It’s That Time of Year: Understanding the Influenza Virus

Daniel J Hyman, DO

Daniel J Hyman, DO

As we enter the heart of winter, it’s that time of year to start thinking about influenza (flu) prevention.  The Centers for Disease Control and Prevention (CDC) monitors the prevalence of flu and recently announced that influenza activity in the United States is currently increasing. New Jersey is also seeing an increase in flu activity in the past several weeks.

Influenza is a very contagious illness that tends to occur in outbreaks. The majority of illnesses caused by the flu are self-limited and often mild to moderate in severity. There are two main types of influenza viruses: A and B. Human influenza A and B viruses cause seasonal epidemics of disease almost every winter in the United States. The emergence of a new and very different influenza virus to infect people can cause influenza outbreaks and epidemics.

The typical flu symptoms include acute onset of muscle aches, fever as high as 103 degrees Fahrenheit, upper respiratory symptoms including sore throat, runny nose, cough, and extreme fatigue.

Gastrointestinal symptoms are less common in flu. Although often called the “stomach flu,” these type of illnesses that cause nausea, diarrhea, and vomiting are typically triggered by rotaviruses or bacteria and aren’t related to influenza. While these illnesses can occur anytime of the year, they are also highly contagious and common in the winter months as well while people are together in close quarters indoors. It is not unusual for these illnesses to spread quickly through families, school groups, or others in close proximity.

While everyone should be concerned with influenza, certain people are at high risk for complications of the flu. This includes the elderly, the very young, and people with chronic medical conditions including diabetes, COPD, and those who are immune compromised.

Prevention is the key to decreasing the incidents of outbreaks and epidemics. The CDC recommends flu vaccine for all individuals 6 months of age and older. The vaccination period for the flu begins in August and ends in April. There is a two-week lag time between receiving the vaccine and having adequate immunity against the flu. Several vaccines are available for influenza A and B. These vaccines contain antigens that were developed based on best medical knowledge from prior history of influenza outbreaks. An antigen is any substance that causes your immune system to produce antibodies against it.

Available vaccines are:

  • Trivalent vaccine – This is the most traditional flu vaccine that is made to protect against three different flu viruses.
  • Quadrivalent vaccine – Like the trivalent vaccine, but contains four influenza antigens.
  • Intradermal trivalent vaccine – Contains a low amount of antigen which is injected into the skin, instead of the muscle, with a much smaller needle. This is preservative-free and given to individuals 18 to 64 years of age.
  • High-dose vaccine – Contains four times the amount of antigen than the normal flu vaccine. It is indicated for patients ages 65 and above. Studies have shown a significantly higher antibody response in patients who receive this vaccine and preliminary data show a decrease rate of influenza.
  • Nasal vaccine – This vaccine is indicated for patients 2 years to 49 years of age. It is a live, attenuated vaccine so it should not be given to pregnant women, those who are immune compromised, or children with significant asthma.
  • Other – Cell-based, recombinant, adjuvant vaccines are also being use more frequently.

Another good way to help prevent the spread of flu and other seasonal illnesses is by practicing good hand hygiene. It is important to frequently wash your hands, especially if you have been in public places such as shopping malls, schools, sporting events, or using public transportation. Thoroughly wash your hands with warm water and soap, taking care to clean between your fingers. Waterless hand sanitizers are good to use when soap and water are not available. Many stores and public places now provide these for use.

Despite the best efforts, some patients do develop flu. Most cases are self-limited and are treated with nothing more than supportive care including fluids, rest, and over-the-counter medications. Four antiviral drugs are available to treat acute flu. They are Oseltamivir (Tamiflu), Zanamivir (Relenza), Peramivir (Rapivab), and Baloxavir Marboxil (Xofluza). These medications are used in high-risk individuals including patients with COPD and diabetes. Additionally, use of these medications is considered in both the very young and the very elderly. All individuals suspected of having the flu should stay home from work or school to decrease the risk of outbreaks. As with all viral illnesses, one of the best ways to prevent the spread is good old-fashioned hand washing.


Daniel J. Hyman, DO is the Head of the Division of General Internal Medicine at Cooper University Health Care. Concerned about symptoms? Visit an Urgent Care Center by clicking here, or learn more about our Primary Care services by clicking here.

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