SAN DIEGO — While vaccines have greatly lowered the mortality rate and transmission of pneumococcal disease, this illness – particularly nonvaccine serotypes – remains a major global burden, often causing resistant infections in patients with co-morbidities such as diabetes, said Keith Klugman, MD, PhD, director of the pneumonia program for the Bill and Melinda Gates Foundation.
In a discussion about pneumococcal disease presented at the 55th annual ICAAC ICC 2015, Dr Klugman cited studies that have shown that vaccines greatly reduce the occurrence of invasive pneumococcal disease and pneumonia.1 Additional studies have shown the value of administering the vaccine to children, greatly reducing carriage and therefore transmission in the community,2 and consequently benefiting the older populations that are particularly at risk,3 he said.
“We are beginning to see the regional elimination of certain vaccine types of pneumococcal disease,” he said. If this continues to be the case, Dr Klugman suggested that clinicians may consider changing their vaccine strategy.
“Can we begin to think ‘is it necessary in the U.S. to immunize infants four times against pathogens we are no longer seeing? Can we maintain protection if we identify the children who are the main transmitters,’” Dr Klugman asked. “What if two doses may be able to maintain protection by giving it to the right age of children,” he said, adding that this is a strategy that is currently being studied.
A change in strategy could make the vaccines more affordable and accessible, he said. The strategy could be a particular benefit in poor communities and the poorest countries, where childhood morbidity remains focused, he said.
Additionally, Dr Klugman said, the emergence of non-vaccine serotypes continues to pose a serious challenge to combating pneumococcal disease.
Data show an increase in non-vaccine serotypes of pneumococcal disease in adults with comorbidities, Dr Klugman noted. One specific population in which the problem is pronounced is patients with diabetes. He cited a study 4 showing that the proportion of adults who had a comorbidity and contracted invasive pneumococcal disease actually grew 51% before the introduction of the PCV7 vaccine to 61% after its introduction.
Apart from age, the study found that patients with diabetes now comprise the largest proportion of adults with invasive pneumococcal disease. A continued increase in the prevalence of diabetes among U.S. adults could lead to an increased burden of pneumococcal disease, the study said.
Fortunately there are numerous preventive approaches in development that can address the evolving threat of pneumococcal disease, including a whole cell killed vaccine, Dr Klugman said. He also cited work on proteins now being studied in a phase 3 trial that are broadly protective.
Vast amounts of money is being raised by the Gates Foundation, the United States and other countries to provide vaccines to the poorest of the poor, but additional strategies are needed to address the pneumococcal burden on a global scale, Dr Klugman explained.
1. Anne von Gottberg, Linda de Gouveia, Stefano Tempia, Effects of vaccination on invasive pneumococcal disease in South Africa. N Engl J Med. 2014; 371 (20): 1889.
2. Nontombi Mbelle,1 Robin E. Huebner,1 Avril D. Wasas, Immunogenicity and Impact on Nasopharyngeal carriage of a nonavalent pneumococcal conjugate vaccine. J Infect. Dis. 1999; 180:1171-6
3. Pillishvilli T, Lexau C, Farley MM, Sustained reductions in invasive pneumococcal disease in the era of conjugate vaccine. J Infect Dis. 2010; Jan 1;201(1):32-41.
4. Riyadh D. Muhammad, Reena Oza-Frank, Elizabeth Zell, The epidemiology of invasive pneumococcal disease among high risk adults since the introduction of pneumococcal conjugate vaccine in children. Clin Infect Dis. 2013; 56 (5):e59-e67.