The purpose of Men’s Health Week is to increase awareness of preventable health problems and encourage early detection and treatment of disease among men and boys.

According to the Mayo Clinic, the biggest threats to men’s health can often be prevented [1]. Here’s a list of the top seven threats to men’s health and what you can do to minimize those risks.

1. Heart disease

   Heart disease is the leading cause of death in U.S. males [2]. The good news is that measures can be taken to prevent heart disease. Here’s some things you can do to take charge of your heart health:

   • Don’t smoke. If you do smoke, quit smoking.
   • Eat a healthy diet of fruits, vegetables, whole grains, high-fiber foods, and lean sources of protein.
   • Manage chronic conditions such as high cholesterol or high blood pressure.
   • Include physical activity in your daily routine.
   • Watch your weight.
   • Limit alcohol consumption.
   • Take steps to reduce your stress.
2. Cancer

   The three most common cancers among men are prostate cancer, lung cancer and colorectal cancer [3]. Scientists estimate that about a third of the most common cancers could be prevented through diet and lifestyle [4]. Choose healthy lifestyle alternatives to reduce your risks for developing cancer:

   • Take a daily baby aspirin (75mg).
   • Don’t smoke. Avoid exposure to secondhand smoke.
   • Watch your weight.
   • Include physical activity in your daily routine.
   • Eat a healthy diet of fruits, vegetables, whole grains, high-fiber foods, and lean sources of protein.
   • Use sunscreen and protect yourself from the sun.
   • Limit alcohol consumption.
   • Take early detection seriously. Get regular cancer screenings.
3. Accidents

   Motor vehicle crashes are a leading cause of fatal accidents among men. When driving, use common sense: always wear your seat belt, don’t drive under the influence of drugs or alcohol, and don’t drive when you’re tired. Avoid distractions such as the radio or texting and follow the speed limit (this will also improve your financial health, reduce stress, and help save the planet).

4. Chronic lower respiratory diseases

   Chronic lung conditions such as bronchitis and emphysema are a concern for men. Here’s how you can protect your respiratory health:

   • Don’t smoke.
   • Pay attention to air quality; steer clear of pollutants.
   • Prevent respiratory infections. Wash your hands and get the yearly flu vaccine.
5. Stroke

   Stroke is the most common cause of adult disability. Although you can’t control some stroke risk factors, such as family history, age and race, you can control other contributing factors:

   • Manage chronic conditions such as high cholesterol or high blood pressure.
   • Don’t smoke.
   • Eat a healthy diet.
   • Include physical activity in your daily routine.
   • Limit alcohol consumption.
6. Type 2 diabetes

   Type 2 diabetes is the most common form of diabetes. It is a lifelong disease in which there are high levels of sugar (glucose) in the blood. To prevent type 2 diabetes, eat a healthy diet, exercise, and watch your weight. Research has shown that you can also lower diabetes risk by getting a good nights sleep.If you have diabetes, keep your blood sugar under control. Poorly controlled diabetes can lead to heart disease, eye problems, nerve damage and other complications.

7. Suicide

   Suicide is another leading men’s health risk. An important risk factor for suicide among men is depression. Depression is serious: changes in heart function are seen during major depression. Effective treatments for depression are available. If you have signs and symptoms of depression, such as feelings of sadness or unhappiness and loss of interest in normal activities, talk to your doctor.

The bottom line to men is to take these seven health threats seriously. The actions listed on this page will positively affect your health and increase the likelihood of living a long and healthy life.

References

1. Men’s health: Preventing the top 7 threats. Mayo Clinic. Accessed 2012 Jun 13.
2. Leading Causes of Death in Males United States. Centers for Disease Control and Prevention. Accessed 2012 Jun 13.
3. Cancer Among Men. Centers for Disease Control and Prevention. Accessed 2012 Jun 13.
4. Cancer prevention. World Cancer Research Fund. Accessed 2012 Jun 13.

Answer: First and foremost, it’s not possible to get the flu from a flu shot. There are two common forms of influenza vaccination. The first is an injection of inactivated virus, which is essentially virus that has been killed, and sometimes dismantled into pieces. Even though the virus has been inactivated, the immune system can still respond to it and “learns” the shape of the flu virus from the pieces present in the inoculation. This allows the immune system to respond rapidly upon subsequent exposure to the flu such that the virus will be eliminated before it can cause illness. Inactivated virus is incapable of causing illness, much the way the remains of a chicken dinner are incapable of laying an egg.

The second type of influenza vaccination is live, attenuated (meaning weakened) virus in the form of a nasal spray called FluMist. Despite the fact that the nasal spray contains live virus, the virus isn’t able to proliferate in the body and cause illness, because it’s been genetically modified to survive only at temperatures lower than core body temperature. As such, the virus can survive in the nose (such that the immune system can learn to recognize it and prevent future infection), but it can’t survive in the lungs or elsewhere in the body. The latter would be necessary for infection to occur.

There are a few possible reasons that an individual who’d been vaccinated for influenza could come down with “the flu.” The first, and most likely, is simply that the body reacts to the flu vaccine by generating an immune response to build immunity against a real attack. Because of this, people vaccinated against the flu feel kind of icky, tired, and may even come down with a headache or low grade fever. These symptoms are indicative of the body’s activated immune response to the flu vaccine, which is necessary to develop immunity against the live influenza virus.

Alternatively, what’s called “the flu” in common parlance is often a virus other than true influenza. The influenza vaccination can’t protect against colds or any of the many other respiratory viruses that are common during the winter months. As such, getting an upper respiratory infection after having been vaccinated for influenza isn’t an indication that the shot has failed to work. Influenza symptoms are characterized by fever (in most cases), muscle aches, headache and fatigue. It comes on much more rapidly — and is more severe in its presentation — than the common cold and many other seasonal respiratory viruses.

In the rare event that an individual is exposed to influenza shortly after vaccination, it is possible to come down with the flu. It takes the influenza vaccination approximately two weeks to take effect. During this time, the immune system is working on learning to recognize and respond to the virus, and an exposure soon after vaccination could result in illness. To preclude this, physicians generally recommend getting a flu shot well before the anticipated start of flu season.

Finally, there’s the outside chance that the flu shot could be ineffective against the flu in a particular year. Because the most common strains of influenza virus differ from year to year, health organizations must make educated predictions about which strains will likely be most prevalent. This creates a bit of a dilemma; the earlier predictions are made, the sooner the flu vaccine will be available, but the greater the chance the predictions won’t be completely accurate. Waiting until flu season starts to produce the vaccine would nearly guarantee the vaccine’s effectiveness, but would be unwise, because susceptible populations would be left unprotected for the beginning of the flu season.

In general, the flu shot is quite effective and the vast majority of vaccinated individuals do not get influenza. The flu can be quite serious — particularly in patients with respiratory disease, the elderly, and the immunocompromised. Approximately 200,000 hospitalizations and thousands to tens of thousands of deaths occur every year because of the flu [1]. Since it’s not possible to get the flu from a flu vaccine, and the virus hospitalizes and kills more people in this country than any other vaccine-preventable disease, the benefits of the flu vaccine clearly outweigh its riskss, even if it doesn’t 100% preclude the possibility of the flu.

Besides getting the flu shot, one of the best ways to avoid getting sick is to wash hands frequently. Remember that simply coughing or sneezing can spread cold and flu germs.

Q&A is a biweekly series answering YOUR questions about the science of health. Have a question? Use the contact form to ask us!

References

1. Key Facts About Seasonal Influenza (Flu). Centers for Disease Control and Prevention. Updated 2007, Sep 17.

Each year, experts from the FDA, World Health Organization, CDC, and others in the public health community study virus samples and patterns collected worldwide to identify virus strains likely to cause the most illness during the upcoming influenza season. Currently, there are 136 national influenza centers in 106 countries that conduct year-round surveillance for influenza viruses and disease activity. Based on the information that’s been collected and the recommendations of the FDA’s Vaccines and Related Biological Products Advisory Committee, the strains selected for the Northern Hemisphere’s 2011-2012 influenza season are:

• A/California/7/2009 (H1N1)-like virus (pandemic (H1N1) 2009 influenza virus)
• A/Perth /16/2009 (H3N2)-like virus
• B/Brisbane/60/2008-like virus

Six manufacturers are licensed to produce and distribute flu vaccines in the U.S. this year (brand names in parenthesis): CSL Limited (Afluria); GlaxoSmithKline Biologicals (Fluarix); ID Biomedical Corporation (FluLaval); MedImmune Vaccines Inc. (FluMist); Novartis Vaccines and Diagnostics Limited (Fluvirin); and Sanofi Pasteur Inc. (Fluzone, Fluzone High-Dose and Fluzone Intradermal).

For 2011, a new vaccine is also available. Sanofi’s Fluzone Intradermal was approved by the FDA in May [2]. It’s a shot that, unlike traditional flu shots, is injected under the skin instead of into the muscle. The company says the needle is 90% shorter than the kind used for intramuscular injection.

Cold and flu germs hide everywhere and everyone is at risk. Early last year, the CDC’s Advisory Committee on Influenza Practices recommended that everyone 6 months of age and older receive an annual influenza vaccination [3].

Flu season runs from November to April — most cases occur between late December and early March. Every winter, approximately 10-20% of people get the flu [4]. In children, the odds are even worse, with up to 40% of children becoming clinically ill due to the influenza virus. The most effective method to prevent infection, reduce symptom severity if you do get sick, and prevent the spread of virus to others is annual vaccination. Besides vaccination, one of the easiest ways to avoid getting sick is to wash your hands.

References

1. FDA approves vaccines for the 2011-2012 influenza season. U.S. Food and Drug Administration News Release. 2011 Jul 18.
2. FDA Licenses Sanofi Pasteur’s New Influenza Vaccine Delivered by Intradermal Microinjection. Sanofi Pasteur. 201 May 10.
3. CDC’s Advisory Committee on Immunization Practices (ACIP) Recommends Universal Annual Influenza Vaccination. Centers for Disease Control and Prevention press release. 2010 Feb 24.
4. Evans M. Flu shot. Can Fam Physician. 2005 Nov;51:1511-2, 1515-6.
   View abstract

What is influenza?

Influenza is a respiratory infection caused by a number of airborne RNA viruses that enter the body through the nose or mouth. Influenza viruses bind to epithelial cells in the nose, throat and lungs. Cells than absorb the virus. Once inside, the virus replicates using a cellular enzyme called an RNA-dependent RNA polymerase. The polymerase enzyme lacks proofreading capability and makes a spontaneous mutation at a rate of 1 per genome per replication [2]. Thus, essentially every influenza virus replicated contains a mutation. This is the reason why influenza viruses continually change over time and are able to evade the host immune system.

Symptoms of the flu present quickly and are worse than the common cold. Flu symptoms include body or muscle aches, chills, cough, high fever lasting 3-4 days, headache, sore throat, stuffy nose, extreme tiredness and stomach symptoms (more common in children), including nausea, vomiting and diarrhea. The incubation period between acquiring the infection and becoming ill is 1-4 days. Most heathy adults are able to infect other people 1 day before symptoms develop and up to 5 days after becoming sick [3]. Viral shedding, the period during which a person can infect others, usually peaks on the second day of symptoms. Children can infect others for several days prior to developing symptoms and can be infectious for more than 10 days. Since children can shed the greatest amounts of virus, they pose the greatest risk for viral transmission.

The flu vaccine: your options

The best way to prevent seasonal flu is to get vaccinated. Hospitalization and death from flu complications pose real risks; every year, on average, more than 200,000 people are hospitalized from flu complications and approximately 36,000 people die from the flu [3]. Immunizing children against influenza is perhaps the best method to reduce the occurrence of the flu in the community. If children receive the flu shot but the rest of the family abstains, the influenza attack rate drops by 40%; if parents also get the flu shot, the influenza attack rate drops by 80% [4].

The flu vaccine is available in two forms, a shot and a nasal spray (FluMist). The flu shot, which is approved for use in children 6 months and older, contains an inactivated flu virus. Although you may develop a slight reaction to the shot, including soreness at the injection site, muscle ache or fever, you won’t get the flu because the viruses in the vaccine have been inactivated. The nasal spray flu vaccine (FluMist), which is approved for use in children 2 years and older, contains a low dose of live but weakened flu virus. Similar to the flu shot, the nasal spray doesn’t cause the flu, but prompts an immune response so that your body develops antibodies necessary to fight influenza infection. A review of 48 reports on influenza vaccine efficacy over the past four decades found that the flu shot was 80% efficacious against influenza in healthy adults when the vaccine matched the circulating strain and the circulation was high [5]. If the circulating strain didn’t match the vaccine, efficacy was reduced to 50%. The flu vaccine was 30% effective against influenza-like illness. FluMist efficacy has been reported to be higher in both children and adults [6-8].

What else can you do?

In addition to the flu vaccine, one of the best ways to avoid getting sick and stay healthy is to simply wash your hands. Even something as simple as coughing or sneezing can spread cold and flu germs; hand washing is the single most important thing you can do to prevent the spread of infection and to stay healthy. Some scientists estimate that as much as 80% of all infections are transmitted by unwashed hands [9]. Nevertheless, a dab of soap and a quick rinse isn’t effective. The key is to wash your hands for at least 20 seconds to ensure that you’ve removed the microbes (here’s a trick: sing the ABC’s to yourself). By rubbing your hands with soapy water, you pull dirt and oil from your skin. The soap lather suspends any germs trapped inside and are then washed away when rinsing. If soap and water aren’t available, use an alcohol-based hand sanitizer. However, while alcohol-based hand sanitizers reduce the number of germs on skin, they aren’t necessarily more effective at reducing the flu virus on human hands. Studies have found that hand washing with soap and water is superior to all alcohol-based treatments.

References

1. Evans M. Flu shot. Can Fam Physician. 2005 Nov;51:1511-2, 1515-6.
   View abstract
2. Drake JW. Rates of spontaneous mutation among RNA viruses. Proc Natl Acad Sci U S A. 1993 May 1;90(9):4171-5.
   View abstract
3. Key Facts About Seasonal Influenza (Flu). Centers for Disease Control and Prevention. Updated 2007, Sep 17.
4. Hurwitz et al. Effectiveness of influenza vaccination of day care children in reducing influenza-related morbidity among household contacts. JAMA. 2000 Oct 4;284(13):1677-82.
   View abstract
5. Jefferson et al. Vaccines for preventing influenza in healthy adults. Cochrane Database Syst Rev. 2007 Apr 18;(2):CD001269.
   View abstract
6. Belshe et al. The efficacy of live attenuated, cold-adapted, trivalent, intranasal influenzavirus vaccine in children. N Engl J Med. 1998 May 14;338(20):1405-12.
   View abstract
7. Belshe et al. Efficacy of vaccination with live attenuated, cold-adapted, trivalent, intranasal influenza virus vaccine against a variant (A/Sydney) not contained in the vaccine. J Pediatr. 2000 Feb;136(2):168-75.
   View abstract
8. Treanor et al. Evaluation of trivalent, live, cold-adapted (CAIV-T) and inactivated (TIV) influenza vaccines in prevention of virus infection and illness following challenge of adults with wild-type influenza A (H1N1), A (H3N2), and B viruses. Vaccine. 1999 Dec 10;18(9-10):899-906.
   View abstract
9. Put Your Hands Together. National Center for Preparedness, Detection, and Control of Infectious Diseases (NCPDCID) and National Center for Zoonotic, Vector-Borne, and Enteric Diseases (NCZVED). 2008 Oct 13.

Both vaccines were generated from the same vaccine virus (New York Medical College [NYMC] X-179A), and formulated and produced by either CSL Biotherapies [1] or Novartis [2]. The Novartis vaccine is being tested both with and without the company’s proprietary immune-stimulating compound (called an adjuvant), MF59. The NEJM report described below is an interim analysis of subject responses to adjuvanted vaccine. The CSL vaccine does not contain an adjuvant. Adjuvanted flu vaccines have not been used previously in the U.S. and health officials hope to use a vaccine without an adjuvant because of the regulatory issues involved (more extensive human testing would be required before FDA approval). MF59 has been used extensively in Europe since 1997 with no excess reports of autoimmune conditions.

The CSL Biotherapies H1N1 vaccine

The CSL Biotherapies vaccine was tested in one locality in Australia during winter at two different doses on 240 people (120 for each dose). An equal number of subjects from 18–49 years of age (59% female, 86% white, 43% had previously received seasonal influenza vaccine) and 50–64 years of age (53% female, 98% white, 48% had previously received seasonal influenza vaccine) were evaluated using a 15 microgram dose.

The study also evaluated a double dose (30 micrograms) that many people assumed would be necessary in another group of 120 subjects.

Although a robust immune response to the H1N1 vaccine following a single dose was unanticipated, post vaccination titers of 1:40 or more on hemagglutination-inhibition assay (a quantification of virus by hemagglutination) was observed in 96.7% of the recipients that received the 15 microgram dose and 93.3% of the recipients that received the 30 microgram dose. Titers of 1:40 or greater are considered to be protective. Thus, the low dose actually worked better than the double dose.

Surprisingly, 31.7% of subjects had antibody titers before vaccination of 1:40 or more on hemagglutination-inhibition assay. For subjects who were 50 years of age or older, the researchers suggest that this could be due to the presence of preexisting antibodies from exposure to H1N1 viruses circulating prior to 1957. For younger subjects, there may be a degree of previous 2009 H1N1 infection despite stringent exclusion criteria. Additionally, cross-reactive antibodies may also have played a role.

An increase in detectable specific H1N1 antibodies in blood serum (called seroconversion) occurred in 74.2% of subjects.

No deaths or serious adverse events were reported. The most commonly reported local adverse events within 7 days after receiving one dose of the H1N1 vaccine were injection-site tenderness and pain. Systemic adverse events reported were headache, malaise and muscle pain.

The Novartis H1N1 vaccine

The Novartis vaccine was tested in one locality in the U.K. during summer on 100 people aged 18–50 (65% female, 82% white, 37% had previously received seasonal influenza vaccine). The vaccine is boosted with the Novartis adjuvant, MF59.

Subjects were randomly assigned in 5 blocks of 20 patients to receive two doses of 7.5 micrograms of MF59-adjuvanted vaccine either concurrently administered on day 0 or administered in two doses, the first at day 0 and the second at day 7, 14 or 21. Data were evaluated at day 21 for four groups of 25 subjects:

• one dose on day 0
• two doses on day 0
• one dose on day 0 and one dose on day 7
• one dose on day 0 and one dose on day 14

Similar to what was observed in the CSL vaccine study, 15% of subjects had detectable prevaccination levels of hemagglutination-inhibition antibody. The researchers suggest that, despite excluding subjects with previous respiratory illness, this may be due to asymptomatic H1N1 infection.

By day 21, post-vaccination titers exceeded 1:32 by hemagglutination-inhibition assay in 88% of subjects who had received one vaccine dose by this time and in 92–100% of subjects who had received both doses.

The development of detectable specific H1N1 antibodies in blood serum occurred in 76% of subjects that received only one dose to date and 88–92% that received both doses.

No deaths or serious adverse events were reported. The most commonly reported local adverse event within 7 days after receiving the first dose of the H1N1 vaccine was injection-site pain. Systemic adverse events reported were headache, muscle pain, malaise and nausea.

More data to come

The discrepancies observed between the two trials may be due to several factors: technical differences in measurement of antigen in the doses used, the limited number of samples evaluated and the early time point following immunization. Additional companies — Sanofi Pasteur, GlaxoSmithKline and AstraZeneca — should be announcing preliminary trial results shortly. H1N1 vaccine studies in children started after the adult studies and aren’t completed yet. Researchers anticipate those results in two weeks.

For more information on seasonal influenza (flu) and H1N1 swine flu, visit the following websites:

• CDC seasonal flu pages
• Flu.gov

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References

1. Greenberg et al. Response after One Dose of a Monovalent Influenza A (H1N1) 2009 Vaccine — Preliminary Report. N Engl J Med. 2009 Sep 10. [Epub ahead of print] DOI: 10.1056/NEJMoa0907413
   View abstract
2. Clark et al. Trial of Influenza A (H1N1) 2009 Monovalent MF59-Adjuvanted Vaccine — Preliminary Report. N Engl J Med. 2009 Sep 10. [Epub ahead of print] DOI: 10.1056/NEJMoa0907650
   View abstract
3. Exclusive: Sebelius Says H1N1 Vaccine To Be Released Earlier Than Expected. ABC News, George’s Bottom Line. 2009 Sep 13.

The best way to prevent seasonal flu is to get a flu vaccination. Hospitalization and death from flu complications pose real risks. Every year, on average, more than 200,000 people are hospitalized from flu complications and approximately 36,000 people die from the flu [2].

Additionally, immunizing children against influenza is perhaps the best method to reduce the occurrence of the flu in the community. If children receive the flu shot but the rest of the family abstains, the influenza attack rate drops by 40%; if parents also get the flu shot, the influenza attack rate drops by 80% [3].

What is influenza?

Influenza is a respiratory infection caused by a number of RNA viruses. An airborne virus, the flu enters your body through your nose or mouth. Influenza viruses bind to sialic acid sugars (essentially a carbohydrate widely distributed in animal tissues and bacteria) found on the surface of epithelial cells in the nose, throat and lungs via a protein called hemagglutinin. The cell then absorbs the virus in a process called endocytosis. Once inside the cell, the virus replicates. An enzyme called a RNA-dependent RNA polymerase is responsible for replicating the viral RNA. The polymerase enzyme lacks proofreading capability and makes a spontaneous mutation at a rate of 1 per genome per replication [4]. Thus, essentially every influenza virus replicated is a mutant. This is the reason why influenza viruses continually change over time and are able to evade the host immune system.

As an interesting side note, increased sialic acid levels have been observed during inflammatory processes and in cancer (correlating with the degree of metastasis), alcohol abuse, diabetes and chronic renal failure [5].

Symptoms of the flu present quickly and are worse than the common cold. Flu symptoms include:

• Body or muscle aches
• Chills
• Cough
• High fever, lasting 3-4 days
• Headache
• Sore throat
• Stuffy nose
• Extreme tiredness
• Stomach symptoms (more common in children), including nausea, vomiting and diarrhea.

The incubation period between acquiring the infection and becoming ill is 1 — 4 days. Most heathy adults are able to infect other people 1 day before symptoms develop and up to 5 days after becoming sick [2]. Viral shedding, the period during which a person can infect others, usually peaks on the second day of symptoms. Children can infect others for several days prior to developing symptoms and can be infectious for more than 10 days. Since children can shed the greatest amounts of virus, they pose the greatest risk for viral transmission.

Who should get vaccinated?

The Centers for Disease Control and Prevention (CDC) recommends that people at high risk for complications from the flu should get a flu vaccination [2], including:

• Children 6 months to 5 years of age
• Pregnant women
• People 50 years of age and older
• People of any age with certain chronic medical conditions
• People who live in nursing homes and other long term care facilities

Additionally, people who live or care for those at high risk for complications from flu (listed above) should also get vaccinated. For families with young children, this means everyone in the household needs to be vaccinated.

Indeed, recent studies suggest that pediatric influenza is a greater medical problem that was previously thought, since it can cause excess hospitalizations, medical visits and antibiotic prescriptions [6-8].

People who have a severe allergy to chicken eggs or who have had a severe reaction to an influenza vaccination previously should not be vaccinated without first consulting with their physician. Those individuals that are sick with fever should refrain from vaccination until their symptoms lessen.

Vaccination options and efficacy

The flu vaccine is available in two forms, a shot and a nasal spray (FluMist). The flu shot, which is approved for use in children 6 months and older, contains an inactivated flu virus. Although you may develop a slight reaction to the shot, including soreness at the injection site, muscle ache or fever, you won’t get the flu because the viruses in the vaccine have been inactivated (killed).

The nasal spray flu vaccine (FluMist), which was recently approved for use in children 2 years and older [9], contains a low dose of live but weakened flu virus. Similar to the flu shot, the nasal spray doesn’t cause the flu, but prompts an immune response so that your body develops antibodies necessary to fight influenza infection.

A review of influenza vaccine efficacy was recently published, examining the results of 48 reports over the past four decades [10]. The study found that the flu vaccine (specifically, inactivated parenteral vaccines, i.e. the flu shot) was 80% efficacious against influenza in healthy adults (in those confirmed by laboratory tests) when the vaccine matched the circulating strain and the circulation was high. If the circulating strain didn’t match the vaccine, efficacy was reduced to 50%. The flu vaccine was 30% effective against influenza-like illness. FluMist efficacy has been reported to be higher in both children and adults [11-13].

In addition to vaccination, one of the best ways to avoid getting sick is to simply wash your hands. Remember that even something as simple as coughing or sneezing can spread cold and flu germs.

You can protect yourself and those around you from the flu. Annual vaccination is the most effective method to prevent infection, reduce symptom severity (if you do get sick) and prevent the spread of virus to others.

References

1. Evans M. Flu shot. Can Fam Physician. 2005 Nov;51:1511-2, 1515-6.
   View abstract
2. Key Facts About Seasonal Influenza (Flu). Centers for Disease Control and Prevention. Updated 2007, Sep 17.
3. Hurwitz et al. Effectiveness of influenza vaccination of day care children in reducing influenza-related morbidity among household contacts. JAMA. 2000 Oct 4;284(13):1677-82.
   View abstract
4. Drake JW. Rates of spontaneous mutation among RNA viruses. Proc Natl Acad Sci U S A. 1993 May 1;90(9):4171-5.
   View abstract
5. Sillanaukee et al. Occurrence of sialic acids in healthy humans and different disorders. Eur J Clin Invest. 1999 May;29(5):413-25.
   View abstract
6. Neuzil et al. Burden of interpandemic influenza in children younger than 5 years: a 25-year prospective study. J Infect Dis 2002;185:147-52.
   View abstract
7. Izurieta et al. Influenza and the rates of hospitalization for respiratory disease among infants and young children. N Engl J Med. 2000 Jan 27;342(4):232-9.
   View abstract
8. Neuzil et al. The effect of influenza on hospitalizations, outpatient visits, and courses of antibiotics in children. N Engl J Med 2000;342:225-31.
   View abstract
9. FDA Approves Nasal Influenza Vaccine for Use in Younger Children. U.S. Food and Drug Administration. 2007 Sep 19.
10. Jefferson et al. Vaccines for preventing influenza in healthy adults. Cochrane Database Syst Rev. 2007 Apr 18;(2):CD001269.
    View abstract
11. Belshe et al. The efficacy of live attenuated, cold-adapted, trivalent, intranasal influenzavirus vaccine in children. N Engl J Med. 1998 May 14;338(20):1405-12.
    View abstract
12. Belshe et al. Efficacy of vaccination with live attenuated, cold-adapted, trivalent, intranasal influenza virus vaccine against a variant (A/Sydney) not contained in the vaccine. J Pediatr. 2000 Feb;136(2):168-75.
    View abstract
13. Treanor et al. Evaluation of trivalent, live, cold-adapted (CAIV-T) and inactivated (TIV) influenza vaccines in prevention of virus infection and illness following challenge of adults with wild-type influenza A (H1N1), A (H3N2), and B viruses. Vaccine. 1999 Dec 10;18(9-10):899-906.
    View abstract