Babies in this country and in Europe are given several immunizations during the first two years of life, and one vaccine that has made a big dent in infant mortality rates is PCV7 – the 7-valent pneumococcal conjugate vaccine. A study coming out in mBio this week shows that the vaccine cuts down on invasive pneumococcal disease by 80% in infants under two years old. But that’s not the surprising part of the study. The authors also found that, thanks to herd immunity, immunizing babies for pneumococcal disease is helping to keep grandparents out of the hospital.
Historically speaking, people over age 65 have borne the greatest burden from pneumococcal disease, a set of diseases that includes IPD and pneumococcal pneumonia. According to Simonsen et al., once babies were administered the pneumococcal conjugate vaccine, hospitalization rates and deaths resulting from pneumococcal pneumonia among older people plummeted. All together, people in all age groups avoided 700,000 hospital stays between 2000 and 2006 thanks to the pneumococcal vaccine. This means that 90% of the reduction in hospitalizations and deaths were among adults, mostly seniors, who never took the vaccine, indicating that PCV7 has had greater effect through herd immunity than had previously been recognized.