The 2025 flu season has turned out to be unlike any other in recent memory. This year, the flu season is marked by record-setting infections, multiple viral peaks, vaccine mismatches, and an overstretched healthcare system.

According to the Centers for Disease Control and Prevention (CDC), this year’s influenza activity is the most intense since the 2009 swine flu pandemic, with over 80 million estimated illnesses and rising. What’s driving this intensity, and what should the public know about prevention and symptom management?

Let’s break down what makes this flu season so severe and what it means for your health.

A Season Like No Other: What Makes 2025 Different?

In most years, flu activity in the U.S. typically follows a predictable pattern, starting in October, peaking between December and February, and fading by April. But the 2024–2025 season has defied that rhythm.

Cases surged past the national baseline in December and then, unexpectedly, peaked again in February, a second wave that blindsided doctors and public health experts.

As of March 2025, the CDC had reported an estimated 37 million influenza infections, 480,000 hospitalizations, and 21,000 deaths. Hospitalizations, in fact, reached their highest levels in 15 years.

One key driver? A mismatch between circulating flu strains and this year’s vaccine. The dominant strains: H1N1 and H3N2, accounted for more than 99% of cases.

H3N2, in particular, is known for mutating quickly and evading immune responses, and only about half of circulating H3N2 samples matched well with vaccine antibodies, according to CDC surveillance data.

Post-Pandemic Immune Gap

Another reason this year’s flu is hitting so hard: our immune systems are still catching up.

During the height of the COVID-19 pandemic, widespread masking, social distancing, and school closures suppressed not just SARS-CoV-2 but also seasonal flu and other common respiratory viruses. While that helped in the short term, it reduced community-level immunity over time, especially among children, who typically build natural resistance through repeated exposures.

“Young children who were toddlers or preschoolers during the pandemic missed early exposures to flu viruses,” explained experts at the nonprofit group Families Fighting Flu. “Now they’re in school, more socially active, and more vulnerable.”

The CDC reported a troubling spike in pediatric flu deaths this season with 216 fatalities, making it the deadliest flu season for children outside of a pandemic year. Neurological complications such as seizures and hallucinations also rose among young patients.

A Shift in Viral Dominance

Another unusual trend: COVID-19 has taken a back seat this winter

Unlike previous years when COVID-19 variants dominated respiratory illness charts, flu has surged ahead as the top driver of doctor visits and hospitalizations. This could be due to a shift in viral dominance, changing weather patterns, or differences in immunity buildup. According to the CDC, nearly 8% of all outpatient visits are currently for flu-like symptoms, much higher than what’s typical for this time of year.

Vaccine Fatigue and Gaps in Coverage

Vaccination remains the strongest tool we have to fight influenza, but uptake has been stagnant, or worse, declining, in key groups.

As of April 2025:

• Only 49.2% of children and 46.7% of adults had received the flu vaccine
• Among pregnant women, that number dropped to 38%
• Medicare beneficiaries aged 65+ had just 48.3% coverage
• And overall, nearly 9.2 million fewer doses were administered compared to the pre-pandemic 2019–2020 season

Barriers like vaccine hesitancy, misinformation, racial and ethnic disparities in healthcare access, and fewer flu shot clinics in rural areas continue to widen the gap.

What Are the Symptoms in 2025?

The 2025 flu has shown typical but often more intense symptoms than in previous years. Here’s what to look out for:

• Sudden onset fever
• Severe body aches and chills
• Sore throat and persistent cough
• Nasal congestion
• Diarrhea and vomiting (more frequent in children)
• Extreme fatigue
• Headache
• In some children, neurological symptoms like confusion or seizures

These symptoms may overlap with COVID-19 or RSV, but tend to come on faster and hit harder in flu cases this season.

How Long Do Symptoms Last?

For most healthy people, flu symptoms begin 1 to 4 days after exposure and typically last about 5 to 7 days. However, fatigue and cough may linger for up to two weeks.

You’re considered most contagious in the first 3 to 4 days after symptoms start but can continue to spread the virus up to a week later. The CDC recommends staying home until you’ve been fever-free for at least 24 hours without medication.

Vaccinated individuals may experience milder or shorter symptoms, but those with underlying conditions, young children, and older adults may have longer recoveries and higher risk of complications.

Can the Flu Cause Serious Health Problems?

Yes, especially in people with weakened immune systems, chronic illnesses, or no prior flu immunity.

Possible complications include:

• Pneumonia
• Ear and sinus infections
• Exacerbation of asthma or heart disease
• Life-threatening conditions requiring ICU care

This is why experts stress that prevention remains the best medicine.

How to Protect Yourself and Your Family

Here’s how to lower your risk during the remainder of the 2025 season:

• Get vaccinated, even now. It may still protect against circulating strains
• Wash your hands often with soap and water
• Avoid touching your face in public settings
• Cover your mouth and nose when coughing or sneezing
• Stay home if you’re unwell to prevent spreading the virus

When talking about fertility in routine practice, we usually refer to the World Health Organization’s guideline of roughly 15 million sperm per millilitre (and around 39–40 million total per ejaculate) as the lower boundary of “normal.”

But the count alone doesn’t tell the full story. The quality of sperm, their motility, shape, and the couple’s overall reproductive health are equally important. We got in touch with Dr. Meenakshi Priya, Clinical Director & Fertility Specialist, Nova IVF Fertility, Coimbatore, who told us more about the same.

What Is The Normal Sperm Count To Get Pregnant?

Dr Meenakshi said, “Think of sperm count like lottery tickets. More tickets (higher count) give you better odds, fewer tickets lower your chances — but even one well-functioning ticket (a motile, properly shaped sperm) can win.”

That’s why fertility clinics look at several factors: concentration, total number, progressive motility (whether sperm swim forward), and morphology (shape). The WHO manual provides the standard method and cut-offs used worldwide in labs, serving as the referee for semen analysis.

However, numbers matter clinically. Research over decades shows fertility starts to drop gradually below about 40 million/ml (or in older studies, 40 million total per ejaculate was a useful marker). The WHO threshold of 15 million/ml marks the lower edge of normal — values between 15 and 40 are a “grey zone,” where conception is possible but may take longer. So a man with 12 million/ml isn’t infertile, but the couple might need help like IUI or IVF depending on other factors.

But don’t get fixated on one number. A “normal” semen report is a combination of factors:

• Concentration ≥15 million/ml

• Total sperm count ≥39–40 million per ejaculate

• Progressive motility roughly >30%

• Normal morphology about 4% (Kruger criteria)

What Changes A Sperm Count?

Lifestyle and health have a big impact on sperm. Smoking, heavy drinking, extra weight, prolonged heat exposure (saunas, hot tubs, tight underwear), certain medications, recent fevers, and conditions like varicocele or hormonal imbalances can all lower the numbers.

The good news? Most of these are reversible. Dr Meenakshi said, “Quitting smoking, reducing alcohol, losing a bit of weight, avoiding hot tubs for a few months, and treating infections can improve sperm.” Remember, sperm take time to renew but it usually takes 2–3 months of healthier habits for improvements to appear in a report. Be patient; your body is making changes even if you don’t see results immediately.

When To Be Concerned And Consult A Doctor?

If semen analysis repeatedly shows very low sperm (oligozoospermia), no sperm (azoospermia), poor motility, or if a couple has been trying for a year (or six months if the woman is over 35) without success, it’s time to consult a specialist. One abnormal test isn’t the final word — tests are usually repeated, and a more thorough assessment may include hormone checks, ultrasounds, or genetic tests if needed.

Dr Meenakshi said, “Sperm count gives a headline, not the full story. It’s a useful screening tool, but fertility decisions are personal. If you’re concerned, get a proper semen analysis and speak with a fertility specialist — many fertility issues are treatable, and acting early makes a real difference.”

Norovirus, often called the stomach bug, has returned. Between August 1 and December 11, health officials recorded 268 norovirus outbreaks, with numbers climbing steadily as winter travel increases and more people spend time indoors. The virus triggers stomach-related symptoms such as nausea, vomiting, diarrhea, and abdominal pain or cramping.

Some people also develop fever, headaches, and body aches. Although case numbers are not rising as sharply as flu, doctors remain concerned because norovirus spreads extremely easily. Making matters worse, norovirus is difficult to kill. Many of the common precautions used against flu and COVID offer little protection against this so-called winter vomiting bug.

How Contagious Is the Norovirus?

Norovirus is among the most infectious viruses doctors deal with. “It can tear through a household and then circle back, with people repeatedly passing it to each other,” says Amy Edwards, MD, associate professor of pediatrics at Case Western Reserve University School of Medicine in Cleveland, Ohio, who specializes in infectious diseases. “It also spreads very quickly in crowded, closed settings like cruise ships.”

While contaminated surfaces can transmit norovirus, doctors say person-to-person spread is most common. An infected person can pass on the virus even before symptoms appear, throughout the illness, and after they start to feel better, Jennings warns.

What to Do If You Get Norovirus?

For most people, norovirus symptoms ease within a few days, according to Jennings. However, the illness can be more serious for those with weaker immune systems, including young children, older adults, and people with certain health conditions.

If you think you have norovirus, focus on staying well hydrated. Ongoing vomiting can quickly lead to fluid loss and electrolyte imbalance. To prevent nausea from getting worse, Jennings recommends taking small sips of clear fluids like water, ginger ale, or coconut water.

Most importantly, seek medical care right away if you become dehydrated or if diarrhea lasts for weeks. Fischer explains that dehydration may cause sunken eyes, less frequent urination, dry skin and mouth, and extreme tiredness.

Common Norovirus Symptoms That You Should Be Aware Of

Norovirus symptoms often come on suddenly and may include:

• Nausea
• Vomiting
• Stomach pain or cramps
• Watery or loose diarrhea
• General feeling of illness
• Mild fever
• Muscle aches

Symptoms usually begin 12 to 48 hours after exposure and last for one to three days. Even after recovery, people can continue shedding the virus in their stool for weeks. In some cases, especially among those with other medical conditions, shedding can continue for months. Some people infected with norovirus never develop symptoms at all. Even so, they can still spread the virus to others.

Norovirus Causes

Norovirus spreads very easily from one person to another. Because it is highly contagious, an infection can pass quickly through homes, schools, or other shared spaces. The virus is released through stool and vomit, and a person can spread it from the moment symptoms begin until several days after they feel better. Norovirus can also survive on surfaces and objects for days or even weeks.

You can catch norovirus by:

1. Eating food that has been contaminated
2. Drinking unsafe or contaminated water
3. Touching your mouth after your hands have come into contact with a contaminated surface or object
4. Having close contact with someone who is infected with norovirus

Norovirus is especially hard to get rid of because it can survive extreme hot and cold temperatures and is resistant to many common disinfectants.

The NHS has issued fresh advice for people taking a widely prescribed medicine used to manage heart and circulation conditions. Across the UK, millions rely on beta-blockers to treat heart and blood vessel problems. Each year, more than 50 million prescriptions are written for these drugs, which help manage issues ranging from high blood pressure and abnormal heart rate to certain conditions affecting the brain and nervous system. Doctors most commonly prescribe bisoprolol, which NHS England lists as the seventh most prescribed medicine in the country.

What Is Bisoprolol Used For?

Bisoprolol, sold under brand names such as Zebeta, Bisotab, and Concor, belongs to a group of medicines called beta-blockers. It is mainly used to treat various heart-related conditions by slowing the heart rate and relaxing blood vessels. This reduces strain on the heart and helps it pump blood more efficiently, according to the CDC. The NHS also explains that bisoprolol is used to prevent chest pain caused by angina and to manage atrial fibrillation and other irregular heart rhythms. By slowing the heart, it allows the heart muscle to work more effectively.

Data from 2024–25 shows that bisoprolol was dispensed around 32 million times in England alone. The NHS notes that for people with high blood pressure, taking bisoprolol can help lower the risk of future heart disease, heart attacks, and strokes.

Bisoprolol Side Effects: Why Is NHS Warning Against Bisoprolol?

Like most medicines, bisoprolol can cause side effects, and patients are advised to stay alert to them. People starting the medication are often told to take their first dose at night, as it can make some feel dizzy. There are several common side effects that affect more than one in 100 people. According to the NHS, these are usually mild and tend to settle over time. They include:

• feeling dizzy or sick
• headaches
• cold hands or feet
• constipation
• diarrhoea

However, there are less common but more serious side effects that should not be ignored, as they may require urgent medical attention. The NHS advises contacting a doctor or calling 111 if:

• you experience shortness of breath with a cough that worsens during physical activity, swelling in the ankles or legs, or an irregular heartbeat, as these can point to heart problems
• the whites of your eyes or your skin turn yellow, which may be harder to notice on darker skin tones, as this can signal liver issues

Bisoprolol Warning: When Should You See Medical Emergency

The NHS also urges people to seek immediate help if certain symptoms appear. These include:

• chest pain, which could indicate heart trouble
• shortness of breath, wheezing, or tightness in the chest, which may suggest lung-related problems

Emergency services should be contacted straight away if there are signs of a severe allergic reaction, known as anaphylaxis. The NHS says to call 999 immediately if:

• your lips, mouth, throat, or tongue suddenly swell
• you are breathing very fast or struggling to breathe, with wheezing or a choking sensation
• your throat feels tight or you have difficulty swallowing
• your skin, lips, or tongue turn blue, grey, or pale, which may be more visible on the palms or soles in people with darker skin
• you suddenly feel very confused, extremely drowsy, or dizzy
• someone collapses and cannot be woken
• a child becomes limp, floppy, or unusually unresponsive, with difficulty holding their head up or focusing

The NHS stresses that while bisoprolol is effective and widely used, knowing when side effects are harmless and when they signal an emergency is key to staying safe.