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If It’s Fall, It Must Be Time For The Flu Shot

posted in Medication News

     With the arrival of autumn each year comes falling leaves, falling temperatures, the ‘Fall Classic’ (unfortunately without a Chicago team this year!)—and the rise in questions about the ‘flu shot.’  Questions about ‘the pneumonia shot’ also tend to come up at the same time.  Let’s go over the distinctions between the two shots, which are different vaccines that stimulate the immune system to protect us from separate infections.

What does each vaccine do?
     The ‘flu shot’ is the influenza vaccine.  It can only protect against the influenza virus. But, there are other types of viruses that can cause similar symptoms.
     The ‘pneumonia shot’ is the pneumococcal pneumonia vaccine, which only protects against just one bacteria that causes pneumonia—Streptococcus, i.e. ‘Strep,’ Pneumomiae.  But, Strep Pneumoniae is one of the most common causes of pneumonia that is acquired outside of a hospital.

Who is supposed to receive these vaccine?
     Influenza Vaccine:  Everyone over 6 months old is advised to receive the influenza vaccine because people typically develop symptoms to various degrees from exposure to the virus.
     Pneumococcal Pneumonia Vaccine:  Those who are under age 65 with certain chronic conditions and those over age 65–who are more likely than the general population to have chronic medical conditions—are advised to receive the pneumococcal pneumonia vaccine because chronic conditions can complicate recovery from this bacterial infection.  Children under the age of 2 are also supposed to receive the vaccine because of the risk of severe illness that can happen while the immune system is still developing.

When are these vaccine administered during the year?
     Influenza Vaccine:  The Center for Disease Control and Prevention (‘the CDC’) recommends getting the influenza vaccine by the end of October.  However, benefit might occur if the vaccine is given as late as January  We all see pharmacies advertising in September and even late August to get the vaccine as early as then.  Protective antibody levels generally take two weeks to develop after vaccination.  In our area, outbreaks of influenza infections most commonly peak between December and February.  Since protective antibody levels slowly but gradually decline over many months, having the higher antibody levels coincide with the most likely time of the year of flu epidemics would seem to be best.  I typically tell patients that late October is perhaps the optimal time of the year to receive the influenza vaccine.
     Pneumococcal Pneumonia Vaccine:  There is no recommendation about a specific time during a year to receive the pneumococcal pneumonia vaccine.

What are the different forms of the influenza vaccine and the pneumococcal pneumonia vaccine?
     Influenza Vaccine:  There are two broad categories of influenza vaccines.  The trivalent vaccine contains two variations of the influenza type A virus and one form of the influenza type B virus.  The quadrivalent vaccine contains two variations of the influenza type A virus and two forms of the influenza type B virus.  Recent expert opinion recommends receiving the quadrivalent vaccine when it is available.
     There is also a high dose form of the influenza vaccine that contains four times the amount of the standard dose. The high dose vaccine is targeted for people 65 years and older    because the aging process decreases the body’s ability to make a good immune response and a higher amount of the inactivated vaccine can be more likely to stimulate the immune system.
     Another option for maximizing the immune response to the influenza vaccine when one is 65 years and older is to use an adjuvanted influenza vaccine product called ‘FLUAD.’
     You may be aware of a form of the influenza vaccine that is sprayed into the nose called FluMist and has been indicated for those between ages 2 and 49.  The CDC no longer recommends receiving this form of the vaccine because of concern about its effectiveness.
     Pneumococcal Pneumonia Vaccine:  There are two types of pneumococcal vaccines.  Pneumovax 23 contains the 23 most common subtypes of the bacteria based on the type of bacterial wall.  Prevnar 13 contains the 13 most common subtypes of the bacteria that cause the most pneumococcal disease; it is also chemically linked to a nontoxic protein that is almost identical to diphtheria toxin and can especially stimulate the immune system.  There is a recommended schedule from the CDC on when to receive Prevnar and Pneumovax, depending on the age of the person and whether certain medical conditions are present.

How long is the effect of the influenza vaccine and the pneumococcal pneumonia vaccine? 
     Influenza Vaccine:  Protective antibody levels for the influenza vaccine are considered to be at high levels for at least 3 months and slowly decrease with time.
     Pneumococcal Pneumonia Vaccine: The answer is not a straightforward one.  When health adults over the age of 50 receive the Pneumovax 23 vaccine, antibody levels decline rapidly over a 1-2 year period and are at low levels for 10 or more years.  However, the CDC  reports that the effectiveness of Pneumovax did not decline at seven or more years after receiving the vaccine.  Theoretically, Prevnar should seem to cause a more persistent response by the immune system. But, studies show that the antibody activity one year after vaccination was identical in those who received Pneumovax and those who received Prevnar.

How well does each vaccine work?
     Influenza Vaccine:  The CDC reports that the risk of influenza viral illness is reduced by between 40% and 60%.  In general, current flu vaccines tend to work better against influenza type B and and one of the types of influenza A.
     Pneumococcal Pneumonia Vaccine:  The largest study of Prevnar is from the Netherlands, and it showed that Prevnar had approximately 45% effectiveness in preventing pneumococcal pneumonia.  Pneumovax studies seems to indicate an approximately 50% reduction in risk for developing pneumococcal pneumonia. However, Prevnar and Pneumovax have an even higher likelihood of preventing pneumococcal disease that is invasive at a normally sterile site in the body.

What are the side effects of each vaccine?
     Influenza Vaccine:  With any vaccine, the most common side effects are redness, soreness or swelling at the site of the injection.  However, we either have or known someone who has developed what seemed to be the flu after receiving the influenza vaccine.  The scientific explanation is that since the influenza vaccine is inactivated, it can’t be infectious.  A low-grade fever and muscle aches can happen and last typically 1-2 days.  But these are considered to be considerably less severe than the symptoms caused by actively replicating viral particles.
     Serious reactions, such as the paralytic illness of Guillain-Barre Syndrome, are very rare— with a risk estimated by the CDC to be one in a million.  Skin testing with influenza vaccine prior to giving the vaccine in patients with egg allergy is no longer advised.  But, skin testing with the influenza vaccine is still advised if the person previously had an allergic reaction to an influenza vaccine.
     Pneumococcal Pneumonia Vaccine: Injection site pain from Pneumovax can occur in approximately 60% of patients, injection site swelling from it occurs in about 20% of patients and injection site redness from it occurs in about 15% of patients.  If these effects occur, they should last for less than 72 hours.  Fever and muscle aches can occur but less commonly.  Prevnar can cause similar symptoms in comparable percentages.

     Any decision about one’s health must balance benefits and risks.  To paraphrase a saying we are familiar with, risk is in the eye of the beholder. If you have a chronic health condition or a weakened immune system, receiving the ‘flu shot’ and the ‘pneumonia shot has the strong benefit of avoiding complications that could include long-term illness and hospitalization.  If you don’t have a chronic medical illness or weakened immune system, getting these vaccines has the benefit of reducing the possibility that you’ll pass the infection to your loved ones.  These benefits are most worthwhile ones to consider.