Influenza Vaccination Information for Health Care Workers

Did You Know?

• CDC, the Advisory Committee on Immunization Practices (ACIP), and the Healthcare Infection Control Practices Advisory Committee (HICPAC) recommend that all U.S. health care workers get vaccinated annually against influenza.
• Health care workers include (but are not limited to) physicians, nurses, nursing assistants, therapists, technicians, emergency medical service personnel, dental personnel, pharmacists, laboratory personnel, autopsy personnel, students and trainees, contractual staff not employed by the health-care facility, and persons (e.g., clerical, dietary, housekeeping, laundry, security, maintenance, administrative, billing, and volunteers) not directly involved in patient care but potentially exposed to infectious agents that can be transmitted to and from health care workers and patients.

How Many Health Care Workers Got Vaccinated Last Season?

• 2019-2020 flu vaccination coverage among health care personnel (HCP) was 80.6%, similar to coverage during the past five seasons (77.3% -81.1%).
  • By occupation, flu vaccination coverage was highest among physicians (98.0%), nurses (92.0%), pharmacists (90.6%), and nurse practitioners and physician assistants (88.8%)
  • Flu vaccination coverage was lowest among other clinical health care personnel (81.7%), assistants and aides (72.4%), and nonclinical health care personnel (76.7%).
• By work setting, flu vaccination coverage was highest among HCP working in hospitals (93.2%).
  • Flu vaccination coverage continues to be lower among HCP working in long-term care (LTC) settings (69.3%) compared with those working in hospitals and ambulatory settings and physician offices (78.8%).
  • Vaccination coverage was highest (94.4%) among health care personnel working in settings where vaccination was required. Among health care personnel whose employers did not have a requirement for vaccination coverage was higher among those who worked in locations where vaccination was offered at the worksite at no cost for 1 day only (74.9%) or >1 day (89.4%) or who worked in locations where their employer did not provide influenza vaccination on-site at no cost but actively promoted vaccination through other mechanisms (73.3%), compared with that among health care personnel working in locations where employers did not have any vaccination-related requirements or provisions (52.3%).

• Visit Influenza Vaccination Coverage Among Health Care Personnel — United States, 2018–19 Influenza Season for more information.
• Visit A Toolkit for Long-term Care Employers: Increasing Influenza Vaccination among Healthcare Personnel in Long-term Care Settings.

Influenza (Flu) Facts

• People with flu can spread it to others. Influenza viruses are spread mainly by droplets made when people with flu cough, sneeze or talk. These droplets can land in the mouths or noses of people who are up to about 6 feet away or possibly be inhaled into the lungs. Less often, a person might get flu by touching a surface or object that has flu virus on it and then touching their own mouth or nose.
• Most healthy adults may be able to infect others beginning 1 day before symptoms develop and up to 5 to 7 days after becoming sick. Children may pass the virus for longer. Symptoms start 1 to 4 days after the virus enters the body. That means that you may be able to pass on the flu to someone else before you know you are sick, as well as while you are sick. Some persons can be infected with the flu virus but have no symptoms. During this time, those persons may still spread the virus to others.
• Some people, such as people 65 years and older, children younger than 5 years, pregnant women, and people with certain chronic health conditions like asthma, diabetes, or heart and lung disease, are at high risk of serious complications from flu.
• Since health care workers may care for or live with people at high risk for influenza-related complications, it is especially important for them to get vaccinated annually.
• Annual vaccination is important because influenza is unpredictable, flu viruses are constantly changing and immunity from vaccination declines over time.
• CDC recommends an annual flu vaccine as the first and best way to protect against influenza. This recommendation is the same even during years when the vaccine composition (the viruses the vaccine protects against) remains unchanged from the previous season.

Flu Vaccine Facts

• The seasonal flu vaccine protects against the influenza viruses that research indicates will be most common during the upcoming season. Trivalent vaccines are made to protect against three flu viruses; an influenza A (H1N1) virus, an influenza A (H3N2) virus, and an influenza B virus. Quadrivalent vaccines protect against four viruses; the same viruses as the trivalent vaccine as well as an additional B virus.
• Flu vaccines CANNOT cause flu. Flu vaccines are made with either killed or weakened viruses.
• Flu vaccines are safe. Serious problems from a flu vaccine are very rare. The most common side effect that a person is likely to experience is soreness where the injection was given. This is generally mild and usually goes away after a day or two. Visit Influenza Vaccine Safety for more information.

How Do Flu Vaccines Work?

The seasonal flu vaccine protects against the influenza viruses that research data suggest will be most common during the upcoming season. Antibodies develop in the body about two weeks after vaccination. These antibodies provide protection against infection from flu viruses that are the same as or similar to those used to make the vaccine.

What Viruses Does the 2020-2021 Vaccine Provide Protection Against?

Vaccines that give protection against three viruses are called trivalent vaccines. Vaccines that give protection against four viruses are called quadrivalent vaccines.

All 2020-2021 egg-based influenza vaccines are made to protect against the following three viruses:

• an influenza A/Guangdong-Maonan/SWL1536/2019 (H1N1)pdm09-like virus;
• an influenza A/Hong Kong/2671/2019 (H3N2)-like virus; and
• an influenza B/Washington/02/2019 (Victoria lineage)- like virus.

All 2020-2021 cell-based influenza vaccines are made to protect against the following three viruses:

• an influenza A/Hawaii/70/2019 (H1N1)pdm09-like virus;
• an influenza A/Hong Kong/45/2019 (H3N2)-like virus; and
• an influenza B/Washington/02/2019 (Victoria lineage)- like virus.

Most of the 2020-2021 flu vaccine is quadrivalent vaccine and also protects against an additional B virus (B/Phuket/3073/2013-like virus). This is a B/Yamagata lineage virus. The 2020–21 composition reflects updates in the influenza A(H1N1)pdm09, influenza A(H3N2), and influenza B (Victoria lineage) components.

More information about influenza vaccines is available at Preventing Seasonal Flu With Vaccination.

If I Got Vaccinated During a Past Season, Do I Need to Get Vaccinated This Season?

Yes. CDC recommends a yearly flu vaccine for everyone 6 months and older. This is for two reasons: vaccine compositions may be updated from one season to the next and a person’s immune protection from vaccination declines over time. So an annual vaccination is needed to get the “optimal” or best protection against flu.

When Should I Get Vaccinated?

Optimally, vaccination should occur before onset of influenza activity in the community. Health care providers should offer vaccination by the end of October. Getting vaccinated later, however, can still be beneficial and vaccination should continue to be offered throughout the flu season, even into January or later. Vaccination should continue to be offered as long as influenza viruses are circulating. While seasonal influenza outbreaks can happen as early as October, most of the time influenza activity peaks between December and February. Since it takes about two weeks after vaccination for antibodies to develop in the body that protect against influenza virus infection, it is best that people get vaccinated so they are protected before influenza begins spreading in their community.

Protect yourself, your family, and your patients by getting a flu vaccine this season.

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What Is CDC’s Position on Mandating Flu Vaccination for Health Care Workers?

The findings of a CDC review of related published literature indicate that influenza vaccination of health care personnel can enhance patient safety. ^1,2

CDC conducts science-based investigations, research, and public health surveillance both nationally and internationally. CDC adopts recommendations that are made by the Advisory Committee for Immunization Practices. These recommendations may be considered by state and other Federal agencies when making or enforcing laws. CDC also has infection control recommendations for health care settings. However, CDC does not issue any requirements or mandates for state agencies, health systems, or health care workers regarding infection control practices, including influenza vaccination or the use of masks.

Some employers require certain immunizations. Hospitals, for example, may require some staff to get a flu vaccine or hepatitis B vaccine or take other precautions such as the use of masks.

To find out more about the laws in your state and  to contact your state health department through Public Health Resources: State Health Departments.

State Immunization Laws for Healthcare Workers and Patients and Vaccines and Immunizations: Basics and Common Questions National Center for Immunization and Respiratory Diseases have more information. For more information, updates, and access to free materials to assist with educating staff and patients about the impact of influenza and the benefits of vaccination, visit CDC Seasonal Influenza (Flu) or call the National Immunization Hotline at (800) 232-2522 (English), (800) 232-0233 (español), or (800) 243-7889 (TTY).

More Information

Influenza Vaccination Coverage Among Health Care Personnel — United States, 2018–19 Influenza Season

Influenza Vaccination Coverage Among Health Care Personnel — United States, 2017–18 Influenza Season. MMWR Morb Mortal Wkly Rep 2018;67(38):1050-1054

Prevention and Control of Seasonal Influenza with Vaccines: Recommendations of the Advisory Committee on Immunization Practices — United States, 2019–20 Influenza Season

¹ Ahmed F, Lindley M, Allred N, Weinbaum C, Grohskopf L. Effect of Influenza Vaccination of Health Care Personnel on Morbidity and Mortality Among Patients: Systematic Review and Grading of Evidence. Clin Infect Dis 2013; epublished ahead of print.

² Griffin MR. Influenza Vaccination of Health Care Workers: Making the Grade for Action. Clin Infect Diseases 2013; epublished ahead of print.

Thomas RE, Jefferson T, Lasserson TJ. Influenza vaccination for healthcare workers who care for people aged 60 or older living in long-term care institutionsExternalexternal iconexternal icon. Cochrane Database of Systematic Reviews 2013, Issue 7. Art. No.: CD005187. DOI: 10.1002/14651858.CD005187.pub4.

Vanhems P, Voirin N, Roche S, Escuret V, Regis C et al. Risk of influenza-like illness in an acute health care setting during community influenza epidemics in 2004-2005, 2005-2006, and 2006-2007: a prospective studyExternalexternal iconexternal icon. Arch Intern Med 2011; 171(2);151-17.

Apisarnthanarak A, Uyeki T, Puthavathana P, Kitphati R, Mundy L. Reduction of seasonal influenza transmission among healthcare workers in an intensive care unit: A 4-year intervention study in Thailand. Infect Control Hosp Epidemiol 2010; 31(10);996-1003.

Turnberg W, Daniell W, Duchin J. Influenza vaccination and sick leave practices and perceptions reported by health care workers in ambulatory care settings. Am J Infect Control 2010; 38(6):486-8.

Salgado CD, Giannetta ET, Hayden FG, Farr BM. Preventing nosocomial influenza by improving the vaccine acceptance rate of clinicians. Infect Control Hosp Epidemiol 2004;25:923–8.

Saito R, Suzuki H, Oshitani H, Sakai T, Seki N, Tanabe N. The effectiveness of influenza vaccine against influenza A (H3N2) virus infections in nursing homes in Niigata, Japan, during the 1998–1999 and 1999–2000 seasons. Infect Control Hosp Epidemiol 2002;23:82–6.

Cunney RJ, Bialachowski A, Thornley D, Smaill FM, Pennie RA. An outbreak of influenza A in a neonatal intensive care unit. Infect Control Hosp Epidemiol 2000;21:449–54.

Saxen H, Virtanen M. Randomized, placebo-controlled double blind study on the efficacy of influenza immunization on absenteeism of health care workers. Pediatr Infect Dis J 1999;18:779–83.

Wilde JA, McMillan JA, Serwint J, Butta J, O’Riordan MA, Steinhoff MC. Effectiveness of influenza vaccine in health care professionals: a randomized trial. JAMA 1999;281:908–13.