What would happen if a deadly flu pandemic broke out again?

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A century after the Spanish flu pandemic that killed nearly 100 million people, experts say that a new strain of the flu virus is as powerful as the strain of the virus that caused the Spanish flu pandemic is going inevitably emerge sooner or later.

At about the same time, in about 100 years, the flu season seemed to be over and about to leave. Most of those who contracted the disease in the spring were recovered and mortality rates were not higher than usual. The newspapers cared less about the flu than about the First World War.

• The story of an influenza pandemic that has not characterized the 20th century
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In the fall, however, the situation had changed. The usual virus has re-emerged as a severe strain, causing a pandemic that has hit North America and Europe and is killing thousands of people hours or days after the onset of injuries. Four months later, the outbreak, later known as "Spanish flu" in the world, broke out from below and even the most isolated communities were not delivered.

When the epidemic peaked in the following spring, the number of victims was estimated at 50-100 million, equivalent to five percent of the world's population.

A century after its outbreak, the Spanish flu pandemic may now look like other horrible epidemics to which we are immune after being declared totally or largely eradicated, such as the deadly smallpox pandemic or the plague.

In fact, the flu still kills 250,000 people out of 500,000 each year, and every year a new strain of the seasonal influenza virus appears, slightly different from the one before it. New strains may appear as a result of genetic exchange between the different strains of the influenza virus indoors. Host body and are more likely to spread and cause a general pandemic.

Unlike the 1918 Spanish flu, other influenza outbreaks spread over the next hundred years, in 1957, 1968, 1977 and 2009.

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Since influenza viruses are able to mutate and continue to be transmitted in the wild (wild waterfowl is a natural reservoir of the flu virus), experts agree that the flu virus is a natural reservoir. Emergence of a virus no less virulent than the Spanish flu virus – or perhaps even more lethal – is a matter of time.

"Influenza pandemics and pandemics, such as earthquakes, hurricanes and storms, are more lethal than others," said Michael Osterholm, director of the Center for Research and Infectious Diseases at the University. from Minnesota, but it is naïve to rule out a 1918 pandemic.

But it's impossible to predict when they will occur, says Osterholm. "The pandemic can start now, we do not know", it is impossible to know to what extent the conditions favorable to the emergence of a strain of the virus will be less ferocious than the strain of the virus that causes the pandemic of Spanish flu.

But we can speculate on the evolution of the epidemic based on the information we have collected about past pandemics.

Robert Webster of the Infectious Diseases Department of St. Jude Pediatric Hospital says the impact of the virus will depend on its surveillance before its spread. We have systems that allow us to quickly monitor viruses, such as the WHO Influenza Surveillance Team to monitor the evolution of the virus in six labs around the world. and the FAO Animal Influenza Network, which monitors the evolution of the virus in birds and pigs.

"It's of course free to control all the birds and pigs in the world, but we'd be very lucky if we could contain the virus before it's passed on," Webster said.

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Of course, says Webster, once infected, the virus will spread worldwide, probably in the coming weeks, given the level of migration and mobility of people.

"The flu virus is one of the viruses that, when it strikes the most vulnerable populations, causes epidemics and epidemics," said Gerardo Schweel, professor of epidemiology and statistics of Civil Status at Georgia State University.

Given that the world's population has quadrupled in the past 100 years, the number of victims and deaths should also increase in proportion to this increase.

If the 1918 flu virus kills 50 million people, the pandemic is now expected to cause 200 million deaths and injuries.

Mortality rates can vary from one country to another, with the Spanish influenza pandemic having increased 30-fold in several countries. The epidemic claimed the lives of 8% of the Indian population, for example, while less than 1% of Denmark's population was killed.

Similarly, in 2009, the swine flu virus in France caused 10 deaths in Mexico.

Experts attribute this disparity to several factors, including the public's acquisition of immunities against HIV because of its prior exposure to similar viruses, and the genetic differences that may make some breeds more vulnerable than D & O's. # 39; others. Maori, from New Zealand, for example, were more likely to die after infection with Spanish flu, seven times the world average.

Factors related to poverty, such as lack of hygiene and lack of health care, also exacerbate the effects of the influenza pandemic. "In 2009, many people went to the hospital only after the spread of the disease and the treatment was not working," Schweil said.

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The decision to go to the doctor was an economic decision for many initially, because it would mean getting a leave and thus depriving the salary of the working day.

If the epidemic is currently being invaded by the United States of America or other countries lacking health care systems that provide comprehensive health coverage to the entire population, the epidemic will impact those without health insurance for the same social and economic factors.

The victim who is not covered by the health insurance plan probably avoids going to the hospital because of the high costs of treatment and waits for his treatment to fail. "We have already seen this with other infectious diseases," Schweil said.

According to Lun Simonsen, an epidemiologist and infectious disease specialist at the University of Roskilde in Denmark and at George Washington University, vaccines are the best way to curb the spread of the epidemic. But this requires identifying the type of virus before preparing the vaccine and then distributing it around the world. This process can take months. If we can develop this vaccine, we will never be able to provide sufficient doses to the entire world population.

"Only 1 or 2% of the world's population is vaccinated in the first six to nine months of development, and the currently available seasonal flu vaccines are only 60% effective," Simonsen said.

"There is a shortage of antiviral products even in the United States, which is the richest country in the world, not to mention India, China and Mexico," said Mr. Chowwell.

In addition, Webster says that the available drugs are less effective at treating influenza viruses than drugs similar to those used for other diseases, because the world is sick of seasonal flu.

"It is only after a serious pandemic, as with HIV, that the disease attracts the attention of the scientific community."

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According to Austerholm, in light of these data, if a pandemic occurred at the moment, hospitals would be unable to absorb the number of patients and the drugs and vaccines would deplete immediately.

"The number of patients in the flu season this year has exceeded the capacity of the health system to absorb it, even though it was not an exceptional season, but it shows how limited our systems are in responding to the large number of cases, "he said.

As in 1918, entire cities around the world risk being paralyzed by the growing number of casualties and deaths. Businesses and schools could close, public transport would stop, electricity could be cut off and corpses would accumulate on the roads.

Food is soon scarce and millions of patients depend on millions of patients to survive, such as diabetes, heart medications and immunosuppressive drugs.

"If the epidemic does not produce or transport these drugs, many people will not die because of their lack," he said.

Even after the eradication of the virus, we will continue to suffer the consequences for many years. Simonsen claims that 95 percent of the victims of the 1918 flu pandemic were neither elderly nor children, but were at the very beginning of their youth and that they not only had devastating consequences for them. families, such as orphans of countless children, but also a huge shortage of manpower.

Scientists have not discovered why the virus had been eradicated in young adults before 2005, when researchers studied the genetic makeup of the Spanish flu virus with the help of salvaged samples. the town of Previg, Michigan, Alaska, which had killed 72 people on 80 D a week.

A microbiologist was able to extract the virus genes from the lungs of a victim, which helped the still layer preserve its body.

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In 1918, by synthesizing the influenza virus and injecting it into laboratory animals, scientists discovered that this strain multiplied so rapidly that it caused a natural immune response called cytokine secretion syndrome. . Chemicals supposed to eliminate superfluous objects that invade the body.

These cytokines themselves cause bodily harm and are responsible for the pain and stiffness of the seized patient, and the doubling of the body can prevent normal body function, resulting in multiple organ failure.

Researchers believe that the strong immune system of young people has generated a strong reaction to the virus, which may have led to their deaths. "We have finally understood why this virus is so virulent that it can kill the patient," says Webster. "It forces the body to kill itself."

In recent decades, researchers have developed many treatments based on altering the immune response that can help reduce secretion secretion.

But these treatments are flawless and have not been widely recognized. "Since 1918, we have not developed effective treatments to inhibit excessive immune response to the influenza virus or the cytokine storm, with the exception of ventilators or blood pumps in the body. body likely to prolong the life of the patient, the overall results of years of research and development are not promising, at all. "

This means that in case of pandemic influenza intensity equivalent to that of 1918, its victims will also be younger, but the consequences of the decline in the number of young people after the increase in the number of young people. Life expectancy in recent decades will be more severe than those of the last century. Economy or society.

Despite all this pessimism, there is a glimmer of hope in the development of a comprehensive flu vaccine that offers long-term protection against a wide range of influenza viruses.

Large sums of money were mobilized to realize this dream, long sought by researchers, and mobilized considerable energy to develop it after its reverberation around the world.

"The researchers are currently experimenting with the development of this vaccine, and we hope that they will achieve it before the advent of the deadly virus, but now, in anticipation of the emergence of the pandemic vaccine, we are not ready to have one at all, "said Webster.

You can read the original article on BBC Future

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