US Areas Hit Hard by Swine Flu in Spring See Little Now--Herd Immunity?

Areas Hit Hard by Swine Flu in Spring See Little Now
By ANEMONA HARTOCOLLIS and DONALD G. McNEIL Jr.

New York Times, Published: October 8, 2009

While concern over the spread of the H1N1 virus sweeps the country, epidemiologists in New York and a few other cities that were awash in swine flu last spring are detecting very little evidence of a resurgence.

Although flu season will not peak until the weather gets cold, in New York, which was the nation’s hardest-hit city, officials say that flu activity is no higher than it normally is at this time of year and that school attendance is normal.

Last week, Dr. Anne Schuchat, the director of immunization at the federal Centers for Disease Control and Prevention, said, “Most states do have quite a lot of disease right now, and that’s unusual for this time of year.”
But public health officials say there appears to be a pattern of areas that had big outbreaks in the spring, like New York, Boston and Philadelphia, seeing less swine flu now.

New York City health officials now believe that while only 10 percent to 20 percent of New Yorkers were reported ill with flu last spring, as many as 20 percent to 40 percent may have been exposed to the disease and developed immunity that has prevented it from spreading.

Although it is too early to be sure, they said, the high level of immunity may mean that the second wave of swine flu infection ends up being far less extensive than expected.

The immunity theory has gained enough credence that Dr. Thomas A. Farley, New York City’s health commissioner, put it forward at a conference on the national preparations for H1N1 last Friday in New York, led by Kathleen Sebelius, the health and human services secretary, and Dr. Thomas R. Frieden, director of the disease control centers.

“We’re not seeing illness in the city right now,” Dr. Farley said at one session. “We’re seeing essentially no disease transmitted in the city. We had 750,000 to one million sick people last spring. We were the hardest-hit city then. So we have a lot of immune people right now.”

Officials say the conflicting data show the delicate balance public health officials are walking with swine flu. So far it has turned out to be less deadly than it seemed when a pattern of deaths was reported in Mexico last spring.

At the same time, officials fear that it could take a turn for the worse, and they want to maintain a high level of alertness without crying wolf too many times.

Dr. Martin S. Cetron, a flu expert at the disease control agency and the co-author of a 2007 study of how the 1918 flu hit 43 American cities, called the idea that flu is not big now because it was big in the spring “an interesting hypothesis, with biological plausibility,” but said that only the rest of the winter would tell.

“To say, Oh, all of us in New York are immune, we won’t have any more disease and we don’t need to take vaccine, is a dangerous conclusion to draw,” Dr. Cetron said.

New York City public health officials are in fact conducting an extensive immunization campaign, and they agree that it is far too early to draw any final conclusions.

“It’s like Sherlock Holmes looking at the evidence and saying, ‘Hmmm, that’s a plausible solution,’ ” Dr. Don Weiss, an epidemiologist with New York City’s health department, said Wednesday. “This sort of fits with what we’re seeing, but there could be other explanations.”

Still, Dr. Weiss added, “The theory that everybody’s talking about is that maybe because New York had such a bad outbreak in the spring, it won’t be so bad in the fall.”
The amount of immunity in a population, called the herd immunity, “will tell you whether or not you will have an outbreak,” Dr. Weiss said.

For highly infectious diseases, like measles, it is generally accepted that 90 percent to 95 percent of the population has to be immunized to prevent an outbreak, he said.

For flu, a virus that is constantly changing year to year, it is less clear what the herd immunity has to be to prevent a further outbreak, but it may be as little as half, and New York may be very close to that, Dr. Weiss said.

Since September, only about 150 to 250 people a day have been going to New York City emergency rooms complaining of flu-like symptoms, officials said. The presumption in New York and elsewhere is that most flu cases this time of year are swine flu, because it is still early in the year for so-called garden-variety flu.

Attendance in the New York City’s public school system, with just over a million students, was 91 percent Wednesday. Last spring, when the virus was rampant, nearly 60 schools were closed and about 18 percent of students were absent.

In Boston, where an estimated 11 percent of adolescents got swine flu in the spring, public schools and college health services have reported very little flu activity this fall, Dr. Anita Barry, director of the infectious disease bureau of the Boston Public Health Commission, said Wednesday.

But Dr. Barry said she was reluctant to draw any conclusions so early in the season, without taking blood samples to test for immunity.

Seattle, Connecticut and Utah also had lots of swine flu in the spring, but appear to have less now, said Donald R. Olson, research director for the International Society for Disease Surveillance.

Some states, including Georgia, Indiana and North Carolina, had “false waves” of swine flu in the spring, Mr. Olson said, which seemed to have been caused by the “worried well” flocking to hospitals.
“Of the places that had ‘real waves’ last spring,” he said, “none have really taken off.”

Georgia in particular took off when schools reopened in August. In the last week of September, there were 81 hospitalizations and eight deaths from H1N1 in the state, according to the Georgia Department of Community Health, compared with 44 hospitalizations and one death in the three-months from late April through late July.

As of Monday, seven pregnant women were on respirators in Arkansas hospitals, officials said.
“We’re hearing from doctors and clinics across the state that they’re swamped,” said Ann Wright, a spokeswoman for the Arkansas Department of Health.

Since August, about half the children seen in the emergency room at Arkansas Children’s Hospital in Little Rock have complained of flu, about double the usual number for this time of year, said Craig H. Gilliam, the hospital’s director of infection control.

Mr. Gilliam said the hospital had a record number of emergency room visits on Sept. 15, which he attributed to the flu.

Jennifer Medina contributed reporting from New York, Robbie Brown from Georgia and Steve Barnes from Arkansas.

Certain US states could run out of hospital beds for H1N1 Flu second wave

Certain US states could run out of hospital beds for H1N1 Flu second wave

CHICAGO, Oct 2 — Fifteen states could run out of hospital beds and 12 more could fill 75 per cent of their beds with H1N1 sufferers if 35 per cent of Americans catch the virus in coming weeks, a report released yesterday said.

The study, based on estimates from a computer model developed by the US Centres for Disease Control and Prevention, shows the strain hospitals and health departments could face as a second wave of H1N1 surges.

“Our point in doing this is not to cry Chicken Little but really to point out the potential even a mild pandemic can have and how readily that can overwhelm the healthcare delivery system,” Jeffrey Levi, director of Trust for America’s Health, which sponsored the report, said in a telephone briefing.
According to the report, the number of people hospitalised could range from 168,025 in California to 2,485 in Wyoming, and many states may face shortages of beds.

Some may need to cut back on hospitalisations for elective procedures.

“States around the country will also have to figure out how to manage the influx of people in doctors’ offices and ambulatory care settings, in addition to the surge in hospitalisations,” Levi said.

He said state and local health departments are scrambling to set up distribution systems for the H1N1 vaccine as it becomes available this month, but challenges remained.

“These systems are untested, and glitches are sure to arise along the way,” Levi said.

Local health authorities are especially worried about reaching young people, who traditionally are not vaccinated for flu, and minorities, who were harder hit by the swine flu in the spring.

While the federal government will pay for the vaccine itself, Levi said, it was not yet clear how the actual cost of giving the shot will be financed.

Although many public and private insurance plans have said they will cover it, others have not yet agreed.

“This could become a huge burden for state and local health departments, or become a dangerous disincentive for people to get a vaccine,” he said.

The 35 per cent attack rate used in the report is based on the 1968 flu pandemic, which was considered mild. It assumes an outbreak would last around eight weeks.

Levi said the number was consistent with World Health Organisation statements predicting that up to a third of the world’s population will become sick with the new H1N1 virus that was declared a pandemic in June.

The President’s Council of Advisors on Science and Technology said in August that 1.8 million Americans may need to be hospitalised and around 30,000 could die, assuming a 30 per cent infection rate. — Reuters

WHO: H1N1 widespread, but so far not more lethal than earlier...

WHO: H1N1 has killed 2,837, but not more serious

World Health Organisation (WHO) said (September 4, 2009) that thus far the pandemic H1N1 flu virus continues to spread extensively in many parts of the world but has not become more serious.

The WHO said it had counted 2,837 deaths worldwide but noted that not every case was being counted any more.

WHO is closely monitoring the strain, commonly known as swine flu, and has not detected any mutation which might signal that it has become more deadly.

WHO spokesman Gregory Hartl told a news briefing, “We are continuing to see increased number of deaths because we are seeing many, many more cases.” About 250,000 cases have been laboratory-confirmed worldwide, but this is far fewer than the true number according to the WHO which has stopped requiring its 193 member states to report individual cases.

Its previous update of Aug. 28 showed at least 2,185 deaths, meaning an additional 652 deaths were reported in the past week. The virus could eventually infect 2 billion people, or a third of the world’s population, according to WHO estimates.

Every year, seasonal influenza kills between 250,000 and 500,000 people globally, it says. But H1N1 is causing a year-round flu season and may infect more people than a usual seasonal virus, potentially adding up to more deaths.

“In the best case scenario we have today, we will still have a moderate virus that is projected to cause several million deaths,” Dr. Tammam Aloudat, senior health officer at the International Federation of Red Cross and Red Crescent Societies, told a separate news briefing.

“Which means that even in the best case scenario, we do have an emergency on our hands, an emergency of a scale different from what we have seen before in the modern era,” he said.

PREDOMINANT VIRUS
Tropical regions of many countries in South and Southeast Asia are reporting “increasing or sustained high levels of respiratory disease”, although Thailand has reported a declining trend, according to the WHO’s latest weekly update.

In Latin America, countries including Ecuador, Venezuela, Peru and Brazil are reporting more respiratory disease, while outbreaks seem to have peaked in Chile and Argentina, it said.

Japan is seeing an early start to its regular flu season. In Canada and the United States, influenza activity remains “low overall”, despite increases in the southeastern US region.

Drugmakers are racing to develop vaccines amid experts’ warnings that a “second wave” of the virus is approaching as weather cools in the northern hemisphere and the traditional flu season starts.

Yesterday, Novartis AG said a single dose of its vaccine might protect against the virus, raising hopes that potentially tight supplies could go further when mass immunisation starts this month.

Hartl has called the preliminary results “encouraging”, noting any vaccine that can be administered in one dose would substantially increase the number of overall doses available. — Reuters

Singapore braces for second H1N1 wave

Singapore hospitals brace for new H1N1 wave

A recent Singapore press statement (The Straits Time, September 4, 2009) noted that hospitals in the tiny island republic, have been asked to brace for a possible second wave of Influenza A (H1N1), even as the number of cases decline recently.

So although some among our citizens and doctors have felt that this A(H1N1) flu is just another flu, 'hyped up' to be worse that it really is, such sentiments should be considered as outside conventional wisdom.

While we welcome contrarian viewpoints, we should still be prudent when it comes to public health initiatves and direction.


Infectious disease experts in Sinagpore estimated that the first wave had infected about 700,000 people there, which means that some four-fifths of the population have still not been exposed to the virus.

As of Aug 31, 1,181 people with H1N1 had been hospitalised, with 77 needing intensive care. To date, 17 have died: four had no pre-existing conditions.

Associate Professor Paul Ananth Tambyah, head of the National University Hospital’s infectious diseases division, said the numbers were in line with those from other countries and validated Singapore’s approach to have pandemic-preparedness clinics look after the vast majority of patients with flu.

The WHO predicts that two billion people will likely be infected worldwide by this new virus, with a “second wave” expected during winter in the northern hemisphere, the traditional flu season. But as the virus has not changed much so far, the outbreak is likely to be mild and not drawn out, said doctors.

The Singapore health ministry is taking no chances, and will have two million courses of the anti-viral drug Tamiflu by the end of this year, almost double the original stockpile. Another 200,000 courses of Relenza will be added to the current 550,000 in the national stockpile. Singapore has a contract with Australian drug maker CSL for a pandemic vaccine, enough for the population.

Europe braces for possible autumn surge in H1N1

Health experts warn Europe of feared swine flu surge

Fri Aug 28, 2009 8:57am EDT

By Kate Kelland

LONDON (Reuters) - Health authorities across Europe are bracing for a third of their populations to become infected with the new swine flu virus this autumn, but do not plan to close schools or take other drastic measures to stop it.

Instead, they plan to educate people about hygiene, get vaccines out as soon as possible, and hope the H1N1 pandemic does not become deadlier than it has been.

Some 200,000 doses of vaccine have just been delivered in Britain by drug firm Baxter International and many other European countries are expecting it to arrive from October onwards. That should be just in time to prevent mass illness.

Companies making H1N1 vaccines include AstraZeneca's MedImmune unit, GlaxoSmithKline, Novartis AG, CSL and Sanofi Aventis.

Epidemiologist Giovanni Rezza, head of Infectious Diseases at Italy's Higher Health Institute said Italy, like Spain, France and others, aimed to vaccinate 30 to 40 percent of its population, a level he said was "practical and sensible."

"You have to consider that the indirect impact would be enough to stop the virus from spreading quickly among the population," he said.

France, where schools restart on September 2, unveiled its autumn swine flu plan this week, launching a month-long public information program of radio, television and Internet adverts urging people to keep clean and vigilant, and suggesting they should sneeze into their sleeves if they have no handkerchief to hand.

Slovenia and Austria have similar plans.

"All the teachers have been briefed ... and every household will get a leaflet with instructions on personal hygiene," said Slovenia's Health Ministry spokeswoman Irma Glaner.

In Spain, the socialist government plans to prioritize health workers and teachers when it gets a vaccine but has rejected opposition calls to delay the start of the new school term and a teachers union request for pregnant teachers to be allowed not to return until a flu vaccine arrives.

EUROPE AWAITS "WAVE OF TRANSMISSION"

Large-scale school closures, as in Britain when swine flu first began to take hold in April and May, are not on the agenda for any European government; a decision that health experts generally condone.

Although the virus causes mild symptoms in many people, some develop severe complications and deaths have occurred among pregnant women, young children, people with underlying health problems like obesity and diabetes and even healthy adults.

"It remains the case that this disease is not a killer, but it can kill," England's chief medical official Liam Donaldson said on Thursday.

The H1N1 strain has now spread to 177 countries, causing at least 1,799 deaths, the World Health Organization said.

Angus Nicoll, flu coordinator at the European Center for Disease Prevention and Control (ECDC) in Stockholm, pointed to southern hemisphere countries like Australia where the ECDC's latest data show 147 people have died and 422 are in hospital with the virus, more than a fifth of them in intensive care.

"They have gone through an intense wave of transmission," Nicoll said. "The numbers of people who have been infected in Europe are pretty moderate, but it seems inevitable to us that Europe should be preparing for an autumn and winter of transmission.

"There are countries like Spain, Germany, the UK and others, where we have got low-level transmission now. And it won't take a lot to tip them over into accelerated transmission."

The new school year, which begins in countries across Europe in the next few weeks, could be the trigger.

Young children can spread any virus from schools and daycare centres, and health and education authorities plan to push hygiene and information about the disease high up the school agenda.

The government in the United States, where swine flu was first seen in March in California, is not recommending school closures either, nor the widespread use of antiviral drugs such as Roche AG's Tamiflu or GlaxoSmithKline's Relenza to prevent spread. Doctors say they should be saved for people most at risk of complications or death -- pregnant women or people with asthma or diabetes.

Beijing H1N1 Conference: WHO predicts 'explosion' of swine flu cases

WHO predicts 'explosion' of swine flu cases

By GILLIAN WONG (AP) – 2 days ago

BEIJING — The global spread of swine flu will endanger more lives as it speeds up in coming months and governments must boost preparations for a swift response, the World Health Organization said Friday.

There will soon be a period of further global spread of the virus, and most countries may see swine flu cases double every three to four days for several months until peak transmission is reached, said WHO's Western Pacific director, Shin Young-soo.

"At a certain point, there will seem to be an explosion in case numbers," Shin told a symposium of health officials and experts in Beijing. "It is certain there will be more cases and more deaths."

WHO has declared the swine flu strain a pandemic, and it has killed almost 1,800 people worldwide through last week. International attention has focused on how the pandemic is progressing in southern hemisphere countries such as Australia, which are experiencing winter and their flu season.

But it is in developing countries where the accelerated spread of swine flu poses the greatest threat as it places underequipped and underfunded health systems under severe strain, Shin said.

Governments must act quickly to educate the public, prepare their health systems to care for severe cases and protect those deemed more vulnerable to prevent unnecessary deaths, he said.

"We only have a short time period to reach the state of preparedness deemed necessary," Shin said. "Communities must be aware before a pandemic strikes as to what they can do to reduce the spread of the virus, and how to obtain early treatment of severe cases."

Pregnant women face a higher risk of complications, and the virus also has more severe effects on people with underlying medical conditions such as asthma, cardiovascular disease, diabetes, autoimmune disorders and diabetes, WHO chief Margaret Chan said in a video address.

WHO earlier estimated that as many as 2 billion people could become infected over the next two years — nearly one-third of the world's population.

Health officials and drug makers, meanwhile, are looking into ways to speed up production of a vaccine before the northern hemisphere enters its flu season in coming months. Estimates for when a vaccine will be available range from September to December.

WHO has stressed that most cases are mild and require no treatment, but the fear is that a rash of new infections could overwhelm hospitals and health authorities, especially in poorer countries.

The last pandemic — the Hong Kong flu of 1968 — killed about 1 million people. Ordinary flu kills about 250,000 to 500,000 people each year.

Swine flu is also continuing to spread during summer in the northern hemisphere. Normally, flu viruses disappear with warm weather, but swine flu is proving to be resilient.

BMJ Editorial: Pandemic flu: will there be a second wave?

Pandemic flu: will there be a second wave?

Fiona Godlee, editor, BMJ

fgodlee@bmj.com

Rates of swine flu are levelling off in the northern hemisphere as summer progresses. The question now is whether we’ll have a second wave this winter, and if so how bad it will be.

Two evolutionary virologists writing in JAMA are cautiously reassuring (JAMA 2009;302:679-80). Looking back over the 14 or so pandemics since 1510, they say that pandemic flu has never been able to infect the entire population at once, and although it tends to recur after a first wave, it eventually adopts the familiar seasonal flu pattern.

As for A/H1N1, they say its modest transmission efficiency and its arrival in the northern hemisphere's early summer, as well as the degree of pre-existing population immunity from previous flu viruses and vaccines, all give reason to hope for a more indolent pandemic course and fewer deaths than in past pandemics. They don't think it's inevitable that the virus will mutate into a more virulent or contagious strain.

A second wave of A/H1N1 during the northern hemisphere's winter would coincide with its regular bout of seasonal flu, something the southern hemisphere is experiencing at the moment.

Melissa Sweet asks what lessons we can learn from Australia (doi:10.1136/bmj.b3317), and finds contradictory views among experts there. Some think the final death toll of A/H1N1 will be lower than for seasonal flu, noting that the big difference between now and 1918 is the availability of effective antibiotics. But others warn against being too dismissive. They are seeing respiratory failure of an unprecedented severity in young people, sparking concerns about how well intensive care will cope.

For me the wisest voice is that of Robert Booy. "We had both more severe disease and a huge amount of very mild disease, and people either played it one way or the other, and in doing so they either underplayed it or overplayed it, and the truth was somewhere in the middle." This fits with Heath Kelly's advice among a list of top tips for the northern hemisphere: "Be aware of the pandemic paradox: a high proportion of asymptomatic and mild cases but serious disease in the overweight and pregnant women."

If swine flu does come back with a vengeance, the UK may already have shot one of its bolts. Despite WHO advice to the contrary, in England the government opted for relatively indiscriminate use of antivirals after self diagnosis.

Could the government really not have provided more balanced information on the likely benefits and harms of antivirals and been more parsimonious?

Matthew Shun-Shin and colleagues updated and expanded an earlier Cochrane review on the effectiveness, safety, and tolerability of oseltamivir and zanamivir in seasonal influenza in children (doi:10.1136/bmj.b3172), information that must have been available to ministers when they were making their plans.

The evidence suggests that these two agents are of limited efficacy in children and are associated with a significant risk of side effects, mainly vomiting. Coupled with the risk of resistance and the financial cost of widespread use, these findings have led to calls to cut back the use of antivirals in mild flu and flu-like illness.

These calls are hard to ignore. Indeed, Hugh Pennington, emeritus professor of bacteriology at the University of Aberdeen, has told the media that Tamiflu may be useless by the autumn because of current indiscriminate use (http://tinyurl.com/qnsm4s).

According to news reports, ministers thought it would be publicly unacceptable to withhold antiviral drugs, even after it became clear that swine flu was generally a mild illness. Yet we know it's possible to educate patients and the public about the need to avoid unnecessary use of drugs, as last week's BMJ showed (BMJ 2009;339:b2885).