HOW DO MASK HELP ?
Who is at risk?
Pregnant women, especially those in the third trimester, are at an increased risk of serious complications from the H1N1 A influenza virus, says a new report.
With the H1N1 flu outbreak now elevated to pandemic level, the article in CMAJ (Canadian Medical Association Journal) has reported that oseltamivir (Tamiflu) and zanamivir (Relenza) are relatively safe drugs for use in pregnant and breast-feeding women.
For treatment or prevention during the current pandemic, "oseltamivir appears to be the drug of choice because there are more data on its safety in pregnancy," writes Dr Shinya Ito, Head of the Division of Clinical Pharmacology and Toxicology at SickKids.
Zanamivir can be used, although there is less data available about its safety in pregnant women, the expert added.
Neither drug appears to affect the growth and development of the foetus, although ongoing data collection is important. The groups at high risk of flu-related complications from the novel H1N1 influenza are the same as those for seasonal flu – pregnant women, children under 5 years, the elderly and others such as those with chronic lung conditions.
Only small amounts of oseltamivir and zanamivir are excreted into human milk. If an infant is breastfed by the mother on these drugs and needs treatment, the recommended dose of oseltamivir or zanamivir should be given to the infant.
Is there a vaccine? A new research has suggested that targeting children for vaccination could help control the spread of pandemics such as the current swine flu.
The study suggests that targeting kids is the best way of using limited supplies of the vaccine currently being developed.
Ever since the World Health Organization declared a pandemic global H1N1 swine flu, countries are looking at ways to control the spread of the disease.
These measures include the use of antiviral treatments, such as oseltamivir, social distancing (for example, closing schools and stopping public transport) and quarantining infected individuals.
Pharmaceutical companies have also stepped up production of vaccines effective against this particular strain of the virus.
However, if the spread of the disease increases significantly in the autumn, as some scientists predict, it is unlikely that supplies of the new vaccine will be sufficient to vaccinate entire populations.
Dr Thomas House and Professor Matt Keeling from the University of Warwick have used computer modelling to predict the spread of pandemic influenza and to look at ways of controlling it effectively, particularly where supplies of vaccine are not sufficient for universal coverage.
The researchers showed that the disease is likely to spread fastest in densely populated conurbations, suggesting that these should be priority areas for tackling the spread.
However, they showed that vaccinating entire households at random was an inefficient use of resources; instead, vaccinating key individuals offered sufficient protection to others in their household.
Although a simplification of the complex reality of pandemic flu transmission, the researchers believe their model provides a robust argument for vaccinating children. Our models suggest that the larger the household - which in most cases means the more children living at home - the more likely the infection is to spread," said Keeling.
"This doesn`t mean that everyone in the household needs to be vaccinated, but suggests that vaccination programmes for children might help control a potential pandemic," Keeling added.
The researchers argue that targeting children for vaccination would not only help protect those at greatest risk of exposure to the virus, but would also offer protection to unvaccinated adults.
This so-called "herd immunity" effect would mean that significantly less vaccine would be necessary to help control the spread of the virus than if it were offered to everyone.\\
Swiss pharmaceuticals company Novartis AG has said that it has successfully produced a first batch of swine flu vaccine weeks ahead of expectations.
The vaccine was made in cells, rather than grown in eggs as is usually the case with vaccines, the company said.
The announcement comes a day after the World Health Organization declared swine flu, also known as A(H1N1), a pandemic. The move indicates that a global outbreak is under way. WHO says drugmakers will likely have vaccines approved and ready for sale after September.
Novartis said it would use the first batch of vaccine for pre-clinical evaluation and testing. It is also being considered for clinical trials, the company said.
The vaccine was produced at a Novartis plant in Marburg, Germany. Novartis said the facility could potentially produce millions of doses of vaccine a week.
A second plant is being built in Holly Springs, North Carolina, the company said.
Novartis said more than 30 governments have requested vaccine supplies, including the US Department of Health and Human Service, which placed a USD 289 million order in May.
Save yourself: Fight the spread
The World Health Organization issued the following guidelines on Saturday about ways to prevent and fight flu, especially in poor areas where medical facilities may lack staff, beds and drugs:
Social Distancing
-- "Social distancing, respiratory etiquette, hand hygiene, and household ventilation, are at present the most feasible measures available to reduce or delay disease (morbidity) caused by pandemic influenza."
-- This includes keeping at least an arm`s length distance from other people, minimizing public gatherings, and covering coughs and sneezes.
-- Once pandemic flu becomes widespread in a community, however, the WHO said that "interventions to isolate patients and quarantine contacts would probably be ineffective, not a good use of limited health resources, and socially disruptive."
"Routine mask use in public places should be permitted but is not expected to have an impact on disease prevention."
Mild Cases Treated At Home
-- "During a pandemic, very high numbers of patients presenting to the health-care facility will necessitate home treatment," the WHO said.
-- "In the case of mild illness, patients should be provided with supportive care at home by a designated caregiver and only referred to health care facilities if they deteriorate or develop danger signs."
-- Such danger signs may include: weakness or inability to stand, lethargy, unconsciousness, convulsions, very difficult or obstructed breathing or shortness of breath, inability to drink fluids, high fever.
-- Treatment at home should entail rest, fluids, medication for fever, and good nutrition, with patients kept separate from other people except one designated carer who should wash their hands and household surfaces frequently.
-- It is more important in the home that the patient wears a mask than the caregiver. The mask need not be worn all day and only when close contact with the caregiver is anticipated.
-- If enough masks are available, caregivers should also use them to cover their mouth and nose during close contact.
-- Windows should be kept open to allow good ventilation.
In Health Clinics
-- Medical facilities with limited resources and beds should aggressively triage patients and ensure those with respiratory symptoms are kept separately from other patients.
-- Essential medical services should be continued, while elective medical services should be temporarily suspended.
-- Admission criteria may change depending on bed availability, but should be reserved for severe cases most likely to benefit from treatment.
-- "Health facilities should anticipate a very high demand for treatment," the WHO said. "Based on current estimates, agencies should anticipate that up to 10 percent of those who fall ill may require inpatient treatment."
-- The WHO recommends this order of priority for antiviral drugs: a) treatment of sick health-care and other essential staff, b) treatment of sick individuals from the community, c) post-exposure treatment for essential staff at high risk, d) pre-exposure prophylaxis for critical staff with anticipated high-risk exposure.
Interesting Details
The World Health Organization has confirmed at least some of the cases are a never-before-seen strain of influenza A virus, carrying the designation H1N1.
* Although it`s called swine flu, this new strain is not infecting pigs and has never been seen in pigs. The threat is person to person transmission.
* It is genetically different from the fully human H1N1 seasonal influenza virus that has been circulating globally for the past few years. The new flu virus contains DNA typical to avian, swine and human viruses, including elements from European and Asian swine viruses.
* The World Health Organization is concerned but says it is too soon to change the threat level warning for a pandemic-- a global epidemic of a new and dangerous flu.
* When a new strain of flu starts infecting people, and when it acquires the ability to pass from person to person, it can spark a pandemic. The last pandemic was in 1968 and killed about a million people.
* Seven people in the United States have been diagnosed with the new strain. All have recovered, but the U.S. Centers for Disease Control and Prevention expects more cases.
* Flu viruses mutate constantly, which is why the flu vaccine is changed every year, and they can swap DNA in a process called reassortment. Most animals can get flu, but viruses rarely pass from one species to another.
* From December 2005 through February 2009, 12 cases of human infection with swine influenza were confirmed. All but one person had contact with pigs. There was no evidence of human-to-human transmission in those cases.
* Symptoms of swine flu in people are similar to those of seasonal influenza -- sudden onset of fever, coughing, muscle aches and extreme tiredness. Swine flu appears to cause more diarrhea and vomiting than normal flu.
* Seasonal flu kills between 250,000 and 500,000 people globally in an average year.
In 1976 a new strain of swine flu started infecting people and worried U.S. health officials started widespread vaccination. More than 40 million people were vaccinated. But several cases of Guillain-Barre syndrome, a severe and sometime fatal condition that can be linked to some vaccines, caused the U.S. government to stop the program. The incident led to widespread distrust of vaccines in general.
Impact on drug Industry
For hard-pressed drug makers, more used to attacks than applause, the H1N1 flu crisis is a chance to earn political capital by delivering billions of doses of vaccine across the planet.
Recent investment has put companies in far better shape to meet the challenge compared to five years ago, when a single factory closure in northwest England left the world worryingly short of seasonal flu shots.
This time around big flu vaccine makers like Sanofi-Aventis, GlaxoSmithKline and Novartis look set to book extra sales, although constraints on both capacity and pricing will cap the financial upside.
Until now, the main investor focus has been on stockpiling of antiviral drugs to fight the new strain of H1N1 flu, with Roche and Glaxo -- makers of Tamiflu and Relenza respectively -- the two obvious winners.
But that could be about to change as World Health Organization experts meet on May 14 to consider a switch from seasonal to pandemic vaccine production, with companies under intense pressure to show they are good citizens.
Making a vaccine for the new strain, widely known as swine flu, will mean stopping most production of seasonal shots. But because some companies are now well advanced in making next season`s regular vaccine, there is some room to meet both needs.
Companies are not divulging their production schedules but officials at two manufacturers said they were hopeful they would be finished with much of the production needed for the next northern hemisphere flu season by the time of any switch.
Although the H1N1 flu strain seems mild at present, health officials are worried it might return in a more virulent form in the northern hemisphere winter.
Dealing with such an uncertain threat involves a careful balance by health authorities and companies, since making a new vaccine will take four to six months.
The WHO estimates manufacturers have the capacity to make up to 900 million shots annually against seasonal flu, which kills between 250,000 and 500,000 people a year.
Kieny estimates that translates into pandemic capacity of at least 1-2 billion doses, because a simple pandemic vaccine contains only one ingredient, while the seasonal one has three.
Even so, there will not be enough vaccine for the world`s population of more than 6.5 billion.
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