When Children Get the Pneumococcal Vaccine, Adults Benefit, Too
—New information from Germany confirms that vaccinating children for pneumococcal disease has a protective effect on adults. But don’t count on the kids—adults need their own vaccinations, as well.
In Germany, after the introduction of the 7- and 13- valent pneumococcal conjugate vaccines (PCVs) for children, invasive pneumococcal disease (IPD) cases among adults decreased due to the indirect protection vaccinations provide to the unvaccinated population. Additionally, the serotypes responsible for IPD did not significantly vary throughout Germany.1
However, some serotypes not covered by the vaccines—particularly serotype 3—were still present in the adult population, and accounted for many cases of IPD. Despite a 1998 recommendation in Germany for adults to receive the 23-valent pneumococcal polysaccharide vaccine (PPV23), uptake historically has been low.1,2 A recent study in Germany showed, for example, that only approximately 25% of adults ≥60 years had received a PCV.3 Thus, IPD remains prevalent in this group.1,2
Recently, vaccines for adults offering protection against 15 or 20 serotypes were approved by the US Food and Drug Administration and European Medicines Agency, with the 15-valent PCV also being approved for use in children.4,5 The PCV20 recently replaced PPV23 as the recommended pneumococcal vaccine for adults, with recommendations for vaccinations especially in at-risk and high-risk groups.1
To understand the impact of the new PCVs, the authors of a recent study examined prevalence and distribution of IPD serotypes in adults in Germany. Their goal was to collect data for informed decision making for vaccination recommendations, as well as for the manufacture of future vaccinations.
The investigators, who are based at the Department of Epidemiology of Microbial Diseases, Yale School of Public Health, Yale University, New Haven, Connecticut, and at the German National Reference Center for Streptococci in Aachen, Germany, published their findings online in the Journal of Infectious Diseases.1
The demographics and serotypes
The authors looked at the cases of IPD by age (18-40, 40-59, and ≥ 60 years of age) and by serotype, over 3 time periods (the pre-PCV era between 2003-2006, the 4-dose infant PCV era between 2007-2014, and the 3-dose infant PCV era between 2015-2018).1
Serotypes were grouped by vaccine coverage (“PCV7 vaccine-type” for serotypes 4, 6B, 9V, 14, 18C, 19F, and 23F; “PCV13 vaccine-type” for the PCV7 serotypes plus 1, 3, 5, 6A, 7F, and 19A; “PCV15 vaccine-type” for the PCV13 serotypes plus22F and 33F; and “PCV20 vaccine-type” for the PCV15 serotypes plus 8, 10A, 11A, 12F, 15B, and 15C).1
Rates of IPD by age and serotype
Over the entire period, 69.7% of cases occurred in individuals ≥ 60 years of age. In fact, the prevalence of cases of IPD in people in this age group has more than doubled since 2007.1
In 2006, after the introduction of the 7-valent vaccines for children, approximately 75% of cases of IPD in adults ≥ 60 years of age were secondary to PCV13 serotypes. Once the PCV13 was introduced, by 2018, the rate decreased to approximately 30%. Other than serotype 3, all other serotypes included in PCV13 decreased substantially in adults once PCV13 was widely used in the pediatric population (the end of 2009).1
In 2018, the majority of IPD cases in Germany were caused by serotypes covered by PCVs (31% by PCV13 serotypes, 41% by PCV15 serotypes, and 67% by PCV20 serotypes). Of the specific serotypes, serotype 3 comprised 21% of adult IPD in 2018, while serotypes 8, 12F, and 22F comprised approximately 30% of IPD more recently. Serotype 3 is also concerning because it is the most likely serotype to cause non-bacterial pneumonia.1
In summary…
The authors concluded that improving vaccine uptake in adults is key. “PCV use in infants clearly correlates with a substantial reduction in the prevalence of vaccine-type IPD among adults,” they wrote. “However, IPD still represents a substantial burden of disease, and it is important to continue to monitor trends in IPD prevalence. A vaccination strategy that addresses the disease burden of the full population, combined with ongoing efforts to improve vaccine uptake in older adults will be essential to reduce pneumococcal disease burden across the lifespan.”1
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