Why is the COVID-19 surge so kicking in in the U.S.? The American response to the outbreak of respiratory syncytial virus
But COVID-19 restrictions started being lifted last year. Why is the surge only kicking in now? Hensley was concerned that flu and RSV would rebound last year. It was a relatively good influenza season in the Northern Hemisphere. And although RSV infections did rise, the peak was lower than in pre-pandemic years and came in the summer of 2021 — odd timing that might have helped to dampen the spread of the virus. Virginia Pitzer, an epidemiologist of the Yale School of Public Health in New Haven, Connecticut, says that the peak of the Respiratory syncytial virus was not very favorable because of factors such as temperature and humidity.
The first hint of what could be in store is what’s happening in Europe. Infections have been rising in many European countries, including the U.K., France, and Italy.
“In the past, what’s happened in Europe often has been a harbinger for what’s about to happen in the United States,” says Michael Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota. I think the bottom line is that we need to be ready for what’s going to happen in Europe.
Germany and France are seeing increases as we speak, according to the director of the UT COVID-19 Modeling Consortium at the University of Texas at Austin. That gives me some pause. It adds uncertainty about what we can expect in the coming weeks and the coming months.”
According to Lessler, there’s a chance the U.S. experience will differ from Europe’s.
That’s because it’s not clear whether Europe’s rising cases are related to people’s greater susceptibility to new subvariants they’ve not yet been exposed to. Different countries have different levels of immunity.
“If it is mostly just behavioral changes and climate, we might be able to avoid similar upticks if there is broad uptake of the bivalent vaccine,” Lessler says. If the U.S. is immune escape across several variant’s with convergent evolution, the outlook for the nation could be more concerning.
“It’s really too early to say something big is happening, but it’s something that we’re keeping an eye on,” says Amy Kirby, national wastewater surveillance program lead at the Centers for Disease Control and Prevention.
There hasn’t been a strong increase in US deaths or hospitalizations because of the high flu numbers.
“We’re seeing the northern rim of the country beginning to show some evidence of increasing transmission,” Rubin says. “The winter resurgence is beginning.”
Assuming no dramatically different new variant emerges, it appears highly unlikely this year’s surge would get as severe as the last two years in terms of severe disease and deaths.
“We have a lot of immunity in our population compared to last winter,” says Nuzzo, the Pandemic Center’s director.
People have gotten vaccinations, but also many people have gotten this virus. Some people have gotten it more than once. It builds up immunity and reduces the risk of severe illness in the population.
How many people get one of the new bivalent omicron boosters could affect the impact of a rise of infections.
But booster uptake in the U.S. was already sluggish. “Nearly 50% of people who are eligible for a booster have not gotten one,” says William Hanage, an associate professor of epidemiology at the Harvard T.H. Chan School of Public Health. “It’s wild. It’s really crazy.”
So far the demand for the new boosters has been slow. Less than 8 million people have gotten one of the new boosters since they became available over the Labor Day weekend even though more than 200 million are eligible.
Given the likelihood of a surge, it’s critical people up to date on vaccines, says Nuzzo. “The most important thing that we could do is take off the table the possibility of this virus causing severe illness and death,” she says.
The spread of respiratory illnesses was blunted by the restrictions placed on COVID-19. Influenza and Respiratory syncytial virus (RSV) can cause mild cold-like symptoms in young children and older adults, but that can be dangerous, and most of them will be gone by the start of 2021. Now, in the Northern Hemisphere, RSV is surging, and the hospitalization rate for flu in the United States is higher for this time of year than it has been since 2010. There are questions about why these surge are happening now. And what’s in store for future winters?
It is not clear whether the number of flu cases in North America will continue to climb throughout December and January, creating a larger than usual disease burden, or whether a rapid increase early in the season will mean that the epidemic starts to decline earlier than usual.
The Anatomy of Seasonal Flu: Why the First Flu Surge Didn’t Start Unnoticed by the Francomanian Immunity Debt
Hensley says that this is because the population “is more immunologically naive than what we would expect in most years”. Normally, children get infected by their second birthday. You will end up having children that are three, four, years of age who have never seen the movie.
In August 2021, researchers in France coined the term ‘immunity debt’ to describe this reduction in population-level immunity. On Twitter, the term has taken on a life of its own. Matthew Miller, an immunology researcher at the University of Hamilton in Canada, thinks that the idea that lack of exposure to pathogens has irrevocably damaged the immune system is nonsense.
There is also a lot that researchers still don’t understand about seasonal viruses. For example, COVID-19 restrictions seemed to have little impact on one type of seasonal virus, rhinoviruses — which are the most common cause of colds — for reasons that aren’t entirely understood. That might be because of their hardiness, Miller says. They are less prone to desiccation and can last longer in the environment.
Another open question is how these viruses compete and interfere with one another. Infection with one virus can raise a strong innate immune response that might prevent infection with another virus. Hensley states that the first wave of flu decreased after the Omicron surge began. Maybe Omicron provides some short-lived protection against flu. Or maybe the Omicron surge simply convinced people to mask up and keep their distance.
The last unusual winter in the United States, a forecast from a congressional influenza pandemic and the US Centers for Disease Control and Prevention
Pitzer thinks that the peaks and valleys of next year might look a lot like those in the past. She is not placing bets. She predicts that this winter is going to be the last unusual winter.
Flu surged in the United States after Thanksgiving, bringing the most severe week yet in a season that hit the county extra early. The number of flu cases jumped nearly as much as the number of flu hospitalizations in the past week.
The CDC says that all but seven states are experiencing high or very high respiratory virus activity. States with moderate, low, or minimal activity are Alaska, Hawaii, Michigan, New Hampshire, South Dakota, Vermont and West Virginia.
Data from Walgreens that tracks prescriptions for Tamiflu and other flu treatments suggests that flu hotspots spread from El Paso to southwest Virginia.
Hospitals are more full now than they’ve been throughout the Covid-19 pandemic, according to a CNN analysis of data from the US Department of Health and Human Services.
The statement says that work force shortages have made it more challenging for hospitals, but also reduced the number of patients who can be cared for in nursing homes. Patients are spending more time in hospitals, awaiting discharge to the next level of care and limiting the ability to make a bed for a patient who truly needs to be hospitalized.
There are at least ten times the normal rate of children being hospitalized for seasonal influenza in Canada at this point in the year, causing worry among clinicians and parents. In late November, weekly admissions were 50% higher than the previous record peak for at least the past seven flu seasons.
The US Centers for Disease Control and Prevention (CDC) estimates that there have been 7,300–21,000 flu deaths in the country so far this season, with 21 reported paediatric deaths. No one knows how much further numbers will rise.
Flu largely disappeared at the height of the COVID-19 pandemic because non-pharmaceutical interventions such as mask wearing, school closures and social distancing squashed transmission of influenza viruses. Health officials expected the illness to come back when these measures were phased out.
A(H3N2) is also more severe than other common strains: it has caused more than twice as many hospitalizations over the past six flu seasons as another common subtype, A(H1N1), which caused the 2009 ‘swine flu’ pandemic. The 2017–18 US flu season — the country’s worst for more than a decade — was also dominated by A(H3N2). This resulted in 710,000 hospitalizations and 52,000 deaths in the United States, including more than 500 children.