In William Osler’s day (turn of the 20th century), pneumonia was called “the old man’s friend,” because it took the elderly away quietly and with relatively little fuss. It was most often caused by the pneumococcal organism, now called Streptococcus pneumoniae. When penicillin came on the scene in the mid 20th century, there was at last a treatment for pneumonia with this organism, but soon resistant strains developed. S. pneumoniae is a frequent resident of the human respiratory tract and usually causes no problems. But if it gets into the wrong place it can also cause sepsis, otitis media, meningitis, sinusitis, peritonitis and arthritis. And it can also take advantage of ground prepared for it by a viral infection. It is the most prevalent secondary bacterial infection complicating influenza and a major cause of mortality in flu cases. Fortunately there is something we can do to prevent that: vaccination. The vaccine isn’t to the flu virus but to many of the strains (called serotypes) of S. pneumoniae. CDC has just issued interim guidance on the use of pneumococcal vaccine during a flu pandemic. In case you haven’t noticed, we are having a flu pandemic at the moment:.
Influenza predisposes individuals to bacterial community-acquired pneumonia. During the 20th century influenza pandemics, secondary bacterial pneumonia was an important cause of illness and death and Streptococcus pneumoniae (pneumococcus) was reported as the most common etiology. Severe pneumococcal pneumonia associated with inter-pandemic influenza also has been reported, and S. pneumoniae remains a leading cause of vaccine-preventable illness and death in the United States. The current novel influenza A (H1N1) outbreak is evolving rapidly, and CDC continues to compile key information regarding risk of influenza, severity of illness and attack rate of secondary bacterial pneumonia among influenza patients. (CDC guidance document)
I got the pneumovax vaccine about a year ago. At the time I got it because I was in the recommended group (over 65), but now with swine flu amongst us CDC has extended its recommendation of the single dose 23-valent pneumococcal vaccine (of which Pneumovax is an example) to anyone over the age of 2 with a high risk condition. You can see their list of conditions in the Table at the bottom of the page here, but it includes things like COPD, congestive failure and diabetes. It also includes adults who smoke or have asthma, so this extends the recommendation to perhaps a third of all adults. If you aren’t in these categories and are between the ages of 2 and 64, CDC is not saying you should get the pneumococcal vaccine to protect you from pneumococcal pneumonia secondary to flu — but I am. As far as I know there is no shortage of this vaccine and it is very effective and seems equally safe. You only need to get it once.
Most children now get another pneumococcal vaccine that covers the 7 most common serotypes for the under 5 age group. This was mainly to protect them against middle ear infections and bacterial meningitis, but in a flu pandemic where children are at high risk it would partially protect them from pneumonia. Unfortunately there are other causes of secondary bacterial pneumonia not covered by the vaccine implicated in pediatric flu mortality (e.g., MRSA staph infections), but this removes a chunk of them.
The pneumococcal vaccines (and another childhood vaccine against Haemophilus influenzae type B, a different bug) are extremely effective. Given the severe cases reported among Manitoba’s First Nation communities, it’s of some interest that S. pneumoniae infections have been a special problem among the Alaskan Native population, where it is a leading causes of meningitis, pneumonia, middle ear infection and sinusitis. There the vaccine has had notable success:
Although polysaccharide pneumococcal vaccines have been available for many years, they are not effective in young children. In 2000, a 7-valent protein-polysaccharide pneumococcal vaccine (Prevnar®), which is effective in young children, was licensed by the Food and Drug Administration. In January 2001, the State of Alaska made this vaccine available for children < 5 years of age. Two years after the introduction of vaccine, rates of invasive pneumococcal disease among Alaska Native children caused by serotypes in Prevnar® declined by 90%. This suggests that vaccination of young children might be the key to decreasing rates of disease in this population. (CDC; cites omitted)
We don’t know exactly why influenza infection predisposes to secondary bacterial infections (see some good discussion of the biology over at Vincent Racaniello’s excellent Virology Blog). The influenza virus itself can cause a serious pneumonia (primary viral pneumonia), also a significant cause of mortality when it occurs. Then there is the dysregulation of the immune response called a cytokine storm. So the flu virus can do mortal damage in a number of different ways.
The pneumococcal vaccine will likely prevent one of the more common serious complications. Ask your doctor to give it to you