The Centers for Disease Control and Prevention (CDC) began recommending a single dose of varicella vaccine in children aged 1 to 13 years old in 1995. Although the incidence of varicella fell by 90 percent after introduction of the vaccine, there was a high rate of breakthrough varicella illness in immunized children and continuing outbreaks of varicella among children despite high rates of vaccination. Studies also showed that the single-dose vaccine's effectiveness was less than 90 percent. Given the evidence, CDC in 2006 began recommending a second dose of the vaccine for children 4 to 6 years old.
Although data suggest that two doses of varicella vaccine are associated with higher levels of antibody than is one dose, this study is the first to assess the clinical effectiveness of two doses of the vaccine in the general population. Eugene D. Shapiro, MD, and colleagues at Yale University and collaborators at Columbia University conducted active surveillance in an area in Connecticut and discovered 71 cases of varicella in children aged 4 or older. None of the children had received two doses of vaccine, 66 (93 percent) had received one dose, and 5 (7 percent) had received no vaccine.
The investigators then compared the effectiveness of two doses of vaccine versus one dose in a case-control study, using 140 matched controls. The effectiveness of one dose in preventing varicella was 86.0 percent, while the effectiveness of two doses was 98.3 percent. According to Dr. Shapiro, "The odds of developing varicella were 95 percent lower in children who had received two doses of the vaccine compared with those who had received only one."
The results of this study suggest that countries immunizing children with only one dose of varicella vaccine should consider changing to a two-dose regimen. But, the authors emphasized, "There should be continued monitoring of the effectiveness of two doses to assure that its high degree of effectiveness is sustained."
In an accompanying editorial, David W. Kimberlin, MD, of the University of Alabama at Birmingham, agreed with the study authors, noting that this study is the first to evaluate the effectiveness of two doses of varicella vaccine in a "real-world" setting. "The high effectiveness of 98.3 percent found in this investigation supports the programmatic change instituted four years ago," Dr. Kimberlin noted.
1) In this study, the odds of developing varicella (chickenpox) were 95 percent lower in children > 4 years of age who had received two doses of the varicella vaccine compared with those who had received only one dose.
2) Of the 71 cases of varicella noted in the study, none of the subjects had received two doses of vaccine.
3) The effectiveness of two doses of vaccine in protecting against varicella in the study population was 98.3 percent.
NOTE: The study and the accompanying editorial are available online. They are embargoed until 12:01 a.m. EST on Wednesday, Jan. 5, 2011:"Effectiveness of 2 Doses of Varicella Vaccine in Children"
John Heys | EurekAlert!
New study: How does Europe become a leading player for software and IT services?
03.04.2017 | Fraunhofer-Institut für System- und Innovationsforschung (ISI)
Reusable carbon nanotubes could be the water filter of the future, says RIT study
30.03.2017 | Rochester Institute of Technology
The world's highest gain high power laser amplifier - by many orders of magnitude - has been developed in research led at the University of Strathclyde.
The researchers demonstrated the feasibility of using plasma to amplify short laser pulses of picojoule-level energy up to 100 millijoules, which is a 'gain'...
Staphylococcus aureus is a feared pathogen (MRSA, multi-resistant S. aureus) due to frequent resistances against many antibiotics, especially in hospital infections. Researchers at the Paul-Ehrlich-Institut have identified immunological processes that prevent a successful immune response directed against the pathogenic agent. The delivery of bacterial proteins with RNA adjuvant or messenger RNA (mRNA) into immune cells allows the re-direction of the immune response towards an active defense against S. aureus. This could be of significant importance for the development of an effective vaccine. PLOS Pathogens has published these research results online on 25 May 2017.
Staphylococcus aureus (S. aureus) is a bacterium that colonizes by far more than half of the skin and the mucosa of adults, usually without causing infections....
Physicists from the University of Würzburg are capable of generating identical looking single light particles at the push of a button. Two new studies now demonstrate the potential this method holds.
The quantum computer has fuelled the imagination of scientists for decades: It is based on fundamentally different phenomena than a conventional computer....
An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.
We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...
Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.
Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...
24.05.2017 | Event News
23.05.2017 | Event News
22.05.2017 | Event News
29.05.2017 | Earth Sciences
29.05.2017 | Life Sciences
29.05.2017 | Physics and Astronomy