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NIOSH Activities: 2009 H1N1 Influenza-related Health Hazard Evaluations

The 2009-2010 influenza season saw the emergence of the 2009 H1N1 influenza (flu) virus which caused the first influenza pandemic (global outbreak of disease caused by a new flu virus) in more than 40 years. During this period NIOSH conducted several health hazard evaluations to assess workplace exposures to flu. These reports identified ways of reducing risks to workers during the 2009-2010 influenza pandemic. Guidance and recommendations in these reports may be applicable to current and future influenza seasons.

General Description: The NIOSH HHE Program examined flu vaccination coverage and attitudes and beliefs about vaccination among school district employees. Investigators surveyed 412 of 841 school district employees. Of the respondents, 58% reported getting the flu vaccine for the 2012-2013 flu season. Most employees reported getting the flu vaccine at the school district central office. Investigators found that employees who had positive attitudes and perceptions about the flu vaccine and those who had received the flu vaccine the year before were more likely to have been vaccinated. The most common reasons for not getting the flu vaccine were beliefs that employees did not need the vaccine, that the vaccine did not work, and that the employees did not have time to get vaccinated. One hundred twenty responding employees reported influenza-like illness symptoms between August 2012 and March 2013. Of these, 92 reported working while feeling sick. The two most common reasons cited for working while sick were “I have a professional obligation to my students” and “I did not think I was contagious or could make other people sick”. HHE Program investigators recommended that the employer work with local vaccine providers to offer the flu vaccine to employees at each of the schools. Investigators recommended that the employer educate employees about the flu and the flu vaccine, emphasizing employees’ risk of infection, vaccine effectiveness, and vaccine safety. Employees were encouraged to get the flu vaccine, stay informed, and get information about the flu and the flu vaccine from reliable sources. Investigators recommended that employees not go to work when ill with flu-like symptoms, which include fever, cough, and sore throat.

Status: Influenza vaccination coverage among school employees: assessing knowledge, attitudes, and behaviors; de Perio-MA; Wiegand-DM; Brueck-SE; J Sch Health 2014 Sep; 84(9): 586-592,

Status: This NIOSH HHE final report was published in January 2014. A complete copy of the final NIOSH HHE report may be obtained at

Point of Contact: CDC-INFO

General Description: NIOSH provided technical assistance to the California Occupational Safety and Health Administration. NIOSH was asked to evaluate whether there were any defects in the N95 NIOSH certified respirators obtained from the California Department of Public Health respirator stockpile. The concern arose following the identification of N95 respiratory fit testing failures for 60–100% of the healthcare workers fit tested by a large healthcare organization. NIOSH did not evaluate the California healthcare organization’s fit testing program or conduct additional fit testing on the healthcare workers who failed the California fit tests.

Relevance to worker safety and health: The purpose of this evaluation was to determine if the fit test pass rate reported by a California healthcare organization’s facilities was due to defects in the N95 respirators. The evaluation aimed to determine if this resulted in non-compliance with the NIOSH requirements for air filtration and airflow (breathing) resistance. The performance tests and review of manufacturing quality assurance records and inspections revealed compliance with applicable approval requirements for the N95 respirators. The evaluation did not identify a need for any further actions. A description of the five-part assessment and the complete findings are presented in the final report available below.

Status: This NIOSH HHE final report was published in May 2010. A complete copy of the final report may be obtained at

Point of Contact: CDC-INFO

General Description: In August 2009, NIOSH received a request for assistance in classifying and managing the occupational exposure risk of transportation security employees to 2009 H1N1 influenza. The evaluation consisted of reviewing the Transportation Security Administration (TSA) H1N1 influenza guidance on protecting its workerforce and interviewing agency occupational safety and health management. The medium exposure risk category (i.e., employees with high-frequency contact with the general population) previously identified by the TSA and the selected PPE made available to the employees were determined to be appropriate. Actions taken by TSA for the medium risk category agreed with current Department of Homeland Security (DHS), Centers for Disease Control and Prevention (CDC), and Occupational Safety and Health Administration (OSHA) pandemic influenza guidance.

Relevance to Worker Safety and Health: This NIOSH HHE addressed the appropriateness of the risk category identified by the agency for its transportation security employees using the OSHA “Occupational Risk Pyramid for Pandemic Influenza” [OSHA 2009].

Status: This NIOSH HHE was closed in January 2010 with an informational letterCdc-pdf

Link: Guidance on Preparing Workplaces for an Influenza PandemicCdc-pdfExternal

Point of Contact: CDC-INFO

General Description: NIOSH provided technical assistance evaluating vaccination rates for seasonal and 2009 H1N1 influenza among workers at child care centers in an Ohio county. NIOSH investigators surveyed employees of 32 randomly selected licensed child care centers about personal and work characteristics, pertinent medical history, receipt of or intention to receive the 2009 H1N1 and seasonal influenza vaccines, and knowledge about and attitudes towards each vaccine. Of 403 invited child care employees, 384 (95%) completed a survey. Forty-five (12%) respondents reported having received the pH1N1 vaccine. Eighty-five (22%) respondents reported having received the seasonal influenza vaccine. The most common reason for receiving either vaccine was to protect oneself or one’s family. For both vaccines, among unvaccinated respondents, 19% reported that they intended to get the vaccine, and 81% reported that they did not intend to do so. Misconceptions about the need for the vaccines and the efficacy and safety of the vaccines were the most common reasons cited for not receiving either vaccine. NIOSH recommended that efforts to improve vaccination rates among child care providers include notification of vaccination campaigns through media and public health messages addressing the most frequent antivaccination ideas. NIOSH also recommended educational interventions in the form of training that focused on child care providers’ risk for infection, the efficacy and safety profile of the vaccine, and providers’ responsibility to get vaccinated. Furthermore, NIOSH suggested that employers consider requiring influenza vaccination for their employees as part of a comprehensive influenza prevention program.

Relevance to worker safety and health: This NIOSH HHE concerned the extent to which child care workers were knowledgeable and capable of protecting themselves from seasonal and 2009 H1N1 influenza infections in the daycare setting. Measures that can be implemented to correct identified problems are listed in the final report of the evaluation.

Status: This NIOSH HHE final report was published in February 2011. A complete copy of the final report may be obtained at:

A peer-reviewed journal article from this evaluation is available: Low influenza vaccination rates among child care workers in the United States: assessing knowledge, attitudes, and behaviors. J Community Health 2012 Apr; 37(2):272-281.

Point of Contact: CDC-INFO

General Description: NIOSH received requests for health hazard evaluations at two separate dental offices in a metropolitan area of Ohio. Management at each dental office was concerned about transmission of 2009 H1N1 influenza virus to dental staff. Both offices wanted to participate in a workplace exposure assessment of influenza virus transmission. NIOSH investigators visited each dental practice four separate times over a 6-week period beginning in January 2010. During each site visit, NIOSH collected air and surface samples for pH1N1 and seasonal influenza virus. NIOSH found that exposure of dental staff to H1N1 and seasonal influenza viruses at both practices during the sampling days appears to have been limited, which might have been related to the low number of patients reporting ILI and an incidence of community influenza below typical seasonal influenza levels. NIOSH also found that seasonal and H1N1 influenza vaccination rates among dental staff were very low. NIOSH recommend that all employees get the seasonal influenza vaccine every year and should self-assess for influenza symptoms and not report to work if ill. NIOSH also recommended that dental practices consider developing mechanisms to screen patients for ILI symptoms prior to their visits or at the time of check-in and advise patients to consider postponing visits and procedures that are not urgent until 24 hours after the patient is free of fever, especially in times of high influenza activity within the community.

Relevance to worker safety and health: This NIOSH HHE represented an opportunity to characterize the exposure of dental staff to 2009 H1N1 influenza virus. Dental staff may be at increased risk of exposure to influenza virus through their close work with the public.

Status: Field work for this HHE is complete. This NIOSH HHE final report was published in January 2011. A complete copy of the final report may be obtained at:

Point of Contact: CDC-INFO

General Description: NIOSH received a request from employees of a hospital in Alaska concerning an attendance policy instituted in November 2008. The employees believed that the leave policy encouraged employees to come to work when they were ill and remain at work when they were experiencing symptoms. They were specifically concerned about the employee leave policy conflicting with CDC guidelines concerning 2009 H1N1 influenza and sick leave [ Note: This website is now an archival page, no longer maintained. Reader is referred to:]. NIOSH provided the employees with guidelines on policies for employee compensation and sick leave during the HINI influenza outbreak and other pandemics.

Relevance to Worker Safety and Health: To reduce the likelihood that employees avoid bringing illness into the workplace and are able to attend appropriately to their illness, employers should establish non-punitive workplace policies regarding reporting of illness and sick leave.

Status: This NIOSH HHECdc-pdfExternal was closed with an informational letter.

Point of Contact: CDC-INFO

Page last reviewed: March 28, 2018