CDC warns about rise in serious pneumococcal disease

Nov 25, 2009 (CIDRAP News) – In a worrisome but not unexpected pandemic-related development, the US Centers for Disease Control and Prevention (CDC) said today that it is seeing a spike in serious pneumococcal disease, particularly in younger patients.

Anne Schuchat, MD, director of the CDC's National Center for Immunization and Respiratory Diseases, told reporters at a press briefing that the CDC is seeing an increasing number of invasive pneumococcal disease cases around the country, but the numbers were particularly high in Denver at a time when pandemic H1N1 activity was peaking in the area.

Over the past 5 years the Denver area averaged 20 pneumococcal disease cases in October, but this year the area recorded 58, and most were in adults between the ages of 20 and 59, many of whom had underlying medical conditions.

Health officials expect to see more pneumococcal disease when seasonal flu circulates, but the infections typically strike people who are older than 65. In past pandemics secondary bacterial pneumonia infections, particularly those involving Streptococcus pneumoniae, frequently contributed to illnesses and deaths.

Reminder for pneumococcal vaccine
Schuchat said the rise in pneumococcal disease is a stark reminder for high-risk groups to get the pneumococcal vaccine.

The CDC recommends the vaccine for several high-risk groups, but uptake is low. Only about 25% of adults in high-risk groups who are younger than age 65 have received the vaccine. The CDC's vaccine advisory group recently added people with asthma and smokers to the list of those who should receive the pneumococcal vaccine.

About 75% of Colorado's invasive pneumococcal disease cases were caused by serotypes that are included in the pneumococcal polysaccharide vaccine, consistent with what the CDC sees during nonpandemic years. About two thirds of the patients had at least one indication to receive the vaccine but had not been vaccinated.

Of the 10 patients with confirmed pandemic H1N1 infections, 7 had high-risk conditions, but only 1 had received the vaccine. Others were tested for the virus, but the timing of the testing made it difficult to document influenza. Other patients reported that they had flu-like symptoms before they got sick with pneumococcal infections.

The CDC said it is working with state and local officials to collect more information on pneumococcal disease cases. Colorado is one of 10 states that takes part in its Active Bacterial Core (ABC) surveillance system for pneumoccocal and other bacterial diseases.

Over the past several months, CDC officials have urged healthcare workers to make sure high-risk groups receive the pneumococcal vaccine as the country faces a long flu season that could include waves of pandemic and seasonal influenza. On Nov 10 Schuchat sent a letter to providers urging them to make sure patients with indications receive the vaccine.

Increase not surprising
Andrew Pavia, MD, chief of pediatric infectious diseases at the University of Utah, told CIDRAP News that an increase in bacterial pneumonia, though worrisome, is expected during any influenza epidemic or pandemic. He noted that several studies have described how the infections parallel viral infections, particularly seasonal flu.

Physicians are particularly wary of methicillin-resistant Staphylococcus aureus (MRSA) pneumonia infections this flu season, because they are more severe and deadly than pneumococcal pneumonia infections.

However, Pavia cautioned that it is too early in the season to see big increases in pneumonia cases. "Remember that it is hard to document bacterial pneumonia, and surveillance systems are not well designed to detect it," he said. "I suspect that the relative lack of reports of bacterial pneumonia in the spring may have been artifacts."

He pointed out that, for example, ABC sites didn't experience major waves of pandemic H1N1 illnesses in the spring and that the ABC surveillance sites do not include four of the hardest-hit US cities: New York City, Salt Lake City, Seattle, and Chicago.

Aaron DeVries, MD, a medical epidemiologist with the Minnesota Department of Health, said Minnesota has not seen a larger-than-expected number of bacterial pneumonia cases. Minnesota is one of the states that takes part in the CDC's ABC surveillance system. "We've always been concerned about bacterial coinfections with influenza, but it's not occurring to the degree that we were all concerned about."

He said pneumococcal vaccination can provide powerful benefits, adding that vaccinating infants has reduced illnesses in not only those who are vaccinated but also in those who didn't receive the vaccine.

Because the indications for adults have broadened in the past few years, he said, many people may not be aware that they should receive the vaccine.

DeVries said that although most healthcare providers know which groups are at highest risk and should receive the pneumococcal vaccine, such as patients who have had splenectomies, even they could benefit from more education about the latest recommendations from the CDC's vaccine advisory group.

Vaccine supply grows by 7 million doses
Schuchat told reporters that since last Friday, about 7 million more doses of pandemic H1N1 vaccine have become available for states to order. The total now stands at 61.2 million doses. She added that a little less than 25% of the vaccine total is the live attenuated vaccine (LAIV) in the nasal-spray form.

"Vaccination efforts will really step up as we head into December," she said. Several states have major vaccine campaigns planned for after Thanksgiving, she added.

Safety data reassuring
As the number of people receiving vaccine grows steadily, the CDC now has more information on vaccine safety and adverse events to assess. "So far everything we've reviewed is very reassuring," she said.

Patterns and types of events seem to mirror what officials have seen with the seasonal flu vaccine. Schuchat said that 94% of reports coming into the Vaccine Adverse Event Reporting System (VAERS) are not serious and consist mainly of mild symptoms such as arm soreness or tenderness. "We've looked at severe allergic reactions, and they are not showing up more commonly than we'd expect," she said.

The CDC has received 10 reports of potential Guillian-Barre syndrome (GBS), but she said the number of reports compared to the number of pandemic H1N1 vaccine doses administered is not at all notable. GBS is a temporary paralytic condition that was linked to the United States' 1976 swine flu vaccine.

See also:

CDC background information on invasive pneumococcal disease and vaccine safety

Nov 10 CDC letter to providers about pneumococcal vaccination

Sep 28 CIDRAP News story "CDC cites bacterial infections in some H1N1 deaths"

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