End of H3N2 Seasonal Flu Epidemic Declared in Reunion, with Virus A Accounting for 100% of Tested Cases

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Flu Cases Continue Downward Trend in Reunion Island

September 3, 2025

The number of emergency department visits related too influenza syndrome in Reunion Island has been steadily decreasing for the past five weeks. health officials recorded 84 such visits in the most recent reporting period, a 9% decrease from the 92 observed in the previous week.

This decline extends to hospital admissions, with 19 new cases admitted this week, down from 29. As of the latest data, influenza syndrome accounts for 2.3% of all emergency department activity, a slight dip from 2.5% the prior week.

Severe Cases and Viral Strain

Despite the overall improvement, serious cases of influenza continue to emerge. During the reporting period, 28 individuals required intensive care for a biologically confirmed influenza syndrome. A significant 75% of these cases were linked to the A(H3N2) influenza virus.

The median age of patients needing intensive care was 62 years, with a male-to-female ratio of 1.8 to 1. Importantly, all severe cases involved individuals with at least one pre-existing risk factor, such as active smoking or a pre-existing pulmonary condition. A quarter of the critically ill patients developed acute respiratory distress syndrome (SDRA),and tragically,one death was recorded.

Respiratory Infections in the Community

Monitoring of acute respiratory infections (IRAs) in primary care settings also indicates a downward trend. In the latest week, IRAs accounted for 5.6% of all community medical visits, compared to 6.5% the week before. This proportion,however,remains above the average observed between 2013 and 2024.

Virological Surveillance

Virological surveillance confirms a continuing decline in influenza virus circulation. Sixteen positive cases were identified in the last week, resulting in a positivity rate of 8.8%, down from 15.0% in the previous period. The A(H3N2) strain continues to be the predominant influenza virus detected, accounting for 100% of tested patients.

health authorities suggest that, should current trends continue, an official end to the flu epidemic could be declared in the coming weeks.

Metric	Current Week (S34)	Previous Week (S33)	Change
emergency Dept. Visits	84	92	-9%
Hospitalizations	19	29	-35%
Emergency Dept. % of Activity	2.3%	2.5%	-0.2%
ICU Admissions	28	N/A	N/A
Positive Cases	16	N/A	N/A

Did You know? Influenza viruses are constantly evolving. This is why annual flu vaccinations are significant to provide the best possible protection against circulating strains.

Pro Tip: Staying hydrated, getting enough rest, and practicing good hand hygiene remain crucial steps in preventing the spread of respiratory illnesses like the flu.

What measures are you taking to protect yourself and your family from the flu this season? Do you feel confident in the current public health response to influenza?

Understanding Influenza and it’s impact

Influenza, commonly known as the flu, is a contagious respiratory illness caused by influenza viruses.These viruses infect the nose, throat, and lungs. The severity of the illness can vary widely. While most people recover within a week or two, some can develop serious complications like pneumonia, bronchitis, and sinus infections.As highlighted in the data from Reunion Island, certain populations, such as those with underlying health conditions or who are older adults, are at higher risk of severe illness.

The World Health Institution (WHO) reports that seasonal influenza epidemics result in an estimated 290,000 to 650,000 respiratory deaths worldwide each year.

Frequently Asked Questions about Influenza

• What is influenza? Influenza is a viral infection that attacks your respiratory system, causing fever, cough, sore throat, and muscle aches.
• How can I prevent the flu? Vaccination is the most effective way to prevent the flu. Other preventative measures include frequent handwashing, avoiding close contact with sick individuals, and covering your mouth and nose when coughing or sneezing.
• What should I do if I think I have the flu? If you believe you have the flu,stay home,rest,and drink plenty of fluids. Consult a healthcare professional if your symptoms worsen or if you are at high risk for complications.
• Is the flu vaccine safe? Yes, flu vaccines are safe and effective. They are rigorously tested and monitored by health authorities.
• Can I get the flu even if I’ve been vaccinated? While the vaccine doesn’t guarantee complete protection, it significantly reduces your risk of getting the flu and can lessen the severity of symptoms if you do get sick.
• What is the A(H3N2) influenza virus? A(H3N2) is a subtype of the influenza A virus and is known to sometimes cause more severe illness, especially in older adults.
• How is influenza monitored? Public health agencies monitor influenza activity thru surveillance systems that track cases, hospitalizations, and viral strains.

Share this article with your network to raise awareness about influenza prevention and control. Leave a comment below to share your thoughts and experiences!

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What public health interventions were utilized during the H3N2 epidemic in Reunion Island?

End of H3N2 Seasonal Flu Epidemic Declared in Reunion: A Deep Dive

Current Situation & Key Findings – September 3, 2025

As of today, September 3, 2025, health authorities in Reunion Island have officially declared the end of the recent H3N2 seasonal flu epidemic. this announcement follows a sustained decline in reported cases over the past several weeks. Crucially, recent surveillance data reveals that 100% of tested influenza cases are now attributable to Influenza A viruses, specifically subtypes related to the H3N2 strain. this complete dominance of Virus A is a notable shift from earlier stages of the epidemic where mixed infections were observed.

This declaration signifies a return to typical seasonal influenza patterns, though ongoing monitoring remains vital. The rapid resolution is likely due to a combination of factors including increased population immunity and the natural waning of the H3N2 wave.

Understanding the H3N2 Strain & Its Impact

H3N2 is a subtype of Influenza A virus, known for its ability to mutate rapidly.This characteristic leads to antigenic drift, meaning the virus changes enough each year that prior immunity from vaccination or previous infection may not fully protect against the new strains.

Symptoms: Common symptoms of H3N2 influenza include fever, cough, sore throat, muscle aches, fatigue, and headache. Gastrointestinal symptoms, such as nausea and vomiting, are more frequently reported with H3N2 than with other influenza strains, particularly in children.

severity: While generally considered less severe than some other influenza strains (like H5N1 avian flu), H3N2 can still cause serious complications, especially in vulnerable populations.

Vulnerable Populations: Individuals at higher risk of severe illness from H3N2 include:

The elderly (65 years and older)

Young children (under 5 years old)

Pregnant women

Individuals with chronic medical conditions (e.g., asthma, diabetes, heart disease)

Immunocompromised individuals

The Reunion Island Epidemic: A Timeline

The H3N2 epidemic in Reunion Island began to gain momentum in late May 2025, with a noticeable increase in influenza-like illness (ILI) reported across the island.

1. May – June 2025: Initial rise in ILI cases, with a mix of Influenza A and B viruses detected.
2. July 2025: H3N2 becomes the dominant strain, accounting for over 70% of confirmed influenza cases. Hospitalizations begin to increase.
3. August 2025: Peak of the epidemic. Public health measures, including increased vaccination efforts and promotion of preventative hygiene practices, are intensified.
4. Late August – September 2025: A steady decline in cases is observed. Surveillance data confirms the shift to 100% Virus A dominance.
5. September 3,2025: Official declaration of the end of the epidemic.

Diagnostic Methods for Influenza A (H3N2)

Accurate and timely diagnosis is crucial for effective management of influenza cases. Several diagnostic methods are available:

Rapid Influenza Diagnostic Tests (RIDTs): These tests provide swift results (typically within 15-30 minutes) but have lower sensitivity compared to other methods.

Reverse transcription Polymerase Chain Reaction (RT-PCR): Considered the gold standard for influenza diagnosis, RT-PCR is highly sensitive and specific. It can also identify the specific influenza subtype (e.g., H3N2).

Viral Culture: Involves growing the virus in a laboratory setting. While highly accurate, it takes longer to produce results than RIDTs or RT-PCR.

Antigenic Testing: Detects the presence of viral proteins.

Public Health Response & Preventative measures

The successful containment of the H3N2 epidemic in Reunion Island was a result of a coordinated public health response. Key measures included:

Increased Vaccination coverage: Aggressive vaccination campaigns were launched, targeting vulnerable populations. The influenza vaccine is updated annually to match circulating strains.

Antiviral Medications: Antiviral drugs (e.g., oseltamivir, zanamivir) were prescribed to individuals at high risk of complications. These medications can reduce the severity and duration of illness if started within 48 hours of symptom onset.

Public Awareness Campaigns: Educational materials were disseminated to promote preventative hygiene practices, such as frequent handwashing, covering coughs and sneezes, and avoiding close contact with sick individuals.

Enhanced Surveillance: Increased monitoring of ILI cases and influenza-positive tests allowed health authorities to track the spread of the virus and adjust their response accordingly.

Isolation and Quarantine: Individuals with confirmed influenza were advised to isolate themselves to prevent further transmission.

The Importance of Ongoing Surveillance & Future Preparedness

While the current epidemic has ended, continued vigilance is essential. Influenza viruses are constantly evolving, and new strains can emerge at any time.

**Global Influenza