and epidemiologic surveillance, genetic and antigenic characterization of influenza viruses, pandemic risk assessments, selection of appropriate virus strains for vaccines, production of reassortant viruses by reverse genetics, and finally, analysis of their safety and growth characteristics prior to distribution. These procedures must comply with national and international regulations governing vaccine and environmental safety.