How does the world escape the 'dual pandemic'?

Scientists have discovered a theory that suggests that previous exposure to a respiratory virus helps the body to "be on the lookout" for similar pathogens.

Scientists have discovered a theory that explains why the Covid-19 epidemic and the flu never occur at the same time, even though public health experts have previously feared the world would face something called is a "double pandemic".

They argue that masks, distancing and other restrictions are only part of the reason why flu and other respiratory illnesses have disappeared during the Covid-19 pandemic.

Instead, exposure to a respiratory virus can put the body's immune system on high alert. The immune system will prevent other viruses from entering the respiratory tract.

This biological phenomenon, known as "viral interference", can limit the number of respiratory viruses circulating in an area at any given time.

"I don't think we're going to see the flu and Covid-19 peak at the same time," said Dr. Ellen Foxman, an immunologist at Yale School of Medicine.

On an individual level, she says some people can be infected with two to three viruses at the same time. But at the community level, according to this theory, one virus tends to dominate the others.

However, research into the interactions between viruses is still new, and scientists are struggling to understand how it works, according to the New York Times.

The number of flu cases is 'extraordinarily' low

Before Covid-19 became a global threat, influenza was one of the most common acute respiratory infections each year in the United States. During the 2018-2019 season, influenza resulted in 13 million medical visits, 380,000 hospitalizations, and 28,000 deaths.

The 2019-2020 flu season ended before Covid-19 started raging around the world, so it's still unclear how the two viruses affect each other. Many experts fear the viruses will cause a double pandemic next year.

Those worries did not materialize. According to the Centers for Disease Control and Prevention (CDC), despite slow vaccination, the number of cases remains unusually low throughout the 2020-2021 flu season when Covid-19 is spreading widely.

Wearing a mask is only part of helping to reduce the number of people infected with the flu.

Only 0.2% of the samples tested positive for the flu from September 2020 to May 2021, compared with about 30% in recent seasons. Hospitalizations are at a record low since the CDC collected data in 2005.

Many experts attribute this to the use of masks, distance and restrictions on movement, especially young children and the elderly - the group at risk of severe illness when contracting the flu. The number of flu cases increased a year later, into the 2021-2022 season, but the numbers are still well below the pre-pandemic average.

Covid-19 continues to be the dominant epidemic in winter, far more common than the flu, respiratory syncytial virus, rhinovirus or common cold virus.

Just the original theories

The idea that there is an interaction between viruses first emerged in the 1960s. Vaccination against polio, which contains a portion of the polio virus, significantly reduced the number of respiratory infections. .

The idea was raised again in 2009. Europe was prepared for an increase in H1N1 flu cases later that summer, but when schools reopened, the rhinovirus disease had already taken off. interrupt this.

Last year, a team of researchers investigated the role of the immune response in fighting the flu virus.

After administering a vaccine containing a weakened strain of the virus to a group of children, they noted a complex chain of immune responses, but the first line of defense came from interferon. The team found that children who had high interferon levels had much less flu virus than children with low interferon levels.

Previous viral infections have given a child's immune system a chance to fight off the flu virus.

This may partly explain the reason why children, who tend to have more respiratory illnesses than adults, are less likely to get SARS-CoV-2 virus.

Dr Guy Boivin, a virologist and infectious disease specialist at Laval University in Canada, said the flu could also prevent Covid-19 in adults.

Studies show that cases of both influenza infection and Covid-19 infection are very rare. He noted that if that individual is infected with the flu virus, they are nearly 60 percent less likely to test positive for Covid-19.

Studies show that cases of both influenza infection and Covid-19 infection are very rare.

Advances in technology have made it possible to pinpoint the biological basis of this interaction. Dr. Foxman's team used a human airway model to demonstrate that rhinovirus infection stimulates interferon against the SARS-CoV-2 virus.

Research by Dr Pablo Murcia, a virologist at the MRC Virus Research Center at the University of Glasgow, has similar results.

But Dr. Murcia also discovered another point in the virus interaction theory: Corona virus infection does not seem to prevent infection with other viruses. That may have to do with how good the SARS-CoV-2 virus is at evading the immune system's initial "defences," he said.

Compared with influenza, the SARS-CoV-2 virus tends to activate interferon less. This finding shows that in a given population, which virus comes first is quite important.

However, viruses can still be affected by their ability to evolve, social restrictions, and vaccination patterns. Therefore, the impact from the interaction between viruses will be more obvious until Covid-19 turns into a specific disease.

Looking at other coronaviruses that cause the common cold, some studies predict SARS-CoV-2 will become a seasonal winter infectious disease, coinciding with flu season. But Covid-19 shows itself to be far different from other "brothers".

Jeffrey Townsend, a biostatistician at the Yale School of Public Health who has studied coronaviruses and tracked the virus seasonally, said: 'This is an interesting example that makes many people hesitate to make statements. general conclusions about many viruses'.