Aaby P, Whittle H, Benn CS Vaccine programmes must consider their effect on general resistance. BMJ. 2012 Jun 14;344:e3769. doi: 10.1136/bmj.e3769.
Anderson EJ, Webb EL, Mawa PA, Kizza M, Lyadda N, Nampijja M, Elliott AM The influence of BCG vaccine strain on mycobacteria-specific and non-specific immune responses in a prospective cohort of infants in Uganda. Vaccine. 2012 Mar 9;30(12):2083-9. doi: 10.1016/j.vaccine.2012.01.053. Epub 2012 Jan 31.
Behr MA BCG--different strains, different vaccines? Lancet Infect Dis. 2002 Feb;2(2):86-92. Review.
Behr MA Correlation between BCG genomics and protective efficacy. Scand J Infect Dis. 2001;33(4):249-52. Review.
Biai S, Rodrigues A, Nielsen J, Sodemann M, Aaby P Vaccination status and sequence of vaccinations as risk factors for hospitalisation among outpatients in a high mortality country. Vaccine. 2011 May 9;29(20):3662-9. doi: 10.1016/j.vaccine.2011.03.016. Epub 2011 Apr 6.
Penfold S, Willey BA, Schellenberg J Newborn care behaviours and neonatal survival: evidence from sub-Saharan Africa. Trop Med Int Health. 2013 Nov;18(11):1294-316. doi: 10.1111/tmi.12193. Epub 2013 Sep 24. Review.
Ritz N, Curtis N Mapping the global use of different BCG vaccine strains. Tuberculosis (Edinb). 2009 Jul;89(4):248-51. doi: 10.1016/j.tube.2009.03.002. Epub 2009 Jun 18.
Ritz N, Hanekom WA, Robins-Browne R, Britton WJ, Curtis N Influence of BCG vaccine strain on the immune response and protection against tuberculosis. FEMS Microbiol Rev. 2008 Aug;32(5):821-41. doi: 10.1111/j.1574-6976.2008.00118.x. Epub 2008 Jul 9. Review.
Wardlaw T, You D, Newby H, Anthony D, Chopra M Child survival: a message of hope but a call for renewed commitment in UNICEF report. Reprod Health. 2013 Dec 11;10:64. doi: 10.1186/1742-4755-10-64.
Evaluating the Effect of Different BCG Strains on Early Life Hospital Admissions in Guinea-Bissau: A Randomised Trial
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.