At one point last month, children were admitted to Yale New Haven Children’s Hospital with an astonishing range of seven respiratory viruses. They had adenovirus and rhinovirus, respiratory syncytial virus and human metapneumonia, influenza and parainfluenza, as well as coronavirus – which many experts say is responsible for the unusual outbreaks. “This is not typical for any time of year and it is certainly not typical in May and June,” said Thomas Murray, an infection control specialist and associate professor of pediatrics at Yale. Some children admitted to the hospital became infected with two viruses at the same time and some with three, he said. More than Two years after the coronavirus pandemic, the viruses in question act in unknown ways. Respiratory syncytial virus, known as RSV, usually limits its suffocating attacks to the winter months. The rhinovirus, which causes the common cold, rarely sends people to the hospital. And the flu, which seemed to return in December after not appearing last year, disappeared again in January as soon as the Omicron variant of the coronavirus prevailed. Now the flu is back, but without a common genealogy known as Yamagata, which has not been identified since early 2020. It could have disappeared or may be waiting to attack our unsuspecting immune system, the researchers said. Monitoring of coronavirus cases The disturbance is felt in hospitals and laboratories. Doctors are reviewing routines, including keeping preventive shots in the spring and even summer. Researchers have a rare opportunity to find out if behavioral changes such as home-based orders, coverage and social distance are responsible for the virus shifts and what evolutionary advantage SARS CoV-2 can have over its tiny rivals. “It’s a huge natural experiment,” said Michael Mina, an epidemiologist and lead scientist at the eMed digital health platform. Mina said the change in seasonality is largely explained by our lack of recent exposure to common viruses, which makes us vulnerable to their return. In hospitals across the country, doctors are adapting protocols that for decades reflected a predictable cycle of illnesses that would come and go when schools closed or the weather changed. “You would see a child with a febrile illness and you would think ‘What time of year is it?’ Said Peter Hotez, a molecular virologist and rector of the National School of Tropical Medicine at Baylor College of Medicine in Houston. For years, Teresa Burton, head of pediatric infectious disease at the University of San Antonio Health, regularly advocated for the flu vaccine each fall and relaxed her advocacy until March and April, when the flu disappeared. The new change in seasonality, with flu cases rising last summer and then again this spring, made her think again. “You’re like, ‘Oh dude!’ Can you get a Covid booster and a flu shot? Here’s what you need to know. She and other infection experts are also reviewing their response to RSV, a common virus that treats about 60,000 children under the age of five each year, according to the Centers for Disease Control and Prevention. It can cause fatal lung infections in premature and other high-risk infants. The typical treatment for them is the monthly intake of a monoclonal antibody, palivizumab, from about November to February. But last summer, the RSV was suddenly launched and this year is causing problems in May and June. Infectious disease specialists are closely monitoring the cases so that they are ready to reactivate the expensive protocol. “We are monitoring the number of cases, so if it exceeds one, we are ready,” Murray said. Yale Hospital, which usually holds meetings to prepare for the upward spirals from fall to spring, prepares pandemic-tired staff for out-of-season outbreaks. Even the common cold looks a little more aggressive and resilient, according to Richard Martinello, a respiratory virus specialist at Yale Medical School. “When people get cold, it seems to be a little worse,” he said, noting that so far the figures are largely anecdotal. The changes – and how and when they can return to normal – reflect changes in our behavior during the pandemic as well as the interaction between SARS CoV-2 and other viruses known as viral interference. We have evolved alongside pathogens and our regular contact with them usually allows our immune system to recover the response without making us very sick. The system has “enough memory to make it more like a good rich souvenir than a bad one,” Mina said. The moment you stop seeing a virus at this normal rate, as happened during the pandemic, this natural balance is disturbed, Mina said. The emergency measures we have taken to reduce exposure to the coronavirus – necessary measures to curb a deadly new enemy – have also reduced our exposure to other viruses. If you are exposed to a virus again after a long time, you may not be able to protect yourself as well, leading to out-of-season increases in the entire population and surprisingly infections to individuals. That, Mina and others say, is what happened when people took off their masks and started concentrating indoors. The viruses began to circulate out of season, because the immunity of the population was low even if other conditions for them were not optimal. “All of these decisions have consequences,” Murray said. “You do the best you can with the information you have.” The same process of immune memory is already well documented by other phenomena, Mina said, such as 35- to 40-year-olds with shingles, a reactivation of the chickenpox virus that usually affects the elderly or people with weakened immune systems. Before the onset of chickenpox vaccines, people typically became infected as children and then had a series of natural boosting events throughout their lives, restarting their immune system as they came in contact with infected friends and then their own. children and their children’s friends. Now that these children are protected, they do not provide their parents with these natural aids, making these adults vulnerable to the virus again in the form of shingles. This phenomenon will be short-lived, as young people who are protected by the chickenpox vaccine will age and will not be at risk of contracting shingles. While vaccines disrupt the viral landscape by limiting the spread of infections, during the pandemic an entirely new virus – SARS Cov-2 – does so by interacting with its most common rivals. It is not yet clear whether the fall in flu cases in January, for example, was caused entirely by people retreating as the omicron spread or whether the coronavirus acted to sideline its most common adversary through someone else. mechanism. “It’s a wonderful question, if the micron pushed it away,” said Xiaoyan Song, head of infection control at the National Children’s Hospital in the region. Even more mysterious is the role Covid played in getting Yamagata out of the game. When the flu returned this spring, this genealogy was nowhere to be found. Ellen Foxman, an immunobiologist at Yale School of Medicine, has spent years researching how viruses interact and which genetic and environmental factors mean that the same virus can cause one person to catch a cold and another to become ill. It is a high-tech company that uses cells from the nose and lungs to grow human airway tissue in the laboratory before infecting it with viruses, along with environmental pollutants such as cigarette smoke. The study of the lining of the nasal passages has provided information on what is known as innate immunity. Once these cells detect a virus, they activate the antiviral defenses, blocking other viruses. This process may explain why the long-awaited bipolar disorder of coronavirus and other viruses, which was probably hampered by remote work and coverage in the winter of 2020 to 2021, did not occur last winter, despite sporadic co-infections. The group of babies born in the last two years will provide a lot of information. Normally a child under 5 years old has an average of one virus in his nose 26 out of 50 weeks of the year. Severe RSV and rhinovirus Infections in those early years are associated with the development of asthma later in life. “These children did not have an infection at a critical time in their lung development,” Foxman said, making it essential to understanding the link between a viral infection and asthma. However, it is not clear what the future holds, as Covid settles in between us. “It will take time, even years, to see what the new balance will be like,” Martinello said. Mina expects the coronavirus, like other respiratory viruses, to fall into a seasonal circulation pattern once the population’s immunity increases, reducing what is known as a “contagious force”. “When you have a lot of people who do not have immunity, the impact of the season is smaller. “It’s like a free reins,” Mina said. The virus “can overcome seasonal barriers”. All of these changes will be influenced by other environmental factors, Barton says, as climate change changes seasonal weather patterns. Despite these continuing uncertainties, for many researchers the pandemic-induced disturbance has reinforced known strategies for preventing infection. Scott Hensley, a microbiologist at the Perelman School of Medicine at the University of Pennsylvania, is not convinced that Yamagata flu is gone forever. It may still be circulating, undetectable, at very low levels, he said, ready to reappear on stage. However, there is a tried and true method of protecting ourselves – through vaccination. “Even in years when vaccines do not fit, there is a level of protection,” Hensley said, “preventing hospitalization and death.” For Foxman, the laboratory scientist, the pandemic …
