Centers for Disease Control and Prevention (CDC) Direct and indirect effects of routine vaccination of children with 7-valent pneumococcal conjugate vaccine on incidence of invasive pneumococcal disease--United States, 1998-2003. MMWR Morb Mortal Wkly Rep. 2005 Sep 16;54(36):893-7.
Mahon BE, Hsu K, Karumuri S, Kaplan SL, Mason EO Jr, Pelton SI; U S. Pediatric Multicenter Pneumococcal Surveillance Group; Massachusetts Department of Public Health Epidemiologists. Effectiveness of abbreviated and delayed 7-valent pneumococcal conjugate vaccine dosing regimens. Vaccine. 2006 Mar 24;24(14):2514-20. Epub 2005 Dec 27.
Mera RM, Miller LA, Daniels JJ, Weil JG, White AR Increasing prevalence of multidrug-resistant Streptococcus pneumoniae in the United States over a 10-year period: Alexander Project. Diagn Microbiol Infect Dis. 2005 Mar;51(3):195-200.
Murray D, Jackson C A conjugate vaccine for the prevention of pediatric pneumococcal disease. Mil Med. 2002 Aug;167(8):671-7. Review.
Yu S, Yao K, Shen X, Zhang W, Liu X, Yang Y Serogroup distribution and antimicrobial resistance of nasopharyngeal isolates of Streptococcus pneumoniae among Beijing children with upper respiratory infections (2000-2005). Eur J Clin Microbiol Infect Dis. 2008 Aug;27(8):649-55. doi: 10.1007/s10096-008-0481-y. Epub 2008 Mar 18.
Comparison of the Immunogenicity of the 3+1 Schedule and the 2+1 Schedule of 7-valent Pneumococcal Conjugated Vaccine in Young Chinese Infants
Interventional studies are often prospective and are specifically tailored to evaluate direct impacts of treatment or preventive measures on disease.
Observational studies are often retrospective and are used to assess potential causation in exposure-outcome relationships and therefore influence preventive methods.
Expanded access is a means by which manufacturers make investigational new drugs available, under certain circumstances, to treat a patient(s) with a serious disease or condition who cannot participate in a controlled clinical trial.
Clinical trials are conducted in a series of steps, called phases - each phase is designed to answer a separate research question.
Phase 1: Researchers test a new drug or treatment in a small group of people for the first time to evaluate its safety, determine a safe dosage range, and identify side effects.
Phase 2: The drug or treatment is given to a larger group of people to see if it is effective and to further evaluate its safety.
Phase 3: The drug or treatment is given to large groups of people to confirm its effectiveness, monitor side effects, compare it to commonly used treatments, and collect information that will allow the drug or treatment to be used safely.
Phase 4: Studies are done after the drug or treatment has been marketed to gather information on the drug's effect in various populations and any side effects associated with long-term use.