A Swedish researcher has found that the vaccine given to children to immunize against serious pneumococcal disease does not offer full protection.
Currently there are two types of active vaccine—polysaccharide vaccines, which protect against more types of pneumococcal bacteria but cannot be given to children under the age of 2, and conjugated vaccines, which can be given to infants but protect against fewer types.
Erik Backhaus, an infection specialist at Skövde Hospital, who conducted the research for his doctoral thesis at the University of Gothenburg’s Sahlgrenska Academy, looked at all cases of serious pneumococcal disease in children and adults in the Västra Götaland region of Sweden between 1998 and 2001. He found that the latest conjugated vaccines theoretically offer protection against around 70% of infections.
“But around 95% of infections are caused by serotypes covered by the polysaccharide vaccine,” said Backhaus. “This vaccine cannot be administered to children under 2 years of age, which means that it cannot be used in those who need it most.”
In the worst case, the bacteria cause serious disease from which around 10% of patients die within a month of diagnosis. Backhaus found that the risk of dying depends partly on age and partly on underlying medical conditions, but also that the risk is higher for men than women. Interestingly there are also geographical variations: fewer serious pneumococcal infections are diagnosed in people over the age of 80 in the Gothenburg area than in other parts of the Västra Götaland region.
“This may be due to different routines for admitting patients from nursing homes to hospital and how often blood cultures are performed,” he explained.
Backus also found that over the past 45 years the number of cases of severe pneumococcal disease diagnosed in the Gothenburg area has tripled from 5 to 15 cases per 100,000 inhabitants per year. This is probably because many more blood cultures are performed these days, meaning that more cases are detected.
Source: University of Gothenburg, The Sahlgrenska Academy