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A new clinical trial shows that a vaccine made by Pfizer Inc. may reduce the risk of heart attack by half or more compared with placebo. According to data published online on Monday in JAMA Network Open, Pfizer’s Prevnar 13 vaccine, or Pneumovax 13, is also associated with lower rates of seizures in children and teenagers compared with the placebo, or Inactivated Polio Vaccine (IPV).
According to the study, there were 31.5 deaths in both the group of vaccinated subjects with a 95% confidence interval (CI) between 12 and 17. The group of patients without the vaccine had 16.6 deaths.
Based on the findings, cardiologist Dr. Steven Nissen, chief of cardiology at the Cleveland Clinic and an editor of JAMA Network Open, said, “These are impressive results.”
He explained that in older adults, a number of the side effects associated with the vaccine are considered mild. However, patients can experience severe complications, such as hypertension and painful neutropenia, from a multi-drug reaction. Therefore, in an effort to address the potential risks from the vaccine, Nissen said that physicians have to ensure that patients take the antigens that they are supposed to.
“There’s a lot of burden to having these immunizations for every single patient in the Medicare population,” he said.
Prevnar 13 is one of the world’s most widely prescribed vaccines. A review published in JAMA in 2014 said that more than 83 million doses of the vaccine were distributed globally. In the US, the CDC estimated that between 2009 and 2015 more than 5.1 million doses of the vaccine were administered to children and adolescents ages 19 to 64.
However, vaccinations have been called into question recently. Just last week, the CDC warned that a recent study involving real patients, not the researchers, raised questions about Prevnar 13’s safety.
The trial was sponsored by Pfizer and conducted by Merck & Co. The results were pooled and checked by Roberta Mendelson, a professor of pediatrics at the University of California, San Francisco. Her study also found that Novartis’ Cervarix vaccine reduced the risk of hospitalization by 43%. The Cervarix vaccine is not recommended for children younger than 6 months of age. It is recommended for all children through age 22, according to the CDC.
Although she acknowledged the risks associated with vaccines, Mendelson said, “I believe that immunization is the best and most cost-effective way to vaccinate individuals who might be at higher risk for adverse events from infection with various communicable diseases.”
Liz Peek, a medical writer and oncologist at the University of California, San Francisco, explained that this new trial is the second time that Prevnar 13 has had findings that were encouraging. She explained that in 2012, “that vaccine was shown to reduce the risk of morbidity and mortality by half, but not hospitalizations.” Peek was the lead author of the first study and was also editor of JAMA in 2012.
However, she said, “we don’t have all the answers yet,” and it’s important to recognize that Prevnar 13 is a pre-licensure vaccine for only a few diseases. She pointed out that the potential benefits outweigh the side effects associated with the vaccine, and she praised these latest findings.
Dr. Len Lichtenfeld, deputy chief medical officer for the American Cancer Society, also commended the study, but emphasized that “it was a single arm study, so the results don’t mean Prevnar 13 prevented all the problems that were seen in the trial.” He added that more work needs to be done to validate this vaccine’s benefits and validate the findings in other studies.
“I would consider Prevnar 13 a gold standard,” he said. “The downside of this vaccine is that it causes chronic immunity because it’s a highly formulated vaccine. But if you take the benefit we know it provides over time, against an array of different infectious diseases, I think this is one of the safest vaccines we have.”
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