When influenza season arrives, conventional morbidity and mortality statistics, health care encounters, and laboratory data might not “fully reflect the disruption caused to the social and economic life of the community,” say CDC researchers. That is the reason that the National Institute for Occupational Safety and Health (NIOSH) monitors health-related workplace absenteeism every month, and why the World Health Organization (WHO) uses those data to help determine the impact of influenza season worldwide.
The workplace is a prime area for transmission—people share workspace and equipment and interact with one another closely. Estimates of influenza attack rates for working-aged adults can be as high as 14.3% in a given influenza season, the CDC says.
According to NIOSH, absenteeism rose sharply in the 2017-2018 season, to a level significantly higher than that of the average during the previous 5 seasons. In October, 1.7% of workers were absent due to health issues. That figure began climbing in November, peaking in January at 3.0%, significantly exceeding the epidemic threshold. Absenteeism declined steadily after that to a low of 1.4%, then began rising again in August and September.
Male workers, people aged 45 to 64 years, and those working in certain occupations (including management, business, and repair services) were more likely to be out.
Regional absenteeism peaks corresponded to concurrent peaks in influenza-like illness (ILI) activity in those regions. The researchers say this is in line with a longtime recognition that health-related workplace absenteeism correlates well with the presence of ILI, which is why absenteeism data are used as a nonspecific indicator of ILI in the community. During the 2009-2010 influenza A (H1N1) pandemic, for instance, peak workplace absenteeism correlated with the highest occurrence of both ILI and influenza-positive laboratory tests, according to NIOSH.
The associations between ILI, absenteeism, and demographic characteristics are complex, the researchers say, and mediated by factors such as vaccination coverage and access to paid sick leave.
The usual recommendations—vaccination, covering coughs and sneezes, handwashing, and routinely cleaning frequently touched surfaces—are the most effective ways to prevent transmission, the researchers note. During a pandemic, other measures may be needed, such as “social distancing” in workplaces.
NIOSH makes absenteeism surveillance results available ( https://www.cdc.gov/niosh/topics/absences/default.html). The researchers suggest that employers might wish to consult them when developing prevention messages.