During the 2006–2007 season, influenza circulated at epidemic levels for about 14 weeks and peaked during February, the month most frequently associated with peak activity over the past 31 influenza seasons.
Influenza epidemics occur every year in the United States, typically beginning in the late
fall or winter and concluding during the spring.1 During the 2006—2007 season, influenza
circulated at epidemic levels for about 14 weeks and peaked during February, the month
most frequently associated with peak activity over the past 31 influenza seasons.1,2 According
to estimates from the Centers for Disease Control and Prevention (CDC), influenza has
caused roughly 36,000 deaths and 226,000 hospitalizations annually.3,4 However, the rate
of flu varies each year based on viral virulence and duration of circulation. Complications,
hospitalizations, and death are most common in patients aged =65 years.5,6 In recent years,
there has been a growing recognition among oncologists and other cancer care professionals
of the importance of vaccination against influenza in patients with cancer.
For most people with cancer, vaccination for influenza is not only safe, but also a crucial part
of staying as healthy as possible. Owing to their weakened immune system, patients with cancer
are at high risk for infection with flu and pneumonia viruses, which can be lethal in these individuals.
Yearly flu and pneumonia shots often prevent infection entirely and can lessen the severity
of illness in those who do get sick.
Influenza viruses are divided into three types, designated A, B, and C. Influenza types A and
B are responsible for epidemics of respiratory illness that occur almost every winter and are
often associated with increased rates for hospitalization
and death. Influenza type C differs from types A and B in some important ways.
Type C infection usually causes either a very mild respiratory illness or no symptoms at all;
it does not cause epidemics and does not have the severe public health impact that influenza
types A and B do. Efforts to control the impact of influenza are aimed at types A and B.
Influenza type A viruses are divided into subtypes based on differences in two viral proteins
called the hemagglutinin (H) and the neuraminidase (N). The current subtypes of influenza A
are designated A(H1N1) and A(H3N2). Influenza A(H1N1), A(H3N2), and influenza B strains are
included in each year’s influenza vaccine. In the years since its emergence, type A(H3N2) epidemics
have caused more than 400,000 deaths in the United States alone, and more than 90% of
these deaths have occur-red among people age 65 and older.
Influenza type A viruses undergo two kinds of changes. One is a series of mutations that
occur over time and cause a gradual change in the virus. This is called antigenic “drift.” This
constant changing enables the virus to evade the immune system of its host, so that people
are susceptible to influenza virus infection throughout life. This process works as follows:
A person infected with influenza virus develops antibody against that virus; as the virus
changes, the “older” antibody no longer recognizes the “newer” virus, and reinfection can occur.
The older antibody can, however, provide partial protection against re-infection.
The other kind of change is an abrupt change in the hemagglutinin and/or the neuraminidase
proteins. This is called antigenic “shift.” In this case, a new subtype of the virus suddenly
emerges. Type A viruses undergo both kinds of changes; influenza type B viruses change only
by the more gradual process of antigenic drift.
CDC Recommendations For Influenza Vaccination
Influenza vaccination is the most effective method for preventing influenza virus infection
and its complications, which may be severe The CDC updated its recommendations
regarding who should receive influenza vaccination in 2008.1,7 Current recommendations
regarding annual vaccination in children/adolescents and adults are summarized in Table 1
and Table 2, respectively. It is important to note that patients with cancer may fall into several
of the categories shown in the tables.
In 2008, the Advisory Committee on Immunization Practices (ACIP) of the CDC expandedits
recommendations for influenza vaccination for school-aged children.1,7 The ACIP-CDC
now recommends that all children aged six months to 18 years receive annual influenza
vaccination, beginning in 2008 if feasible, but beginning no later than during the 2009—2010
Since influenza viruses undergo frequent antigenic change, persons recommended for
vaccination must receive an annual vaccination against the viruses known to be in circulation
According to the CDC,1 trivalent influenza vaccine may be used for any person aged
=6 months, including those with high-risk conditions. The 2008—2009 trivalent vaccine
virus strains are A/Brisbane/59/2007 (H1N1)-like, A/Brisbane/10/2007 (H3N2)-like,
and B/Florida/4/2006-like antigens.1 Live, attenuated-virus vaccine is currently approved
only for healthy, nonpregnant persons aged 5—49 years.
Flu Vaccination in Patients With Cancer
According to the CDC, less than 30% of patients with high-risk conditions, including cancer,
were vaccinated against flu in 2005.8 Table 3 shows flu vaccination coverage levels in persons
with high-risk conditions, including cancer, by age. Data shown in the table were derived
from the National Health Interview Survey and National Immunization Survey, US, 2005.
The results of a survey presented on October 27, 2007 at the 49th annual meeting of the
American Society for Therapeutic Radiation and Oncology (ASTRO) in Los Angeles (Poster
2641) highlight the poor flu vaccination coverage in patients with cancer specifically.9 About
a third of patients who responded to an anonymous survey said they had not had a flu vaccination,
according to Neha Vapiwala, MD, University of Pennsylvania, Philadelphia, PA, and
one of the authors of the presented study. The survey was completed by 214 consecutive
cancer outpatients at the University of Pennsylvania from August 2006 to January
2007. Ninety-eight percent of the questionnaires were complete and usable for analysis.
This was the first performed to evaluate whether patients with cancer are compliant
with national vaccination guidelines. Patients who reported not receiving flu vaccine were
asked further questions about the reasons why they didn’t receive it.
Key findings from the study were as follows:
• Thirty percent of patients said they had never
had the flu vaccine, and another 9% said they
were not getting vaccinated yearly.
• About 60% of unvaccinated patients said they
didn’t know they needed a flu shot.
• Among patients aged 50 and older—i.e., those
recommended for a flu shot—33% had never
• Among patients who got their shots, 66% said
they heard about the vaccines from a health
care provider other than one providing cancer
care. Only ten% of patients were told about flu
vaccine by an oncologist.
Dr. Vapiwala reiterated, “Despite being seen by many clinicians for their cancer care, only one
in ten patients who actually got vaccinations said the shots had been recommended by their
When asked about potential reasons for the suboptimal flu vaccination in patients with cancer,
Dr. Vapiwala explained, “It’s a communications gap. Oncologists tend to assume that vaccinations
are being handled by the primary care provider, while the primary care physician may
assume the opposite. It’s not clear to patients and it’s not clear to physicians necessarily who
is responsible for what.”
Clearly, a key reason for not receiving flu vaccine was not knowing about the vaccine,
thinking it was not needed, or not having it recommended by a physician. The issue is important
because patients who have malignancies and who undergo cancer treatment are at
greater risk of acquiring viral illnesses such as influenza. They also tend to have a more severe
course and a more difficult recovery once they develop an infection.
Although the study was small and focuses on a single institution, Dr. Vapiwala said she
thinks the communication gap is a general problem. “Somebody has to take responsibility
[for routine care issues], and right now, it’s a gray area.” She added, “Oncologists have the
opportunity to talk to patients about recommended vaccines during their frequent interactions
with patients, whether it be before, during, or after cancer therapy. This discussion
could result in better cancer care and ultimately save lives.”
Newest Trivalent Influenza Vaccine
Afluria is a mercury-free, purified, inactivated, trivalent influenza vaccine propagated in embryonic
chicken eggs. Each dose contains the required dose of influenza virus hemagglutinin
antigens from the influenza strains recommended and prioritized by the FDA’s Vaccine and Related
Biological Products Advisory Committee
for each flu season. Afluria was approved by
the FDA in September 2007 for the active immunization
of persons =18 years of age against
influenza disease caused by influenza subtypes
A and type B present in the vaccine.
The CDC recommend an annual flu shot for patients with cancer 50 years and older and
yearly pneumonia shots for patients older than 65 years. In a 2007 survey of people undergoing
radiation treatment for cancer, scientists found that among those who meet CDC
guidelines for annual vaccination, 25% have never had a flu shot and more than 30% had
never been vaccinated against pneumonia. Since patients with cancer have weakened
immune systems, they are especially susceptible to flu and pneumonia. Family members and
close contacts of these individuals also have an increased risk of infection and the CDC
advises them to make annual vaccinations a health priority.
1. Centers for Disease Control and Prevention. Prevention
and control of influenza. Recommendations of the Advisory
Committee on Immunization Practices (ACIP), 2008.
2. Centers for Disease Control and Prevention. Update: Influenza
activity—United States and worldwide, 2006—2007
season, and composition of the 2007—2008 influenza
vaccine. MMWR 2007;56:789-794.
3. Thompson WW, Shay DK, Weintraub E, et al: Mortality associated
with influenza and respiratory synctyial virus in
the United States. JAMA 2003;289:179-186.
4. Thompson WW, Shay DK, Weintraub E, et al: Influenzaassociated
hospitalizations in the United States. JAMA
5. Barker WH, Mullooly JP: Impact of epidemic type A influenza
in a defined adult population. Am J Epidemiol
6. Neuzil KM, Wright PF, Mitchel EF, et al: The burden of influenza
illness in children with asthma and other chronic
medical conditions. J Pediatr 2000;137:856-864.
7. Centers for Disease Control and Prevention. Influenza
vaccine workgroup report. 2008. Available at: http://
jun08/32-3-flu.pdf. Accessed August 9, 2008.
8. Centers for Disease Control and Prevention. Prevention
and control of influenza. Recommendations of the Advisory
Committee on Immunization Practices (ACIP), 2007.
9. Yee S, Dutta P, Solin L, et al: Compliance with national vaccination
guidelines in patients receiving radiation therapy.
Int J Rad Onc Biol Physics 2007;69(suppl):S560.