Obesity a risk factor in H1N1?

ATLANTA – Some swine flu cases in America are raising questions about obesity’s role in why some people with infections become seriously ill.

A high proportion of those who have gotten severely ill from swine flu have been obese or extremely obese, but health officials have said that might be due to the fact that heavy people tend to have asthma and other conditions that make them more susceptible.

Obesity alone has never been seen as a risk factor for seasonal flu.

But in a report released Friday, health officials detailed the cases of 10 Michigan patients who were very sick from swine flu in late May and early June and ended up at a specialized hospital in Ann Arbor. Three of them died.

Nine of the 10 were either obese or extremely obese. Only three of the 10 had other health problems. Two of the three who died had no other health conditions.

This hardly settles the question of whether obesity is its own risk factor for swine flu. It’s possible the patients had undiagnosed heart problems or other unidentified conditions.

Still the finding was striking, investigators acknowledged.

Also remarkable were that five of the patients developed blood clots in their lungs, and six had kidney failure. Those complications have been seen in some swine flu patients before, but not usually in such a high proportion.

“Clinicians need to be aware that severe complications can occur in patients with the novel H1N1 virus, particularly in extremely obese patients,” said Dr. Tim Uyeki, a flu expert at the Centers for Disease Control and Prevention.

Uyeki was a co-author of the report, released by a CDC publication, Morbidity and Mortality Weekly Report.

Also on Friday, the CDC said the number of US swine flu cases has surpassed 37,000 and deaths have risen to 211.

The numbers rose from the 170 deaths and nearly 34,000 confirmed and suspected swine flu cases reported last week.

Those are lab-confirmed and probable infections. CDC officials believe those cases – which sought treatment and underwent testing – are just the tip of the iceberg. They estimate more than one million Americans have been infected with the virus so far, though many probably had only a mild illness.

Swine flu is the predominant flu type circulating currently, with nine states reporting widespread cases, down from 10 a week ago.

The pandemic was first identified in California in April. Since then a total of more than 94,000 cases have been reported in more than 100 countries, according to the World Health Organization.

UK records first H1N1 death in healthy patient

British health authorities said on Friday they had recorded the first death from H1N1 flu in an otherwise healthy patient.

The patient from Essex, eastern England, is the 15th to die in Britain from the virus, but unlike all the others had no underlying health conditions.

“This death underlines that, although the virus is proving generally mild in most people, it is more severe in some cases,” said Britain’s Chief Medical Officer Liam Donaldson.

“As with all flu-like viruses, some people are at higher risk than others. Unfortunately, people who are otherwise healthy could also become seriously ill or, sadly, die,” Donaldson said.

The unnamed patient died on Friday at Basildon and Thurrock University Hospitals Trust in Essex.

The Department of Health said on Thursday the rapid spread of infection in London and the West Midlands was close to epidemic level.

It said Britain had 9,718 laboratory-confirmed cases, the third most in the world behind the United States and Mexico, although the actual number of cases was likely to be higher.

The other 14 patients who have died all had underlying health issues and it is not clear in how many cases the patients had died as a direct result of the virus, known as swine flu.

The World Health Organization declared on June 11 the outbreak of the virus was a pandemic and more than 94,500 cases have been reported worldwide.

Britain’s Health Minister Andy Burnham said last week the government was projecting more than 100,000 new cases a day of the flu by the end of August.

While most people who have caught the infection have suffered mild symptoms, in a small minority it has proven more severe.

Flu vaccine line

The WHO plans to release guidance next week on the need for a vaccine against the new H1N1 swine flu virus.

Companies are already working to make one.

Few experts doubt there will be an H1N1 vaccination campaign but questions remain about how much companies should be prepared to make, whether to try to stretch the supply using ingredients called adjuvants and who should get the vaccine.

Here are some potential scenarios:

• Full speed ahead

WHO could advise companies to switch to full-speed production of an H1N1 swine flu vaccine for the northern hemisphere’s autumn, with the goal of getting a maximum 4.9 billion doses ready. More doses would be needed if clinical trials show that people will need two shots a few weeks apart to get the best protection.

Even more doses would be needed if children aged two to nine turn out to need three doses. Currently, unvaccinated children under nine need two influenza vaccinations the first year to get full protection from seasonal flu.

It is possible WHO will recommend that all age groups be immunized against the new H1N1 virus. Usually, countries issue guidelines for specific age groups, depending on who is worst hit and balanced against vaccine availability.

The elderly and the very young are usually at the front of the line for influenza vaccines because they are most likely to die or develop serious complications.

Between 250,000 and 500,000 people die every year from seasonal flu, but this new virus targets older children, young adults and people with conditions such as asthma, pregnancy and heart disease.

• Limited production

WHO may advise companies to proceed with limited and cautious production of a vaccine, keeping in reserve the possibility of a stepped-up seasonal flu vaccination campaign.

Vaccine makers such as Sanofi-Aventis, Novartis, Baxter, Schering-Plough subsidiary Nobilon, GlaxoSmithKline and Solvay and AstraZeneca’s MedImmune subsidiary have finished making seasonal flu vaccines for this year.

The seasonal formula is a cocktail of three different strains – the seasonal H1N1 strain, a very distant cousin of the pandemic strain, an H3N2 virus and an influenza B virus.

H1N1 is spreading in places where seasonal flu is circulating and scientists say it has the potential to mix in a flu patient’s body and emerge as a new, unpredictable strain.

Controlling seasonal flu may be at least as important as controlling H1N1.

Limited production may be recommended if it appears the virus has started to change, making a vaccine less protective. Infectious disease experts say there is little sign of this so far.

WHO may also recommend limited production while clinical trials – tests in people – get underway. US health officials said this week those trials will get started in August and will give more information about whether the vaccine is safe and what kind of immunity it produces.

Using an adjuvant to boost immune response to a vaccine is possible as well. Such a vaccine would not be licensed but US regulatory authorities may allow it under emergency use provisions. Adjuvants can be mixed with vaccine after it is made so their availability would not affect production.

What is known

Most people have limited immunity to the new H1N1 swine flu virus. It is a mixture of two pig viruses, one of which is itself a mixture of pig, human and bird viruses.

There is some suggestion that people over the age of 50 may have some immunity to the virus, perhaps because it is similar to H1N1 strains that circulated before the 1957 pandemic that killed two million people globally. In that pandemic, H1N1 strains were replaced within months by a new strain called H2N2, and H1N1 did not reappear again until the 1970s.

Health officials already agree that vaccination campaigns should focus on school-age children, as they are not only among those most at risk of infection but schools serve as breeding grounds where viruses of all types spread.

In addition, people with underlying conditions, including pregnant women, are among groups that would be at the head of the line, as well as healthcare workers who must stay healthy to care for the sick and administer vaccines. – AP