Archive for September, 2012

RV144 vaccine efficacy increased against certain HIV viruses

Thursday, September 13th, 2012 (last updated)

Scientists used genetic sequencing to discover new evidence that the first vaccine shown to prevent HIV infection in people also affected the viruses in those who did become infected. Viruses with two genetic “footprints” were associated with greater vaccine efficacy. The results were published today in the online edition of the journal Nature (http://www.nature.com/nature/journal/vnfv/ncurrent/full/nature11519.html).

“This is the first time that we have seen pressure on the virus at the genetic level due to an effective HIV vaccine,” said Morgane Rolland, Ph.D., a scientist at the U.S. Military HIV Research Program and lead author of the study. The analysis revealed evidence of a vaccine-induced immune response on two sites of Env-V2 region located on HIV’s outer coat. For viruses carrying these two particular signatures, the vaccine efficacy increased to 80 percent.

“These findings reinforce both the RV144 result and the previous study showing that antibodies directed at the V1V2 region reduce the risk of infection. Taken together the work suggests that the Env-V2 region could be a critical target for future HIV vaccines,” noted Col. Jerome Kim, senior author on the study.

“Genetic sequencing is an important and independent assessment of the immune responses induced by the vaccine,” said Paul Edlefsen, Ph.D., a biostatistitian at the Statistical Center for HIV/AIDS Research and Prevention (SCHARP) who co-led the study. Researchers examined HIV genome sequences from 110 volunteers who participated in the Thai HIV vaccine trial, RV144, and who subsequently became infected with HIV. Results indicate that the HIV viruses infecting trial participants were different in persons who received vaccine compared to those who received placebo.

Researchers focused their analysis on the V2 portion of the HIV virus after a study published earlier in 2012 found that antibodies specific to the V1V2 region of the HIV genome correlated with lower risk of infection. This new genetic sequencing study showed that the viruses that broke through or escaped from these immune responses have genetic differences in the same V2 region, indicating that the vaccine exerted pressure in this region.

HIV viruses that escape from antibodies and manage to infect a person have genetic footprints, or mutations, that can prevent them from being recognized by the immune system. These changes can be seen in the genetic sequence of the virus. The research team sequenced more than a thousand full-length viruses to look very carefully at which changes corresponded to “escape” mutations.

“This study underscores the realistic optimism you see in the HIV vaccine research field today. We are making substantive progress in understanding what it will take to develop a more effective HIV vaccine which will ultimately help us end this pandemic.” said Col. Nelson Michael, director of MHRP.

Source:
Medical News Today

Meningitis A in Burkina Faso

Thursday, September 13th, 2012 (last updated)

MenAfriVac, a new vaccine against Meningococcal Meningitis seroptype Nm A, is expected to prevent meningitis epidemics in Africa’s “meningitis belt” of 25 countries that stretch from Senegal in the west to Ethiopia in the east. Hit by epidemics every few years, the meningitis belt accounts for 95 percent of the world’s meningococcal meningitis disease burden. The region’s worst epidemic in recent times, the 1996 epidemic, hit more than 250,000 people in the region, killing 25,000 people and causing residual disability for 50,000 others. Besides the death and disability though, meningitis epidemics have a profound socio-political significance too. Epidemics frighten people away from work and cost large amounts of money to handle. Developed by the Meningitis Vaccine Project, a joint project of PATH and WHO, the vaccine was launched in Burkina Faso in November 2010. MenAfriVac costs less than 50 US cents per dose and is 95 percent effective. The GAVI Alliance is paying the overwhelming majority of costs to roll the vaccine out. If fully funded, GAVI expects to see 236 million people vaccinated with MenAfriVac in all 25 countries of the meningitis belt.

Source:
GAVI Alliance & Immunize Every Child

Flu vaccine is ‘like a seat belt’

Wednesday, September 12th, 2012 (last updated)

Dr. George Vimal, Family Practice doctor at ADC, compares the flu vaccine to a seat belt. Many people say they don’t get the flu and question why they would need the vaccine, but Dr. George says it can help prevent serious complications, much like a seat belt. Hopefully you never need to use it.

Source:
ADCHealth

Publication in The Lancet of world’s first efficacy results of a Dengue vaccine candidate

Tuesday, September 11th, 2012 (last updated)

dengue

Sanofi Pasteur, the vaccines division of Sanofi, announced today the online publication in The Lancet (http://www.thelancet.com/journals/lancet/article/PIIS0140-6736(12)61428-7/fulltext#article_upsell) of clinical study results showing the ability of its vaccine candidate to protect against dengue fever caused by three dengue virus types. The results of the world’s first efficacy study confirm the excellent safety profile of Sanofi Pasteur’s dengue vaccine candidate.

“The complexity of dengue virus infection has hampered vaccine research for decades. This is the first time in 50 years of dengue research that I have seen a vaccine that protected a large group of children from clinical disease caused by dengue viruses. Best yet, the vaccine met the highest safety expectations,” said Dr. Scott Halstead, International Vaccine Institute, Seoul, Republic of Korea. “These results should be a source of hope for millions of parents whose children are at risk of severe dengue, a life-threatening disease which often requires hospitalization.”

The full analysis of vaccine efficacy against each serotype, reflecting real-life conditions (intent to treat analysis) showed vaccine efficacy to be 61.2% against dengue virus type 1, 81.9% against type 3 and 90% against type 4. One of the dengue virus types (serotype 2) eluded the vaccine. Analyses are ongoing to understand the lack of protection for serotype 2 in the particular epidemiological context of Thailand.

“Having worked in the field of dengue research for over four decades, with much of my efforts focused on prevention and control, it is very exciting for me to see a safe vaccine candidate that provides protection against 3 of the four dengue serotypes,” said Professor Duane Gubler, Program on Emerging Infectious Diseases, Duke-NSU Graduate Medical School, Singapore. “Dengue is a major public health concern for over half of the world’s population and is a leading cause of hospitalization and death among children in endemic countries.  Because mosquito control has failed to control this disease, an effective vaccine will be a critical tool that can change the life of millions living in endemic countries. I see this success as the beginning of a new era of effective control.”

According to Dr. Roberto Tapia Conyer, General Director of the Carlos Slim Health Institute, Former Undersecretary of Health in Mexico, “These dengue vaccine results bring a significant promise in the context of the expanding dengue disease burden worldwide and the absence of specific treatment. Work will continue to study this vaccine and the circulation of dengue viruses globally, but in the meantime, the public health community can now formulate the best possible immunization policies and prepare for implementation of vaccination campaigns in countries heavily affected by dengue.”

A feature of dengue epidemiology is that the relative prevalence of virus types in a given area is evolving with time.  Large-scale phase III clinical studies of Sanofi Pasteur’s dengue vaccine candidate are underway with 31,000 children and adolescents in 10 countries in Asia and Latin America. These studies will generate important additional data in a broader population and in a variety of epidemiological settings to define the best conditions to set up vaccination programs in order to protect people at risk of dengue.

Source:
Sanofi Pasteur & The Lancet

Do parents weigh the common good in vaccine choices?

Tuesday, September 11th, 2012 (last updated)

When parents are deciding whether or not to vaccinate their kids, it’s unclear whether the potential benefit or danger to others resulting from their decision is a motivating factor. That could be a gap in education that merits addressing by public health officials, according to a group of Indiana University pediatricians.

Much of the public discussion around vaccination concerns the benefits or risks to an individual child, the researchers wrote in a paper published in the journal Pediatrics.

“There appears to be some parental willingness to immunize children for the benefit of others, but its relative importance as a motivator is largely unknown,” the authors wrote.

While vaccines for infectious diseases protect the person that gets them, they also have benefits for the public at large. When a large proportion of people in an area is protected against a contagious disease, that puts up a kind of firewall against it. Even if a person is unvaccinated – whether by choice, or because they are too young or weak – they can still be protected by this “herd immunity.”

However, herd immunity only works if you have a substantial portion of the herd that’s not susceptible to the disease. The more unvaccinated people there are in a population, the more opportunities there are for an infection chain to build.

Vaccination rates are dropping in certain areas of the US – and while some parents are adamantly anti-vaccine, fearing autism and other disorders, many parents are just uneasy, the authors wrote.

The authors of the Pediatrics paper reviewed 29 studies on parental decision-making regarding childhood immunization.

While only 1% to 6% of parents spontaneously cited “benefit to others” as a primary reason to vaccinate their children, around 30% to 60%, when asked, agreed that it is an important reason to vaccinate, the authors found.

That suggests that many parents are open to thinking about including public health concerns amongst the various factors they weigh when deciding when and how to vaccinate their children. It’s a tricky balance though, as most studies show that pediatricians should avoid ‘strong-arming’ or guilting parents into putting their kids under the needle.

“Qualitative studies are needed to explore how individual providers and public health initiatives can present the idea of childhood vaccination as a benefit to others, without suggesting that parents consider the welfare of others above that of their own child,” the authors wrote.

In other words: how do you explain the importance of herd immunity to hesitant parents without coming across as a moralizing know-it-all? In delicate situations, the doctor’s words and phrasing can mean all the difference.

Click here

Source:
International Business Times & Pediatrics

Measles study raises questions about timing of vaccination

Monday, September 10th, 2012 (last updated)

A second study from Quebec is calling into question the timing at which children are vaccinated against measles.

The new research supports an earlier study from the same scientists which suggested the measles vaccine might work better if the first dose was given a few months later.

Lead author Dr. Gaston De Serres of Quebec’s provincial public health agency presented the work at an international infectious diseases conference in San Francisco.

Quebec had a large outbreak of measles in 2011, with more than 700 cases reported. Surprisingly, a number of the teenagers infected had received the recommended two doses of vaccine.

A study De Serres did last year showed those who got their first shot at 12 months of age were three times more likely to get infected than those who got their first shot at 15 months of age; his new study put the risk at six times more likely.

A measles expert from the U.S. Centers for Disease Control says public health has to strike an important balance.

Measles can be fatal for babies. So the goal is to give the vaccine as soon as it is effective, Dr. Jane Seward says.

But measles vaccine doesn’t work in young babies if it’s given too early because antibodies they get from their mothers while they are in the womb counteract the vaccine.

Source:
Leader Post & ICAAC

Silk technology preserves vaccines and antibiotics without refrigeration

Monday, September 10th, 2012 (last updated)

Vaccines and other drugs often need to be refrigerated to last, but that can be an obstacle for getting drugs to underdeveloped areas that may need them. Now, researchers at Tufts University discovered that adding a protein made from silkworm cocoons helps maintain the potency of vaccines and other drugs for months and possibly years at temperatures above 110 degrees Fahrenheit.

“Silk protein has a unique structure and chemistry that makes it strong, resistant to moisture, stable at extreme temperatures, and biocompatible, all of which make it very useful for stabilizing antibiotics, vaccines and other drugs. The fact that we can also make silk into microneedles to deliver a vaccine is an enormous added advantage that can potentially provide a lot of useful solutions to stabilization, distribution and delivery,” said David L. Kaplan, who has been studying silk for two decades.

Kaplan and his team found that silk proteins stabilized preserved the efficacy of the measles, mumps and rubella vaccine (MMR), as well as penicillin and tetracycline, at a wide range of temperatures (at least up to 60 degrees C or 140 F) significantly better than other options such as collagen encapsulants, dried powders and solutions.

The key to the silk solution is the structure of the protein, which forms interlocking sheets of crystals that trap medicine molecules in small pockets, protecting them from water, which can start them decomposing. The pockets also held the molecules that maintain their form without unfolding over time, sort of like microscopic bubble wrap.

According to the paper’s first author, Jeney Zhang, who is pursuing a Tufts doctorate in chemical and biological engineering, silk stabilization has “the potential to significantly change the way we store and deliver pharmaceuticals, especially in the developing world.”

It is currently necessary to keep bioactive drugs refrigerated all the way from manufacture to use, wherever that may be on the globe. Health experts estimate that nearly half of all global vaccines are lost due to breakdowns in the “cold chain”. The potential for off-infrastructure healthcare, including in war and disaster zones where electricity is unavailable, is enormous.

Measles is one of the leading killers of children worldwide, and without refrigeration, the MMR vaccine quickly becomes impotent. But after six months of storage in freeze-dried silk films at body temperature and at 113 degrees Fahrenheit, the researchers found that all components of the vaccine retained approximately 85 percent of their initial potency.

Tetracycline and penicillin treated with the silk protein also showed remarkably high activity retained after weeks without refrigeration. Tetracycline without the silk protein boost loses 100 percent of its efficacy after just two weeks of storage without refrigeration. And penicillin loses all active ingredients within 24 hours.

So far, according to co-author Bruce Panilaitis, the researchers haven’t found any pharmaceutical that they have been unable to stabilize. This could be a “universal storage and handling system.”

Source:
International Science Times

Officials issue state-wide whooping cough advisory, calls for vaccinations

Sunday, September 9th, 2012 (last updated)

A significant increase in pertussis, or whooping cough, cases in Texas prompted the Texas Department of State Health Services to issue a state-wide advisory promoting caution and vaccinations.

Calling it a “compelling health issue” state health officials revealed that there have been 1,099 cases of pertussis reported in Texas through August 23rd compared to a total of 961 in 2011.

Six deaths have been reported so far this year. Five of the deaths occurred in infants under two months of age. A sixth death was an unvaccinated child with extensive pre-existing conditions, according to state records.

Pertussis is a contagious bacterial illness usually spread by coughing or sneezing. Cold-like symptoms and a mild cough can progress in a week or more to severe coughing. Young children are at a higher risk because of the threat of apnea, a pause or inability to breathe.

“Infants especially under the age of two may cough to the point of turning blue. They can stop breathing. They can have really potentially deadly consequences from that,” said Helene Sheena, MD with the Department of Pediatrics at Houston’s Kelsey-Seybold Clinic.

The CDC recommends that pregnant women get a pertussis vaccine any time after 20 weeks gestation. Medical professions, including Sheena, recommend “coccooning” as well. They say that anyone who is near a young child, whether a family member, caregiver, or health professional, be vaccinated for pertussis as well.

“Like grandparents, aunts, uncles, the nanny, babysitter, make sure they all have up to date pertussis vaccines,” says Sheena.

The State Health Department says the most notable increases this year have been the counties near Waco, West Texas near Midland and El Paso and south Texas near Corpus Christi and Brownsville–Hidalgo, Bell, McLennan, El Paso, Cameraon, Midland, Whichita, Winkler, Jim Wells, San Patricio, Coryell, Falls and Palo Pinto Counties. Of the 254 counties in Texas, pertussis has been reported in 87 counties.

There has not been a significant increase in the Houston area.  Harris County Public Health reports 24 confirmed cases this year and 12 probable cases of pertussis: numbers locally that are not out of the norm.

For additional information on whooping cough and recommended vaccinations: dhsh.state.tx.us.

Source:
Khou.com (Houston, Texas)

Why are babies dying of old-fashioned whooping cough? It’s not just the fault of parents who don’t vaccinate their kids.

Saturday, September 8th, 2012 (last updated)

In the past few years, diseases that vaccines are expected to prevent have flared across the country. Whooping cough killed 10 babies in California in 2010 and the next year measles sickened 21 people in an outbreak in Minnesota. Now this year, measles has struck 14 in Indiana, causing terror along the way with reports that one infected person had visited Super Bowl village. And whooping cough is on track to infect more people in the United States than it has in 50 years.

You can lay much of the blame for the measles outbreaks on the alarming number of parents who don’t vaccinate their kids. Both the Minnesota and Indiana measles episodes were traced to unimmunized people who had picked the disease up abroad and then spread it to others, many of whom were also unvaccinated (or unsure), according to the Centers for Disease Control and Prevention.

But the story of the whooping-cough outbreaks is more complex, with multiple—and unexpected—sources of risk. To be sure, the illness has struck unimmunized children. But the biggest problem is that the current vaccine wears off faster than researchers anticipated. So substantial numbers of vaccinated children are getting the disease. And since adults are supposed to get a booster, and many haven’t, they’re also vulnerable, even if they got all their shots as kids. The vaccine refusers aren’t helping, but the current epidemic is bigger than they are.

In the bad old days, whooping cough, like measles, infected nearly all children, often causing terrible sickness or even death (listen to the characteristic cough, especially harrowing in babies). It was with the advent of a vaccine for whooping cough, created in the 1940s, that the number of deaths plummeted. Known as DPT (it protects against diphtheria and tetanus as well as pertussis, the scientific name for whooping cough) the 1940s formulation also, however, caused serious side effects—perhaps more so than other childhood vaccines. Many kids developed fevers, some high, and a small number had seizures.

The side effects gave rise to legitimate concern—and also to fear mongering. In 1982, a Washington, D.C., television station broadcast particularly irresponsible “claims of vaccine-induced brain damage, mental retardation and permanent neurological damage,” as Seth Mnookin relates, and debunks, in his superb book, The Panic Virus. The anti-vax movement didn’t need to hear more.* The infamous vaccine skeptic Barbara Loe Fisher became active in the wake of the broadcast, convinced that DPT had caused her son’s developmental problems.

So under intense pressure, researchers set about making a vaccine with fewer side effects. In the late 1990s, the Food and Drug Administration approved a new formulation, called DTaP, for babies and children. Before this, the vaccine used dead whole cells of pertussis to stimulate kids’ immune systems. Now the newer version deployed only a few selected compounds, not cells. The good news is that it hasn’t caused as many side effects. Early clinical trials suggested that this newer, acellular vaccine was also highly effective.

But as Tom Clark, a pertussis expert at the CDC, told me, the studies fell short. They tended not to follow children for a long enough time. Or they defined cases in a way that missed milder infections. As a result, the studies missed a dire fact: The new vaccine doesn’t actually work for as long as the old one.

Now we’re feeling the painful effects. During the 2010 whooping-cough outbreak in California, the largest number of cases, age-wise, were infants under the age of 1. But a notable spike was also seen in kids aged 7 to 10, most of whom had received all of the recommended shots—at 2 months, 4 months, 6 months, 2 to 3 years, and 4 to 6 years of age. These kids were supposed to be safe. What’s more, their risk seemed to increase with age, with the 10-year-olds most likely to get sick. When the CDC picked up that pattern, it “leapt out at us,” Clark says. These were kids who hadn’t received any doses of the old, whole-cell vaccine, which had been phased out completely by 2000. So the uptick strongly suggested that the acellular vaccine’s effects were wearing off year-by-year as the kids got older—long before anyone had anticipated.

Data from this year’s epidemic tell a similar story: Check out this graph showing how the number of whooping-cough cases across the country climbs with age in 7- to 10-year-olds. (Kids receive a booster shot at age 11 to 12, and that helps; still, today’s 13- and 14-year-olds, who may have received only acellular vaccine, are also more likely to get the disease.)

That’s the trouble with the current vaccine. Now here’s how parents who don’t give it to their kids, quite apart from those flaws, are making things worse for all of us. Unimmunized children are simply more likely to get the disease than their vaccinated peers, even with the limitations of the current formulation. And when they do, they are more apt to develop severe symptoms that last longer. This means they’re more likely to pass the disease on to others, including infants, who are at greater risk of dying. Nationally, the anti-vaxers may not be responsible for most of the cases in the spate of recent outbreaks. But that’s mainly because they make up a small fraction of the population.

In the long run, the most important step is a better vaccine. Researchers might add more of the components found in the old one, and try to create long-lasting effectiveness while skirting the old side effects. But that could take a while. The scientific challenges particular to a whooping-cough vaccine are daunting. Unlike measles (or rubella or varicella), pertussis mainly infects the respiratory tract rather than invading the bloodstream. So giving someone a shot intended to produce circulating antibodies, as other vaccines do, may not work as well, because that’s not where the pathogen is mainly found, as Sarah Long, chief of the section of infectious diseases at St. Christopher’s Hospital for Children in Philadelphia, explained to me.

For now, then, the best plan is to double down with the vaccine we have. CDC guidelines give physicians a window for administering whooping-cough shots to children: They can give the first one at six weeks instead of the standard 2 months. They can also offer the 11- to 12-year-old a booster at age 10. This might be a good idea in areas with high levels of disease, says Long. (Protect the 10-year-olds!) Experts might also consider an updated schedule involving more booster shots, though Clark cautions that’s premature. The CDC advises pregnant women to get the vaccine, preferably in the third trimester, so that some antibodies will cross the placenta and continue to circulate in the newborn. Also, since babies are most likely to get pertussis at home, anyone in contact with a newborn, including grandparents and caregivers, should be immunized. (A smart New York law now requires hospitals to recommend the vaccine to new parents.) But with so much whooping cough in the air, no adult should go without the recommended booster (which for adolescents and adults is called Tdap). Only about 10 percent have done so currently, which is a far cry from herd immunity.

Source:
Slate

Infographic: a brief history of the fight to save lives

Friday, September 7th, 2012 (last updated)

Source:
BC DC Ideas