WASHINGTON, Feb 28, (RTRS): People who were morbidly obese and school-aged children were much more likely to become seriously ill or to die from H1N1 swine flu, US experts said on Wednesday.
Preliminary data showed the morbidly obese had four times the rate of hospitalizations and deaths, while the death rate for children was five times higher than usual, experts at the US Centers for Disease Control and Prevention said.
They are working up detailed studies of the pandemic in the United States, the CDC’s Dr Nancy Cox, Dr Anne Schuchat and Dr Lyn Finelli told a meeting of the Advisory Committee on Immunization Practices.
“We estimate that the deaths in children are probably five fold higher, at least, than what is usually seen in seasonal flu,” Schuchat told the meeting.
Deaths among the elderly were about five times less than in a usual flu season, Schuchat added.
Earlier on Wednesday, the World Health Organization said it was too early to say the pandemic had peaked globally, although it has clearly waned in North America and Europe. Cox said the pandemic version of H1N1 had clearly replaced its distant cousin, seasonal H1N1, this year.
WHO and advisers to the US Food and Drug Administration chose this week to replace the seasonal H1N1 component in next season’s flu vaccine with the swine flu strain. But Cox said it is too soon to say H1N1 is just one of several circulating seasonal influenza strains.
“We have yet to see what would happen in the Southern Hemisphere. We would prefer not to jump the gun and say the 2009 H1N1 virus is a seasonal virus,” she said.
Tests
Results from Quest Diagnostics show the number of H1N1 positive tests have dropped 96 percent since the peak in early November.
“The report also finds that 99 percent of all flu tests are H1N1 positive,” Quest wrote in a statement released on Wednesday.
The CDC estimates H1N1 has killed up to 17,000 people in the United States alone.
This compares to about 36,000 people killed every year by seasonal flu, but Finelli noted that it takes months to gather data on deaths. Flu weakens people who then can die of heart attacks or strokes and Finelli said once that data is included, deaths this season from swine flu may be more than the normal 36,000. The CDC and WHO both say people who have not been vaccinated should still get an H1N1 vaccine.
The CDC’s Dr James Singleton told the meeting that by Feb 13, 97 million H1N1 vaccine doses had been given to 86 million people in the United States, or 78 percent of doses shipped. Singleton said a monthly telephone survey of 6,000 US households suggested that a third of children, many of whom need two doses, and about 20 percent of adults had received swine flu vaccines.
People will need seasonal flu vaccines, too, Cox noted. Globally, H1N1 or untypeable viruses likely to be H1N1 made up about 90 percent of viruses taken from patients but H3N2 flu viruses accounted for nearly 6 percent and are on the rise in China. And a new variant of H3N2 has emerged that is different from the one covered in the current season’s vaccine.
Vaccine makers must reformulate the three-ingredient seasonal flu vaccine every year because of such changes.
The United States has contracts with five influenza vaccine makers - Novartis, AstraZeneca unit MedImmune, Sanofi Aventis, GlaxoSmithKline and Australian vaccine maker CSL. The WHO has been accused of inflating the threat posed by swine flu, but many experts commend the UN health agency for caution and warn that what is a minor peril today may still rebound in more vicious form.
After mulling the state of the emergency it declared last June, the World Health Organisation (WHO) decided on Wednesday it was still too early to say the global pandemic had peaked.
That decree may chafe critics who have blasted the WHO for classifying as a pandemic - the highest level of threat - an outbreak that proved even less lethal than regular flu.
So far, the new H1N1 strain has killed around 16,000 people, and infected tens and possibly hundreds of millions, according to the WHO.
By comparison, ordinary “seasonal” influenza claims about half a million lives each year, while the 20th century’s three flu pandemics killed between between one or two million people each in 1957 and 1968, and maybe 50 million in 1918-1919.
Criticism has also focused on the billions spent on vaccine, cranked out at top speed by major pharmaceutical manufactuers, to inoculate entire populations.
Vaccination
Many orders have since been cancelled and vaccination rates have been relatively low. In a world population of 6.7 billion, around 200 million people worldwide have gotten the H1N1 jab, according to UN estimates.
“We have to draw lessons from the crisis so that we don’t repeat our mistakes,” said Marc Gentilini, former head of the French Red Cross and an expert on infectious disease.
Citing the French case, he told AFP that the attempt to administer a blanket vaccination was “logistically too cumbersome, grotesque and unrealistic.”
But most experts argue that the UN body took the right course of action.
“The WHO acted appropriately at the time and with the information they had available. The rate of spread of the virus was phenomenal,” said Nigel Dimmock, a virologist and emeritus professor at Warwick University in Britain.
Christophe Fraser, an epidemiologist at Imperial College London who participated in several key swine flu studies, said the process “was entirely appropriate.”
“I don’t think we had the kind of information that would have told us this was a very mild virus and was going to stay a very mild virus,” he said.
Mark Miller, a top epidemiologist at the US National Institutes of Health, agreed that the “uncertainty of a potential catastrophic public health emergency” left little choice but to develop a new vaccine and quickly scale up production.
Several specialists cautioned that it is still early days, and a re-emergent H1N1 strain could be extremely nasty.
“Everyone thinks this is a post-mortem, but unfortunately this virus is not dead yet. It is on a trajectory, and we don’t know where it is going to end up,” said John Oxford, a virologist and professor at the Queen Mary’s School of Medicine and Dentistry.
The new strain is a “Darwinian super virus” that has quickly pushed other strains to the sideline, as as happened in previous pandemics, Oxford said.
He also observed that the new bug was still mutating. “In the past, more often than not, the first wave has been overshadowed by the second and third waves,” he said by phone.
Lone Simonsen, an epidemiologist at George Washington University, points out that about 70 percent of the fatalities from the 1968 pandemic occurred in the second year.
She and others also cautioned that older persons less affected by the new strain - perhaps due to a partial immunity lingering from exposure to the pre-1957 flu, also an H1N1 variant - might become more vulnerable.
While they defend the WHO, experts agree that some changes are needed in the pandemic alert and management system.
“Perhaps they could improve public perception in the future by having pandemic scientific advisors who have no conflict of interest” with pharmaceutical companies, said Simonsen.
Several called for adding some measure of virulence to the threshold definition of pandemic, though they point out that it is difficult to assess lethality in the early stages of an outbreak.
Others say that far more research is needed into the link between animal and human diseases.
“There’s a huge gap between human and veterinary virology,” said Oxford, noting that the swine flu went unnoticed for more than a decade while still in pigs.
“This is a huge problem for us,” said Fraser. “The surveillance of influenza in pigs is terrible - its a scandal.”