Vaccine developed to protect against norovirus

reposted from: http://www.guardian.co.uk/science/2012/feb/17/vaccine-norovirus-winter-vomiting-bug
by Ian Sample in Vancouver, The Guardian, Friday 17 February 2012 18.00 GMT

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Vaccine developed to protect against norovirus or 'winter vomiting bug' 

A vaccine for norovirus, which is highly infectious and is difficult to kill by cleaning, could be available within five years.

People infected with norovirus (above) can remain infectious for more than three weeks. Photograph: CDC/Phanie/Rex Features 

A vaccine against the highly infectious winter vomiting bug that strikes thousands of people in Britain each year is close to being tested in humans.

Doctors have approached government funders to begin human trials after laboratory tests showed the vaccine could prevent people from succumbing to the infection.

Researchers said the technical issues in formulating the vaccine appeared to be solved, and that regulators now had to assess the treatment's suitability for full-scale clinical trials.

The stomach bug, caused by seasonal norovirus, spreads rapidly between people and is difficult to kill off by cleaning. It has ruined countless holiday cruises, closed hundreds of hospital wards and torn through prisons.

In recent weeks, three US cruise ships have been forced to return early to their ports for deep cleaning after outbreaks of norovirus saw hundreds of passengers and crew struck down with diarrhoea and vomiting. Cruise ships are required to report norovirus outbreaks to the US Centres for Disease Control and Prevention when 3% or more of those onboard go down with the bug.

"When it hits in a situation like a cruise ship, it spreads like wildfire," said Charles Arntzen, co-director of the Centre for Infectious Diseases and Vaccinology at Arizona State University.

Laboratories in England and Wales have confirmed more than 1,100 cases of norovirus in the first four weeks of 2012, according to figures from the Health Protection Agency. So far in this winter season there have been 755 outbreaks in English and Welsh hospitals, leading to 520 ward closures or restrictions on admissions.

Though the illness is generally mild and clears up in two to three days, people can remain infectious for more than three weeks. Most people who are fit and healthy make a full recovery.

"You can have diarrhoea and wash your hands thoroughly afterwards, but if you leave as few as 10 viruses on a door knob, and someone else picks it up, they can get the disease and spread it," Arntzen said. Since the 1980s, a second, more virulent strain of norovirus has emerged and now accounts for around 85% of outbreaks.

To develop the vaccine, scientists working with Arntzen took a gene from norovirus that codes for its protective protein coat and added it to a common tobacco virus. When the virus infected tobacco plants and multiplied inside their cells, it produced thousands of copies of the norovirus protein, which coalesced into virus-like particles. The particles are harmless, but can be used in a vaccine to trigger an immune attack on the virus.

Arntzen's group has teamed up with a group in Kentucky that grows tobacco plants on an industrial scale to manufacture the vaccine. From 1kg of tobacco plant, the researchers can make 10,000 doses of vaccine.

Lab tests of the vaccine showed it was most effective when given as a nasal spray, combined with a dried aloe extract, which made the vaccine stick to mucous membranes in the nose. Vaccine that contained aloe stayed in the nose for around three hours, which is long enough to prime immune defences in other mucous membranes around the body including the gut, where the norovirus strikes.

The results were presented at the annual meeting of the American Association for the Advancement of Science in Vancouver.

The final version of the vaccine is likely to carry virus-like particles from both major strains of norovirus, and possibly some common sub-strains, to ensure it provides broad protection against the bug. A single shot of nasal spray could be effective for six months to two years, Arntzen said.

The vaccine, which could be available in four to five years, may prove popular in children's day care centres and among cruise ship workers, hospital staff, carers in old people's homes, and the military, all of which face regular outbreaks of norovirus.

Is Whooping Cough Vaccine Refusal Worth The Risk?

reposted from: http://www.npr.org/templates/story/story.php?storyId=104523437

Is Vaccine Refusal Worth The Risk?

by Patti Neighmond

Over the past 10 years, a highly contagious and sometimes fatal bacterial disease once thought to have been eradicated from the U.S. has re-emerged, threatening the youngest and weakest. Pertussis is a bacterial infection of the lungs and spreads from person to person through moisture droplets in the air, probably from coughs or sneezes. A person with pertussis develops a severe cough that usually lasts four to six weeks or longer.

Health officials cite an increase in the incidence of pertussis, particularly among infants and teenagers. In 1976, there were just over 1,000 reported cases of pertussis in the United States; by 2004, it had climbed to nearly 26,000 cases; and between 2000 and 2005,

there were 140 deaths resulting from pertussis in the U.S.

At the same time, studies and anecdotal reports from doctors nationwide report an increase in the number of parents refusing to vaccinate their children against childhood diseases.

Much of this refusal has to do with perceived vaccine safety issues, such as purported associations between vaccines and autism, attention deficit disorder, seizures and epilepsy. None of these concerns have been upheld in research. In fact, all scientific studies show vaccines to be highly effective and safe, with only rare, moderate, adverse side effects.

Results of a new study, published in the June issue of the journal Pediatrics, show that the biggest risk among children who are not vaccinated is the disease itself, as well as the risk of spreading it to more vulnerable populations who, for age or medical reasons, are unable to get vaccinated.

In pertussis, coughing occurs in sudden uncontrollable bursts, where one cough follows the next without a break for breath. Many people make a high-pitched whooping sound when breathing in after a coughing episode, hence the nickname "whooping cough." Coughing can be so severe, patients can vomit or break ribs.

A patient's face or lips may look blue from lack of oxygen, and the cough is often worse at night. Between coughing spells, the person seems well, but the illness is exhausting over time. Coughing episodes gradually become less frequent, but may continue for several weeks or even months until the lungs heal.

People of any age can get pertussis. Older children and adults usually have a less severe illness, but they can still spread the disease to infants and young children.

Pertussis in infants is often severe, and infants are more likely than older children or adults to develop complications, the most common of which is bacterial pneumonia. Rare complications include seizures, inflammation of the brain and death.

In the study published in Pediatrics, researchers from Kaiser Permanente Colorado's Institute for Health Research used electronic health records to look for immunization refusal and possible pertussis infections.

Specifically, researchers examined the medical records of children 2 months old to 18 years old who were members of Kaiser Permanente Colorado between 1996 and 2007. First, investigators confirmed which children had pertussis infections. Next, they verified whether parents had refused some or all vaccines for their children.

Researchers found that children of parents who refused the vaccine were 23 times more likely to get whooping cough compared to fully immunized children. "A 23-fold increase is huge," says Jason Glanz, a senior scientist at Kaiser Permanente's Institute for Health Research who headed the study.

Glanz says the findings should help "dispel one of the commonly held beliefs among vaccine-refusing parents: that their children are not at risk for vaccine preventable diseases."

And from a larger perspective, Glanz says the findings also show "that the decision to refuse immunizations could have important ramifications for the health of the entire community. Based on our analysis, we found that 1 in 10 additional whooping cough infections could have been prevented by immunization."

Glanz, a father of young children himself, says vaccines "can pose confusing and difficult choices." The purpose of the study was to give parents more information to weigh the benefits and risks, he says, as well as to provide pediatricians with more information to help them participate in the discussion.

For the physician, "it's an uphill battle", says Glanz, since most pediatricians today have so little time to spend with parents, and it's difficult to discuss the risks and benefits of vaccines with parents who have lots of questions and want thorough answers.

On top of that, physicians are battling a lot of misinformation, says Glanz. The Internet, for example, is easily accessible and often misleading, with numerous scary descriptions of devastating diseases purported to result from vaccines.

All of this adds up to a critical need for the public health community to develop effective "risk communications messages" that "resonate with parents" in order to help them make truly informed decisions about vaccinating children, he says.

Doctors need simple targeted information about the actual risks of having the vaccine and the risks of not having it. They need to know, says Glanz, that their child could actually become infected by the pertussis bacteria.

In addition, Glanz says, it should be very clear among parents "that by keeping immunization rates high, we protect everyone, including the most vulnerable populations."

There are a number of individuals for whom vaccination against pertussis is not possible. The vaccination is not effective for babies younger than 2 months old because their immune system is not yet fully developed and capable of responding.

Then, there are older children who suffer other medical conditions that compromise their immune system and also make pertussis vaccination ineffective. When parents protect their own child, says Glanz, they "also protect this most vulnerable population."

Dr. Randy Bergen, a pediatrician who specializes in infectious diseases, says some of the most compelling data he's seen comes from California, which reports that between 2001 and 2006, there were 24 deaths from pertussis. All of those deaths occurred in infants younger than 2 months of age.

The only way to protect these infants, says Bergen, is by "cocooning, where we immunize and protect those around the infants. And that's where the real concern is, especially when it comes to pertussis; that by not vaccinating school-age children, adolescents and young adults, we're leaving these infants unprotected."

Bergen suggests that, ironically, vaccines are almost victims of their own success. "Unfortunately, vaccines have been so successful in reducing diseases that not only are parents unaware of the potential severity of these diseases, but many pediatricians have rarely seen them and don't know the potential severity of these diseases either."

The recent number of infant deaths from pertussis should certainly serve as a wake-up call. As for vaccine safety, Bergen says there have been a large number of studies that have looked at safety over the past 10 years: "None of these studies have proved any association between a vaccine, a preservative in a vaccine or a combination of vaccines, and significant adverse problems." Vaccines in this country are safe, he adds; they "prevent diseases that can maim and kill."

The childhood vaccine known as DTaP protects against diptheria, pertussis and tetanus. It is given in a series to children at 2 months, 4 months, 6 months and 15-18 months of age; a booster is given before kindergarten. The DTaP vaccine, like other routine childhood immunizations, has been shown to be more than 98 percent effective.

Recent outbreaks of pertussis among teenagers have led to investigations into the long-term efficacy of the vaccine. They conclude that potency wanes as children get older. Today, federal health officials recommend children get another booster shot at around 11-13 years of age.