The Advisory Committee on Immunization Practices' Updated Interim Recommendation for Allocation of COVID-19 Vaccine - United States, December 2020.

The first vaccines for prevention of coronavirus disease 2019 (COVID-19) in the United States were authorized for emergency use by the Food and Drug Administration (FDA) (1) and recommended by the Advisory Committee on Immunization Practices (ACIP) in December 2020.* However, demand for COVID-19 vaccines is expected to exceed supply during the first months of the national COVID-19 vaccination program. ACIP advises CDC on population groups and circumstances for vaccine use.† On December 1, ACIP recommended that 1) health care personnel§ and 2) residents of long-term care facilities¶ be offered COVID-19 vaccination first, in Phase 1a of the vaccination program (2). On December 20, 2020, ACIP recommended that in Phase 1b, vaccine should be offered to persons aged ≥75 years and frontline essential workers (non-health care workers), and that in Phase 1c, persons aged 65-74 years, persons aged 16-64 years with high-risk medical conditions, and essential workers not recommended for vaccination in Phase 1b should be offered vaccine.** These recommendations for phased allocation provide guidance for federal, state, and local jurisdictions while vaccine supply is limited. In its deliberations, ACIP considered scientific evidence regarding COVID-19 epidemiology, ethical principles, and vaccination program implementation considerations. ACIP's recommendations for COVID-19 vaccine allocation are interim and might be updated based on changes in conditions of FDA Emergency Use Authorization, FDA authorization for new COVID-19 vaccines, changes in vaccine supply, or changes in COVID-19 epidemiology.

The Advisory Committee on Immunization Practices' Interim Recommendation for Use of Pfizer-BioNTech COVID-19 Vaccine in Adolescents Aged 12-15 Years - United States, May 2021.

The Pfizer-BioNTech COVID-19 (BNT162b2) vaccine is a lipid nanoparticle-formulated, nucleoside-modified mRNA vaccine encoding the prefusion spike glycoprotein of SARS-CoV-2, the virus that causes COVID-19. Vaccination with the Pfizer-BioNTech COVID-19 vaccine consists of 2 intramuscular doses (30 µg, 0.3 mL each) administered 3 weeks apart. On December 11, 2020, the Food and Drug Administration (FDA) issued an Emergency Use Authorization (EUA) for use of the Pfizer-BioNTech COVID-19 vaccine (Pfizer, Inc; Philadelphia, Pennsylvania) in persons aged ≥16 years (1); on December 12, 2020, the Advisory Committee on Immunization Practices (ACIP) issued an interim recommendation for use of the vaccine in the same age group (2). As of May 12, 2021, approximately 141.6 million doses of the Pfizer-BioNTech COVID-19 vaccine had been administered to persons aged ≥16 years.* On May 10, 2021, FDA expanded the EUA for the Pfizer-BioNTech COVID-19 vaccine to include adolescents aged 12-15 years (1). On May 12, 2021, ACIP issued an interim recommendation† for use of the Pfizer-BioNTech COVID-19 vaccine in adolescents aged 12-15 years for the prevention of COVID-19. To guide its deliberations regarding the vaccine, ACIP used the Evidence to Recommendation (EtR) Framework,§ using the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach.¶ The ACIP recommendation for the use of the Pfizer-BioNTech COVID-19 vaccine in persons aged ≥12 years under an EUA is interim and will be updated as additional information becomes available.

The Advisory Committee on Immunization Practices' Interim Recommendation for Use of Pfizer-BioNTech COVID-19 Vaccine in Children Aged 5-11 Years - United States, November 2021.

The Pfizer-BioNTech COVID-19 (BNT162b2) vaccine is a lipid nanoparticle-formulated, nucleoside-modified mRNA vaccine encoding the prefusion spike glycoprotein of SARS-CoV-2, the virus that causes COVID-19. On August 23, 2021, the Food and Drug Administration (FDA) approved a Biologics License Application (BLA) for use of the Pfizer-BioNTech COVID-19 vaccine, marketed as Comirnaty (Pfizer, Inc.), in persons aged ≥16 years (1). The Pfizer-BioNTech COVID-19 vaccine is also recommended for adolescents aged 12-15 years under an Emergency Use Authorization (EUA) (1). All persons aged ≥12 years are recommended to receive 2 doses (30 µg, 0.3 mL each), administered 3 weeks apart (2,3). As of November 2, 2021, approximately 248 million doses of the Pfizer-BioNTech COVID-19 vaccine had been administered to persons aged ≥12 years in the United States.* On October 29, 2021, FDA issued an EUA amendment for a new formulation of Pfizer-BioNTech COVID-19 vaccine for use in children aged 5-11 years, administered as 2 doses (10 µg, 0.2 mL each), 3 weeks apart (Table) (1). On November 2, 2021, the Advisory Committee on Immunization Practices (ACIP) issued an interim recommendation† for use of the Pfizer-BioNTech COVID-19 vaccine in children aged 5-11 years for the prevention of COVID-19. To guide its deliberations regarding recommendations for the vaccine, ACIP used the Evidence to Recommendation (EtR) Framework§ and incorporated a Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach.¶ The ACIP recommendation for the use of the Pfizer-BioNTech COVID-19 vaccine in children aged 5-11 years under an EUA is interim and will be updated as additional information becomes available. The Pfizer-BioNTech COVID-19 vaccine has high efficacy (>90%) against COVID-19 in children aged 5-11 years, and ACIP determined benefits outweigh risks for vaccination. Vaccination is important to protect children against COVID-19 and reduce community transmission of SARS-CoV-2.

The Advisory Committee on Immunization Practices' Interim Recommendation for Use of Moderna COVID-19 Vaccine - United States, December 2020.

On December 18, 2020, the Food and Drug Administration (FDA) issued an Emergency Use Authorization (EUA) for the Moderna COVID-19 (mRNA-1273) vaccine (ModernaTX, Inc; Cambridge, Massachusetts), a lipid nanoparticle-encapsulated, nucleoside-modified mRNA vaccine encoding the stabilized prefusion spike glycoprotein of SARS-CoV-2, the virus that causes coronavirus disease 2019 (COVID-19) (1). This vaccine is the second COVID-19 vaccine authorized under an EUA for the prevention of COVID-19 in the United States (2). Vaccination with the Moderna COVID-19 vaccine consists of 2 doses (100 µg, 0.5 mL each) administered intramuscularly, 1 month (4 weeks) apart. On December 19, 2020, the Advisory Committee on Immunization Practices (ACIP) issued an interim recommendation* for use of the Moderna COVID-19 vaccine in persons aged ≥18 years for the prevention of COVID-19. To guide its deliberations regarding the vaccine, ACIP employed the Evidence to Recommendation (EtR) Framework,† using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach.§ Use of all COVID-19 vaccines authorized under an EUA, including the Moderna COVID-19 vaccine, should be implemented in conjunction with ACIP's interim recommendations for allocating initial supplies of COVID-19 vaccines (3). The ACIP recommendation for the use of the Moderna COVID-19 vaccine under EUA is interim and will be updated as additional information becomes available.

The Advisory Committee on Immunization Practices' Interim Recommendations for Additional Primary and Booster Doses of COVID-19 Vaccines - United States, 2021.

Three COVID-19 vaccines are currently approved under a Biologics License Application (BLA) or authorized under an Emergency Use Authorization (EUA) by the Food and Drug Administration (FDA) and recommended for primary vaccination by the Advisory Committee on Immunization Practices (ACIP) in the United States: the 2-dose mRNA-based Pfizer-BioNTech/Comirnaty and Moderna COVID-19 vaccines and the single-dose adenovirus vector-based Janssen (Johnson & Johnson) COVID-19 vaccine (1,2) (Box 1). In August 2021, FDA amended the EUAs for the two mRNA COVID-19 vaccines to allow for an additional primary dose in certain immunocompromised recipients of an initial mRNA COVID-19 vaccination series (1). During September-October 2021, FDA amended the EUAs to allow for a COVID-19 vaccine booster dose following a primary mRNA COVID-19 vaccination series in certain recipients aged ≥18 years who are at increased risk for serious complications of COVID-19 or exposure to SARS-CoV-2 (the virus that causes COVID-19), as well as in recipients aged ≥18 years of Janssen COVID-19 vaccine (1) (Table). For the purposes of these recommendations, an additional primary (hereafter additional) dose refers to a dose of vaccine administered to persons who likely did not mount a protective immune response after initial vaccination. A booster dose refers to a dose of vaccine administered to enhance or restore protection by the primary vaccination, which might have waned over time. Health care professionals play a critical role in COVID-19 vaccination efforts, including for primary, additional, and booster vaccination, particularly to protect patients who are at increased risk for severe illness and death.

The Advisory Committee on Immunization Practices' Ethical Principles for Allocating Initial Supplies of COVID-19 Vaccine - United States, 2020.

To reduce the spread of SARS-CoV-2, the virus that causes coronavirus disease 2019 (COVID-19) and its associated impacts on health and society, COVID-19 vaccines are essential. The U.S. government is working to produce and deliver safe and effective COVID-19 vaccines for the entire U.S. population. The Advisory Committee on Immunization Practices (ACIP)* has broadly outlined its approach for developing recommendations for the use of each COVID-19 vaccine authorized or approved by the Food and Drug Administration (FDA) for Emergency Use Authorization or licensure (1). ACIP's recommendation process includes an explicit and transparent evidence-based method for assessing a vaccine's safety and efficacy as well as consideration of other factors, including implementation (2). Because the initial supply of vaccine will likely be limited, ACIP will also recommend which groups should receive the earliest allocations of vaccine. The ACIP COVID-19 Vaccines Work Group and consultants with expertise in ethics and health equity considered external expert committee reports and published literature and deliberated the ethical issues associated with COVID-19 vaccine allocation decisions. The purpose of this report is to describe the four ethical principles that will assist ACIP in formulating recommendations for the allocation of COVID-19 vaccine while supply is limited, in addition to scientific data and implementation feasibility: 1) maximize benefits and minimize harms; 2) promote justice; 3) mitigate health inequities; and 4) promote transparency. These principles can also aid state, tribal, local, and territorial public health authorities as they develop vaccine implementation strategies within their own communities based on ACIP recommendations.

The Advisory Committee on Immunization Practices' Interim Recommendation for Allocating Initial Supplies of COVID-19 Vaccine - United States, 2020.

The emergence of SARS-CoV-2, the virus that causes coronavirus disease 2019 (COVID-19), has led to a global pandemic that has disrupted all sectors of society. Less than 1 year after the SARS-CoV-2 genome was first sequenced, an application* for Emergency Use Authorization for a candidate vaccine has been filed with the Food and Drug Administration (FDA). However, even if one or more vaccine candidates receive authorization for emergency use, demand for COVID-19 vaccine is expected to exceed supply during the first months of the national vaccination program. The Advisory Committee on Immunization Practices (ACIP) advises CDC on population groups and circumstances for vaccine use.† ACIP convened on December 1, 2020, in advance of the completion of FDA's review of the Emergency Use Authorization application, to provide interim guidance to federal, state, and local jurisdictions on allocation of initial doses of COVID-19 vaccine. ACIP recommended that, when a COVID-19 vaccine is authorized by FDA and recommended by ACIP, both 1) health care personnel§ and 2) residents of long-term care facilities (LTCFs)¶ be offered vaccination in the initial phase of the COVID-19 vaccination program (Phase 1a**).†† In its deliberations, ACIP considered scientific evidence of SARS-CoV-2 epidemiology, vaccination program implementation, and ethical principles.§§ The interim recommendation might be updated over the coming weeks based on additional safety and efficacy data from phase III clinical trials and conditions of FDA Emergency Use Authorization.

The Advisory Committee on Immunization Practices' Interim Recommendation for Use of Pfizer-BioNTech COVID-19 Vaccine - United States, December 2020.

On December 11, 2020, the Food and Drug Administration (FDA) issued an Emergency Use Authorization (EUA) for the Pfizer-BioNTech COVID-19 (BNT162b2) vaccine (Pfizer, Inc; Philadelphia, Pennsylvania), a lipid nanoparticle-formulated, nucleoside-modified mRNA vaccine encoding the prefusion spike glycoprotein of SARS-CoV-2, the virus that causes coronavirus disease 2019 (COVID-19) (1). Vaccination with the Pfizer-BioNTech COVID-19 vaccine consists of 2 doses (30 µg, 0.3 mL each) administered intramuscularly, 3 weeks apart. On December 12, 2020, the Advisory Committee on Immunization Practices (ACIP) issued an interim recommendation* for use of the Pfizer-BioNTech COVID-19 vaccine in persons aged ≥16 years for the prevention of COVID-19. To guide its deliberations regarding the vaccine, ACIP employed the Evidence to Recommendation (EtR) Framework,† using the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach.§ The recommendation for the Pfizer-BioNTech COVID-19 vaccine should be implemented in conjunction with ACIP's interim recommendation for allocating initial supplies of COVID-19 vaccines (2). The ACIP recommendation for the use of the Pfizer-BioNTech COVID-19 vaccine under EUA is interim and will be updated as additional information becomes available.

Use of antiviral drugs to reduce household transmission of pandemic (H1N1) 2009, United Kingdom.

The United Kingdom implemented a containment strategy for pandemic (H1N1) 2009 through administering antiviral agents (AVs) to patients and their close contacts. This observational household cohort study describes the effect of AVs on household transmission. We followed 285 confirmed primary cases in 259 households with 761 contacts. At 2 weeks, the confirmed secondary attack rate (SAR) was 8.1% (62/761) and significantly higher in persons <16 years of age than in those >50 years of age (18.9% vs. 1.2%, p<0.001). Early (<48 hours) treatment of primary case-patients reduced SAR (4.5% vs. 10.6%, p = 0.003). The SAR in child contacts was 33.3% (10/30) when the primary contact was a woman and 2.9% (1/34) when the primary contact was a man (p = 0.010). Of 53 confirmed secondary case-patients, 45 had not received AV prophylaxis. The effectiveness of AV prophylaxis in preventing infection was 92%.

Transmission of rabies virus from an organ donor to four transplant recipients.

BACKGROUND: In 2004, four recipients of kidneys, a liver, and an arterial segment from a common organ donor died of encephalitis of an unknown cause. METHODS: We reviewed the medical records of the organ donor and the recipients. Blood, cerebrospinal fluid, and tissues from the recipients were tested with a variety of assays and pathological stains for numerous causes of encephalitis. Samples from the recipients were also inoculated into mice. RESULTS: The organ donor had been healthy before having a subarachnoid hemorrhage that led to his death. Encephalitis developed in all four recipients within 30 days after transplantation and was accompanied by rapid neurologic deterioration characterized by agitated delirium, seizures, respiratory failure, and coma. They died an average of 13 days after the onset of neurologic symptoms. Mice inoculated with samples from the affected patients became ill seven to eight days later, and electron microscopy of central nervous system (CNS) tissue demonstrated rhabdovirus particles. Rabies-specific immunohistochemical and direct fluorescence antibody staining demonstrated rabies virus in multiple tissues from all recipients. Cytoplasmic inclusions consistent with Negri bodies were seen in CNS tissue from all recipients. Antibodies against rabies virus were present in three of the four recipients and the donor. The donor had told others of being bitten by a bat. CONCLUSIONS: This report documenting the transmission of rabies virus from an organ donor to multiple recipients underscores the challenges of preventing and detecting transmission of unusual pathogens through transplantation.

Transmission of West Nile virus through blood transfusion in the United States in 2002.

BACKGROUND: During the 2002 West Nile virus epidemic in the United States, patients were identified whose West Nile virus illness was temporally associated with the receipt of transfused blood and blood components. METHODS: Patients with laboratory evidence of recent West Nile virus infection within four weeks after receipt of a blood component from a donor with viremia were considered to have a confirmed transfusion-related infection. We interviewed the donors of these components, asking them whether they had had symptoms compatible with the presence of a viral illness before or after their donation; blood specimens retained from the time of donation and collected at follow-up were tested for West Nile virus. RESULTS: Twenty-three patients were confirmed to have acquired West Nile virus through transfused leukoreduced and nonleukoreduced red cells, platelets, or fresh-frozen plasma. Of the 23 recipients, 10 (43 percent) were immunocompromised owing to transplantation or cancer and 8 (35 percent) were at least 70 years of age. Immunocompromised recipients tended to have longer incubation periods than nonimmunocompromised recipients and infected persons in mosquito-borne community outbreaks. Sixteen donors with evidence of viremia at donation were linked to the 23 infected recipients; of these donors, 9 reported viral symptoms before or after donation, 5 were asymptomatic, and 2 were lost to follow-up. Fever, new rash, and painful eyes were independently associated with being an implicated donor with viremia rather than a donor without viremia. All 16 donors were negative for West Nile virus-specific IgM antibody at donation. CONCLUSIONS: Transfused red cells, platelets, and fresh-frozen plasma can transmit West Nile virus. Screening of potential donors with the use of nucleic acid-based assays for West Nile virus may reduce this risk.

Transmission of West Nile virus from an organ donor to four transplant recipients.

BACKGROUND: In August 2002, fever and mental-status changes developed in recipients of organs from a common donor. Transmission of West Nile virus through organ transplantation was suspected. METHODS: We reviewed medical records, conducted interviews, and collected blood and tissue samples for testing with a variety of assays. Persons who donated blood to the organ donor and associated blood components were identified and tested for West Nile virus. RESULTS: We identified West Nile virus infection in the organ donor and in all four organ recipients. Encephalitis developed in three of the organ recipients, and febrile illness developed in one. Three recipients became seropositive for West Nile virus IgM antibody; the fourth recipient had brain tissue that was positive for West Nile virus by isolation and nucleic acid and antigen assays. Serum specimens obtained from the organ donor before and immediately after blood transfusions showed no evidence of West Nile virus; however, serum and plasma samples obtained at the time of organ recovery were positive on viral nucleic acid testing and viral culture. The organ donor had received blood transfusions from 63 donors. A review of blood donors and follow-up testing identified one donor who had viremia at the time of donation and who became seropositive for West Nile virus IgM antibodies during the next two months. CONCLUSIONS: Our investigation of this cluster documents the transmission of West Nile virus by organ transplantation. Organ recipients receiving immunosuppressive drugs may be at high risk for severe disease after West Nile virus infection. Blood transfusion was the probable source of the West Nile virus viremia in the organ donor.

The advisory committee on immunization practices' interim recommendation for use of Pfizer-Biontech Covid-19 vaccine in children aged 5­11 years: United States, november 2021

The Pfizer-BioNTech COVID-19 (BNT162b2) vaccine is a lipid nanoparticle­formulated, nucleoside-modified mRNA vaccine encoding the prefusion spike glycoprotein of SARS-CoV-2, the virus that causes COVID-19. On August 23, 2021, the Food and Drug Administration (FDA) approved a Biologics License Application (BLA) for use of the Pfizer-BioNTech COVID-19 vaccine, marketed as Comirnaty (Pfizer, Inc.), in persons aged ≥16 years (1). The Pfizer-BioNTech COVID-19 vaccine is also recommended for adolescents aged 12­15 years under an Emergency Use Authorization (EUA) (1). All persons aged ≥12 years are recommended to receive 2 doses (30 µg, 0.3 mL each), administered 3 weeks apart (2,3). As of November 2, 2021, approximately 248 million doses of the Pfizer-BioNTech COVID-19 vaccine had been administered to persons aged ≥12 years in the United States.* On October 29, 2021, FDA issued an EUA amendment for a new formulation of Pfizer-BioNTech COVID-19 vaccine for use in children aged 5­11 years, administered as 2 doses (10 µg, 0.2 mL each), 3 weeks apart (Table) (1). On November 2, 2021, the Advisory Committee on Immunization Practices (ACIP) issued an interim recommendation† for use of the Pfizer-BioNTech COVID-19 vaccine in children aged 5­11 years for the prevention of COVID-19. To guide its deliberations regarding recommendations for the vaccine, ACIP used the Evidence to Recommendation (EtR) Framework§ and incorporated a Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach.¶ The ACIP recommendation for the use of the Pfizer-BioNTech COVID-19 vaccine in children aged 5­11 years under an EUA is interim and will be updated as additional information becomes available. The Pfizer-BioNTech COVID-19 vaccine has high efficacy (>90%) against COVID-19 in children aged 5­11 years, and ACIP determined benefits outweigh risks for vaccination. Vaccination is important to protect children against COVID-19 and reduce community transmission of SARS-CoV-2.

Emerging infectious agents: do they pose a risk to the safety of transfused blood and blood products?

The blood supply is safer than it has been at any other time in recent history, and, in the context of other health care-related adverse events, the risks associated with blood transfusion are extremely small. The current high level of safety is the result of successive refinements and improvements in how blood is collected, tested, processed, and transfused; nonetheless, blood and plasma products remain vulnerable to newly identified or reemerging infections. In recent years, numerous infectious agents-including several newly discovered hepatitis viruses, the agents of transmissible spongiform encephalopathies, and tickborne pathogens-have been identified as potential threats to the safety of blood and plasma. Continued vigilance is critical to protect the blood supply from known pathogens and to monitor for the emergence of new infectious agents. Recent terrorist activities in the United States add new considerations to maintaining the safety and supply of blood. Education of clinicians and patients regarding the benefits and risks associated with the judicious use of blood and blood products can assist in informed decision making.

Tuberculin skin testing surveillance of health care personnel.

To estimate the incidence of and assess risk factors for occupational Mycobacterium tuberculosis transmission to health care personnel (HCP) in 5 New York City and Boston health care facilities, performance of prospective tuberculin skin tests (TSTs) was conducted from April 1994 through October 1995. Two-step testing was used at the enrollment of 2198 HCP with negative TST results. Follow-up visits were scheduled for every 6 months. Thirty (1.5%) of 1960 HCP with >/=1 follow-up evaluation had TST conversion (that is, an increase in TST induration of >/=10 mm). Independent risk factors for TST conversion were entering the United States after 1991 and inclusion in a tuberculosis-contact investigation in the workplace. These findings suggest that occupational transmission of M. tuberculosis occurred, as well as possible nonoccupational transmission or late boosting among foreign-born HCP who recently entered the United States. These results demonstrate the difficulty in interpreting TST results and estimating conversion rates among HCP, especially when large proportions of foreign-born HCP are included in surveillance.

A comprehensive approach to percutaneous injury prevention during phlebotomy: results of a multicenter study, 1993-1995.

OBJECTIVE: To examine a comprehensive approach for preventing percutaneous injuries associated with phlebotomy procedures. DESIGN AND SETTING: From 1993 through 1995, personnel at 10 university-affiliated hospitals enhanced surveillance and assessed underreporting of percutaneous injuries; selected, implemented, and evaluated the efficacy of phlebotomy devices with safety features (ie, engineered sharps injury prevention devices [ESIPDs]); and assessed healthcare worker satisfaction with ESIPDs. Investigators also evaluated the preventability of a subset of percutaneous injuries and conducted an audit of sharps disposal containers to quantify activation rates for devices with safety features. RESULTS: The three selected phlebotomy devices with safety features reduced percutaneous injury rates compared with conventional devices. Activation rates varied according to ease of use, healthcare worker preference for ESIPDs, perceived "patient adverse events," and device-specific training. CONCLUSIONS: Device-specific features and healthcare worker training and involvement in the selection of ESIPDs affect the activation rates for ESIPDs and therefore their efficacy. The implementation of ESIPDs is a useful measure in a comprehensive program to reduce percutaneous injuries associated with phlebotomy procedures.

Anthrax and the mail: the making of an educational video for mail workers.

The anthrax bioterrorist attacks in 2001 affected millions of people who process, sort, and deliver mail. To more effectively communicate information intended to protect the health of these workers, the Centers for Disease Control and Prevention produced a short-format educational video in December 2001 that targets this diverse group. This report illustrates how an educational video can be rapidly produced to translate and disseminate public health recommendations as part of a public health emergency response.

The use of masks and respirators to prevent transmission of influenza: a systematic review of the scientific evidence.

There are limited data on the use of masks and respirators to reduce transmission of influenza. A systematic review was undertaken to help inform pandemic influenza guidance in the United Kingdom. The initial review was performed in November 2009 and updated in June 2010 and January 2011. Inclusion criteria included randomised controlled trials and quasi-experimental and observational studies of humans published in English with an outcome of laboratory-confirmed or clinically-diagnosed influenza and other viral respiratory infections. There were 17 eligible studies. Six of eight randomised controlled trials found no significant differences between control and intervention groups (masks with or without hand hygiene; N95/P2 respirators). One household trial found that mask wearing coupled with hand sanitiser use reduced secondary transmission of upper respiratory infection/influenza-like illness/laboratory-confirmed influenza compared with education; hand sanitiser alone resulted in no reduction. One hospital-based trial found a lower rate of clinical respiratory illness associated with non-fit-tested N95 respirator use compared with medical masks. Eight of nine retrospective observational studies found that mask and/or respirator use was independently associated with a reduced risk of severe acute respiratory syndrome (SARS). Findings, however, may not be applicable to influenza and many studies were suboptimal. None of the studies established a conclusive relationship between mask/respirator use and protection against influenza infection. Some evidence suggests that mask use is best undertaken as part of a package of personal protection especially hand hygiene. The effectiveness of masks and respirators is likely linked to early, consistent and correct usage.

Epidemiologic and virologic assessment of the 2009 influenza A (H1N1) pandemic on selected temperate countries in the Southern Hemisphere: Argentina, Australia, Chile, New Zealand and South Africa.

UNLABELLED: INTRODUCTION AND SETTING: Our analysis compares the most comprehensive epidemiologic and virologic surveillance data compiled to date for laboratory-confirmed H1N1pdm patients between 1 April 2009 - 31 January 2010 from five temperate countries in the Southern Hemisphere-Argentina, Australia, Chile, New Zealand, and South Africa. OBJECTIVE: We evaluate transmission dynamics, indicators of severity, and describe the co-circulation of H1N1pdm with seasonal influenza viruses. RESULTS: In the five countries, H1N1pdm became the predominant influenza strain within weeks of initial detection. South Africa was unique, first experiencing a seasonal H3N2 wave, followed by a distinct H1N1pdm wave. Compared with the 2007 and 2008 influenza seasons, the peak of influenza-like illness (ILI) activity in four of the five countries was 3-6 times higher with peak ILI consultation rates ranging from 35/1,000 consultations/week in Australia to 275/100,000 population/week in New Zealand. Transmission was similar in all countries with the reproductive rate ranging from 1.2-1.6. The median age of patients in all countries increased with increasing severity of disease, 4-14% of all hospitalized cases required critical care, and 26-68% of fatal patients were reported to have ≥1 chronic medical condition. Compared with seasonal influenza, there was a notable downward shift in age among severe cases with the highest population-based hospitalization rates among children <5 years old. National population-based mortality rates ranged from 0.8-1.5/100,000. CONCLUSIONS: The difficulty experienced in tracking the progress of the pandemic globally, estimating its severity early on, and comparing information across countries argues for improved routine surveillance and standardization of investigative approaches and data reporting methods.