New Pneumococcal Vaccines: Important Facts to Know
The next generation of pneumococcal vaccines is here, offering new vaccine options for physicians to protect patients from a disease that still sends about 1.3 million people in the U.S. to emergency rooms each year. While welcome, these new vaccines include overlapping serotypes and recommended target groups, which may make clinical decision-making more confusing.
The History of the Pneumococcal Vaccine
The first pneumococcal vaccine, Pneumovax 14, was approved for use in the United States in 1977. It was a polysaccharide vaccine that contained 14 different strains of streptococcus pneumoniae—of which there are about 100 different serotypes. That first vaccine was replaced in 1983 by another polysaccharide vaccine that contained even more serotypes, Pneumovax 23, PPSV23, which covers 23 strains accounting for most cases of invasive disease—including bacterial pneumonia, bacteremia, and meningitis—and is still in use today for some patient populations.
Science marched on, and in 2000, a new, structurally distinct “conjugate” vaccine was approved, Prevnar 7, PCV7, followed in 2008 by PCV13, which is still given as part of routine childhood vaccinations and to adults with additional risk factors or indicators.
Conjugate vs Polysaccharides
Conjugate vaccines are more robust than the polysaccharide vaccine. They prompt a stronger and more lasting immune response, but they cover fewer serotypes. So, to assure the broadest coverage and strongest immune response, the Centers for Disease Control and Prevention (CDC) had recommended PCV13, a conjugate vaccine, for all children to give long-lasting and robust coverage of the most common strains. For adults 65 and older, who suffer 80% of invasive pneumococcal disease, PPSV23, remained the recommended vaccine, as it covers a greater number of bacterial strains than the conjugate PCV13.
But these recommendations have caveats. For persons 2 and older with certain medical conditions, such as heart disease or diabetes, both vaccines are recommended, with the conjugate vaccine given first, followed by PPSV23. In adults 65 and older, if doctor and patient choose, both vaccines also can be given, once again with the conjugate first followed by the broader polysaccharide, one year apart.
New Coverage, New Options
In October 2021, the Advisory Committee on Immunization Practices (ACIP), an expert panel of the Centers of Disease Control and Prevention (CDC), approved two new conjugate vaccines, PCV15, made by Merck, and PCV20, made by Pfizer.
“We were already giving PCV13 followed by PPSV23, and now we have new kids on the block,’’ says Dr. Wanda Filer, Chief Medical Officer at VaxCare. “The new recommendation is PCV 15 plus PPSV23, or PCV 20 alone. You can do just the PCV 20 and get a strong response against the 20 serotypes in the vaccine, but three strains will remain uncovered.’’
While Prevnar13 is approved for children and adults, she says, the new vaccines—Merck’s PCV 15, called Vaxneuvance, and Pfizer’s Prevnar 20—are for adults only, at least until pediatric studies are reported, possibly within a year. This may add to the complexity of recommendations.
We were already giving PCV13 followed by PPSV23, and now we have two new kids on the block: PCV 15 plus PPSV23, or PCV 20 alone.
Results of those studies are eagerly anticipated, especially given the significant public health impact seen with the first wave of childhood vaccination to prevent pneumococcal infection, Dr. Filer says. “Once we started immunizing children against pneumococcal in 2000, it became clear the vaccine was highly effective,’’ she says. “Rates of illness in children improved dramatically, plunging 90% since 2008, according to the CDC, and we don’t see nearly the number of ear infections we used to.”
But the impact went beyond children’s health, resulting in a spillover effect that also has reduced the rate of disease in adults, she adds. “The vaccine lowered the number of bacteria in children’s noses, so when they hugged their grandparents and teachers, they were less likely to pass along infection,’’ she says. With routine vaccination of children, “the actual amount of pneumococcal disease in older adults dropped precipitously,’’ she says. Because of that, in 2019, the ACIP changed its recommendation for people 65 and older from a two-vaccine regimen to “shared decision making’’ on whether to administer PCV13 in addition to PPSV23.
All the changes can be perplexing for patients and clinicians alike, says Dr. Filer. “As a physician,’’ she says, “it can be incredibly confusing with several different pneumococcal vaccines in the refrigerator. We find it is not uncommon in a busy practice for somebody to pull out the wrong vial.’’
The ACIP always strives to balance public health with the economic realities associated with the cost of new vaccines, Dr. Filer says, and as new data comes in, more changes may be coming. Stay tuned.
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