Preventing Influenza in the Health Care Setting

Infection Control Today, Volume 26, Issue 8

Because of mask-wearing and social distancing, numbers of influenza cases have been down the last 2 years. However, experts say numbers this year could go back up to numbers in prior years. The public and health care workers alike need a nudge to get vaccinated.

Since COVID-19 is here to stay, are health care workers apathetic to the effect of influenza? The last 2 flu seasons were “rather aberrant,” says William Schaffner, MD, medical director of the National Foundation for Infectious Diseases, said in an interview with Infection Control Today®(ICT®). “Two years ago, there was no flu. Well, that was because we were all locked up. Children are the great spreaders of the influenza virus in our population, and they were all at home.”

Schaffner continued, “Last year, we had an influenza season that started up in December and [went] into early January as though it were going to be a moderately severe season. And then the bottom fell out! Influenza just plummeted and then, surprisingly, it lingered for a long time, and we were getting cases of flu beyond April and into May. So we’ve had 2 aberrant seasons, both of them less impactful than usual.”

Two milder-than-usual flu seasons, plus a population worn out with relentless worries about COVID-19, may have created an apathetic attitude about flu for some individuals. “Recent memory on the part of the general public is a little bit dim on influenza now,” Schaffner said. “We’re going to have to remind them that this is also an illness that we have to take seriously.”

The public may not be the only ones who need a refresher course. Although health care workers seem to be more aware of the importance of influenza prevention thanks to the COVID-19 pandemic, “they have expressed high levels of frustration, burnout, and fatigue with interventions which can lead to subsequent challenges with implementation,” Kate Grusich, a public affairs specialist for the Centers for Disease Control and Prevention (CDC), said in an interview with ICT®.

However, she added, “The pandemic has highlighted the role of core infection prevention and control (IPC) practices like hand hygiene and environmental disinfection and led to renewed efforts to improve these practices.” The last few years have been extremely instructive. “Lessons learned about the importance of ‘source control’ is one specific example that will likely continue to pay dividends for prevention efforts for other respiratory viruses, including influenza viruses,” she said.

Influenza in a medical institution “has a different epidemiology and effects compared to influenza in the community,” causing more complications and mortality, warn investigators for the Transgovernmental Enterprise for Pandemic Influenza in Korea, who published a guideline on flu prevention and control in health care settings.1

Roughly 0.3 to 0.8 cases of flu occur per 100 hospitalized patients, the researchers say. When an outbreak happens in a health care institution, the attack rate increases to 0.7% to 20%, and can rise to more than 30% in the ward where the outbreak began. In a long-term care facility with many elderly patients, they add, the attack rate can leap to 70%. The risk gets higher for the staff, too, of course, with an attack rate of 11% to 59%.1

However, the study authors cite research that found when “aggressive” infection control measures were used, such as vaccination, reporting and monitoring respiratory symptoms, and “exclusion from work” for the symptomatic, the attack rate for health care workers was maintained at less than 2%.1

The key is to cast a wide protective net. Preventing the spread of pathogens, like influenza viruses, in health care settings depends on implementing sets of interventions to “build redundancy” and improve effectiveness, Grusich says. Interventions like early recognition of patients with acute respiratory illness who might have influenza and the use of recommended personal protective equipment are important. She says the use of facemasks by symptomatic patients for source control, although recommended as part of standard precautions for people with respiratory symptoms for years, is also an important intervention that has been used for COVID-19 patients in health care settings, and should be applied to all patients with respiratory symptoms in health care settings.

The Occupational Safety and Health Administration (OSHA) recommends, among other things, encouraging sick workers to stay home; using airborne infection isolation rooms; making sure HVAC systems in patient rooms, procedure rooms, and examination rooms are functioning properly; and limiting the transport of infectious patients throughout the facility (instead, conduct exams and procedures at the bedside). However, OSHA warns, pandemic flu is always a concern for health care employers, and advises that a pandemic flu plan “should be based on a ‘worst-case’ scenario.”2

As Grusich indicates, it’s not a matter of simply covering bases but covering them using redundant measures. The “cornerstone of influenza prevention,” she said, is annual vaccination. Here again, COVID-19 has stolen nearly all attention. That’s one reason Schaffner is concerned. “[In] the fall of 2021, as we were starting to vaccinate for influenza, there had been so much attention [given] to [the] COVID-19 vaccine that I had to reintroduce the notion of influenza to [individuals] and remind them [it] was another nasty respiratory virus [for] which we have vaccine. And I felt I was starting from scratch,” he said.

Certainly, the steps people took to prevent COVID also helped prevent flu. And Grusich noted only slight reductions exist in the estimated percentages of children and adults who received the influenza vaccine this past season compared with the 2020-2021 season. “However, the estimated percentage of pregnant [individuals] who received [an] influenza vaccine during this past season was substantially lower than [in] the [previous] 2 seasons,” she said, adding the reasons for lower influenza vaccination coverage in children, pregnant individuals, and nonpregnant adults are unknown.

“Despite best efforts, flu vaccination in the US has remained under 50% for most seasons, although it has slowly been rising.”3

Why do some individuals not get vaccinated against influenza? Schaffner said a myth he’d like to dispel is the idea “that because we do not have a perfect match between the vaccine and the circulating virus, the influenza vaccine’s not good. ‘We don’t need to get it.’ That’s a very dangerous concept. Even [if] there’s not a good match, there’s often sufficient protection so the recipient is protected against the most serious aspects of influenza.” These aspects include hospitalization, intensive care unit admission, and death.

For health care workers specifically, he said, “By getting the vaccine, we are not only protecting ourselves—it’s a patient safety issue. We don’t want to give our infection to our patients! It’s important that we do everything as a professional and ethical responsibility to prevent the transmission of our virus to our patients.”

According to results of a CDC survey of 2,391 health care personnel, 76% of health care workers reported getting flu shots in the 2020-21 season. That was fewer than the previous season (81%), although not statistically significant. Vaccine coverage was highest among those working in hospitals (92%) and lowest among workers in long-term care facilities (66%).4

“One of the things that accelerated change in hospitals and large health care systems was the vaccine became mandatory,” Schaffner said. “And that concept has not been embraced in the long-term care industry. I think because there’s so much turnover in personnel, industry leaders are concerned [whether] they’ll have enough [staff] working if they insist on vaccination. That’s what I keep hearing.”

The CDC survey results showed physicians, nurses, and pharmacists had the highest coverage (91.3%, 90.3%, and 90.3%, respectively). Interestingly, receipt of a COVID-19 vaccine was the second strongest factor correlated with higher influenza vaccination coverage. Also interesting: 10.5% of respondents said they got vaccinated “to reduce flu’s impact on the health care system during the COVID-19 pandemic.”

Vaccination coverage was lowest among health care workers whose employers neither required nor recommended vaccination. “Before mandates, there were clear distinctions among [individuals] depending upon their professional background. Pharmacists were the best vaccinated. Over time, the doctors [were] second, but the nurses were always in third place. The literature is full of this. Nurses express more concern for one reason or another about vaccination, which is a matter of double concern because our nurses have the most contact with patients. You would want them to be vaccine advocates rather than vaccine cautious,” Schaffner said.

The main reasons health care workers gave for not getting a flu shot were “I do not need the vaccination” (17%), “I might experience side effects or get sick from the vaccine” (12%), and “I don’t think the vaccination is effective in preventing flu” (12%).

“Some health care providers don’t like needles. Some are concerned the vaccine isn’t good. They’re concerned about—and this is not trivial—side effects. Well, [most individuals] who get [the] influenza vaccine may have a sore arm for a few hours or a day, but it’s unusual. And [if] we look at experience, we don’t have a big spike in absenteeism for reasons of side effects when we get these vaccines,” Schaffner said.

But physical adverse effects are not the only thing worrying health care workers. Schaffner said they may be concerned about “adverse effects in the sense that if they’re not working, they won’t get paid. There are lots of single health care workers out there, and [for] single moms, that’s a real threat to their home economics. And there [are], among younger women who are health care providers, lingering concerns about reproductive issues. Of course, influenza vaccine is recommended for [anyone] who’s pregnant.

Research has shown that workplace vaccination promotions, such as on-site clinics, can boost vaccination numbers. Convenience can be one of the best-selling points for flu vaccination, because economic concerns include not wanting to come in on an unpaid day to get the vaccine. “You can’t penalize people for getting vaccinated,” Schaffner says. “You have to provide the vaccine during work time.” That means also for the people who work at night or on weekends. “You may actually have to, in certain circumstances, bring the vaccine to them.”

What’s next?

In the CDC survey, most of the respondents (up to 87%) agreed or strongly agreed with statements such as “Flu vaccine is safe” and “If I get a flu vaccine, people around me would be protected.” Positive attitudes toward the safety and effectiveness of the vaccine were strongly associated with higher vaccination coverage. On the other hand, approximately half of health care workers disagreed with the statement that “flu is a serious threat to their health.”

The flu virus is notoriously mutable, providing new challenges every year. Can we know—or guess—what this coming flu season will be like? “The CDC long ago discovered that predicting flu was a very [iffy] business, Schaffner says. “So I won’t predict that but I will tell you that in Australia, they’ve had a fairly brisk influenza season. It doesn’t always predict what will happen during our winter, but it is a cautionary note. So if we needed another reason to be vaccinated, there it is. We don’t know what comes, so we hope for the better and prepare for the worst. And preparing for the worst is, ‘let’s all get vaccinated.’”


Baek JH, Seo YB, Choi WS, et al. Guideline on the prevention and control of seasonal influenza in healthcare setting. Korean J Intern Med. 2014;29(2):265-280. doi:10.3904/kjim.2014.29.2.265

Occupational Safety and Health Administration. United States Department of Labor. Employer guidance reducing healthcare workers’ exposures to seasonal flu virus. Accessed Aug. 15, 2022.

USAFacts. US coronavirus vaccine tracker. website. Updated August 3, 2022. Accessed Aug. 15, 2022.

Centers for Disease Control and Prevention. Influenza vaccination coverage among health care personnel — United States, 2020-21 influenza season. Updated October 7, 2021. Accessed Aug. 15, 2022.