Scientific Success Story – Prevnar

In 2000, Wyth Pharmaceuticals released the first generation of the vaccine Prevnar (PCV7), now PCV13. Competing vaccines include Synflorix® (GlaxoSmithKline), PNEUMOVAX® 23 (Merck), and PNEUMO 23® (Sanofi Pasteur SA).

Streptococcus pneumoniae (pneumococcus) remains a leading cause of serious illness, including bacteremia, meningitis, and pneumonia among children and adults worldwide. It is also a major cause of sinusitis and acute otitis media. The death rate varies between 5-7% of those with positive pneumococcus serotypes.

Some groups of people are at higher risk including those with chronic medical conditions (liver, heart, lung or kidney disease, diabetes), weak immune systems (cancer, HIV infection), those without a spleen, smokers, alcoholics, the very young and those older than 65 years. In the past, outbreaks occurred among people who were homeless, crack cocaine users and injection drug users.

It can be spread by coming in contact with spit (saliva) or nose droplets from infected people. This can happen by sharing things like cigarettes, eating utensils or crack pipes, kissing or when an infected person coughs or sneezes on you.

Pneumococcal infections are a major cause of morbidity and mortality worldwide and pneumonia is the most common cause of pneumococcal-attributed death. Each year, an estimated 1 million children under five years of age die due to S. pneumoniae respiratory infections, most in developing countries. In Europe and the United States (US), pneumococcal pneumonia is the most common community-acquired bacterial pneumonia, estimated to affect approximately 100 of every 100,000 adults each year. Bacteremia affects approximately 15 to 19 of every 100,000 adults and meningitis affects about 1 to 2 of every 100,000 adults each year.

In Canada between 2005 to 2008, incidence rates (per 100,000 population per year) of IPD were 26.6 among infants less than 1 year of age, 16.9 among children 1 to 4 years, and 20.4 among adults 60 years of age and older. Children under 1 year of age accounted for 3% of cases, those aged 1 to 4 years accounted for 8%, and adults 60 years of age and older accounted for 40% of IPD cases.

The efficacy of the vaccines is clear:

Pneu-C-7 vaccine efficacy is 89% to 97% against IPD due to vaccine serotypes. Pneu-C-7 vaccine provides a 54% reduction in AOM and a 20% reduction in tympanostomy tube placement due to vaccine serotypes.

Pneu-P-23 vaccine efficacy is more than 80% against IPD among healthy young adults and ranges from 50% to 80% among the elderly and in high-risk groups.

Efficacy is reduced in certain groups, and indicates the need for vaccine levels to be high enough to develop herd immunity in a population.

Immunogenicity and efficacy are decreased in certain groups at particularly high risk of pneumococcal infection, such as persons with renal failure, sickle cell anemia, or impaired immune responsiveness, including HIV infection. Following immunization with Pneu-P-23 vaccine, antibody levels decline after 5 to 10 years and decrease more rapidly in some groups than others. The duration of immunity is not known.

Matthew Herper has an article in Forbes Magazine with graphs and some commentary on the decrease of some variants and the rise of others. It is important to note that even with the rise in these variants, the overall effect has been extremely positive. The original article appeared in the Oxford Journal of Infectious Disease and concluded:

Dramatic reductions in IPD after PCV7 introduction in the United States remain evident 7 years later. IPD rates caused by serotype 19A and other non-PCV7 types have increased but remain low relative to decreases in PCV7-type IPD.

Prevnar 13 is part of the current vaccine schedule for Prince Edward Island. As a note, the schedule I linked to is based on the birth date of my grandson.

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