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“Flu” is short for “influenza,” a contagious viral infection that can present with both mild and severe symptoms.
The influenza virus sticks around throughout the year but becomes particularly active during specific months that are collectively termed as the “flu season.”
In the United States, the flu season generally spans from December to February but can extend to as late as May.
The intensity of the flu epidemic can be assessed from the mortality surveillance data updated on June 12, 2020, by the National Center for Health Statistics (NCHS). The figures show that pneumonia and influenza were responsible for as many as 5.2% of the deaths during the end of the 40th week. (1)
How Does the Flu Spread?
The flu is an easily communicable disease that can be contracted through direct or indirect contact.
People infected with the flu can release aerosolized droplets of saliva containing the virus while speaking, coughing, sneezing, or breathing. These droplets travel through the air and land on any object or person in their trajectory.
- Direct transmission: Involves inhaling the infection-carrying droplets
- Indirect transmission: Involves picking up the virus on your hands by touching contaminated surfaces and then transferring it to your nose or mouth
Flu symptoms set in gradually, so you may not be able to tell if a person has the infection initially.
Even though the symptoms are latent in the early days, the virus is not. Thus, someone who has contracted the flu can spread it to others even when the symptoms are absent.
The Flu Cycle
The influenza virus finds its way into your body through nasal or oral passages without you realizing it.
The virus travels to the lungs where it develops into a full-blown infection. At this incubation stage, the infection presents no visible symptoms but is already contagious.
You may experience an occasional sniffle, but there is virtually no way of knowing that you have contracted the flu.
You are overcome by a general feeling of being unwell. The only way to reduce the length of your illness is early treatment during the first 2 days after the symptoms hit you.
The symptoms peak as the infection enters its 6th day. By this time, the virus has completely taken over your immune system, and there is little you can do to lessen the intensity of the illness over the next few days.
It is during the climactic phase of the flu period that the body begins to manufacture the antibodies required to defeat the virus.
As the immune system puts up a better fight, your symptoms begin to diminish gradually. The fever and coughing gradually reduce, until they completely cease in a matter of days.
Signs and Symptoms
A sudden onset of fever that is usually above 101°F or 38.3°C is usually the first sign of the flu, which is often followed by the following symptoms:
However, not everyone with the flu will have a fever.
Flu is a viral infection that will resolve on its own after running its full course, but you can use the following medical interventions to shorten the flu cycle or prevent the flu infection altogether.
1. Antiviral drugs
Prescription medications called antiviral drugs can be used to treat the flu.
One of the most commonly used flu medications is oseltamivir, which is FDA approved and available in both pill and liquid forms. This antiviral drug is safe for anyone from 2 weeks of age and older and is usually administered during the early stages of the condition. (2)
2. Influenza vaccine
The choice of vaccine usually varies for different age groups. For instance, the regular flu shot is considered safe for anyone above the age of 6 months.
The intradermal flu shot is mostly recommended to adults between the ages of 18 and 64 years of age.
Moreover, a person may be allergic to a particular vaccine or some of its content, which calls for a safer alternative. The influenza virus changes antigenicity frequently, so seasonal flu vaccines have to be updated almost annually.
Cold vs. Flu
Cold and flu have similar symptoms, but these viral infections are different in several aspects:
- While there are over 200 types of viruses that can cause a cold, the flu infection is usually caused by two types of viruses, namely, influenza A and B. Both these infections affect the respiratory system, but the symptoms associated with the common cold are generally milder than those of the flu.
- The onset of symptoms is much more gradual in the case of the common cold, starting with a runny or stuffy nose, sneezing, and a sore throat. Flu symptoms, on the other hand, come on very quickly and intensely in the form of extreme tiredness, fever, body aches, and cough.
- Although most prevalent in winters, a cold can be contracted at any time of the year. The flu season, however, stretches from December through February.
All things considered, the flu is typically worse than a cold and can lead to pneumonia, bacterial infections and other health complications that may warrant prescription medications and sometimes even hospitalization.
Given that symptoms are often insufficient to tell the two conditions apart, your doctor may conduct special tests within the first few days of the illness to identify if it is the flu or merely a cold.
People at High Risk of Getting the Flu
The following groups are more vulnerable to the flu virus and should exercise extra precaution against it:
- Older adults who are aged 65 years or older
- Pregnant women
- Young children (<5 years of age)
- People with diabetes
- People with a history of stroke
- People with HIV/AIDS
- People with cancer
- Children with neurodevelopment disorders
Here is a list of complications associated with the flu:
- The most common complication associated with the flu is pneumonia. This happens particularly in cases when a viral-based influenza infection triggers a secondary bacterial infection in the body that can be caused by strains such as Haemophilus influenzae or Streptococcus pneumoniae.
- The influenza virus can also aggravate other chronic medical conditions such as pulmonary diseases and asthma.
- In some cases, the flu can pave the way for sinus and ear infections.
- A particularly severe infection can induce a major inflammatory response in the body and may lead to sepsis if the virus enters the bloodstream.
- Another serious complication associated with a bad case of flu is inflammation of the heart or myocarditis.
- Flu can even trigger encephalitis or brain fever.
- The influenza virus can trigger inflammation in your muscle tissue, leading to myositis and rhabdomyolysis.
- In extreme cases, the flu infection can cause your organs to shut down (for example, respiratory and kidney failure).
When to See a Doctor
If you have the slightest inkling that you may be coming down with the flu, it is important to get yourself evaluated by a doctor.
Expert Answers (Q&A)
Answered by Dr. Daquesha C. Chever, DO (Family Physician)
In general, flu symptoms can last for 3–7 days. In extreme cases, the symptoms can last up to 2 weeks.
Taking oral doses of vitamin C will not protect you from contracting the flu. However, as a powerful antioxidant, vitamin C can help protect and strengthen your immune system.
Staying hydrated is probably the most important thing you can do, especially if you are running a fever. You can drink water, coconut water, or electrolyte-containing sports drinks for hydration.
Eating foods rich in antioxidants and vitamin C can give your immune system a much-needed boost when you are sick.
No, the flu virus mutates (changes) from year to year. Therefore, you need to get a new seasonal flu vaccine each year to be protected against the newly evolved strain of the virus. In addition, the antibodies your body makes to the flu shot decrease over as time passes.
The bad news is people who were vaccinated can still contract the flu. Flu infection in these people can happen for several reasons, including whether or not they received the appropriate dose of vaccine for their age, when they received their flu vaccine (timing), and the condition of their health at the time of vaccination.
The good news is that the symptoms are typically milder and the course of illness is shorter for those who received the vaccine than those who did not.
• Have everyone in your family including yourself get the flu shot. The flu shot is available for individuals 6 months and older. It is also recommended for all pregnant women.
• Cough or sneeze into your hands or elbows to decrease the spread of germs to others.
• Practice good hand hygiene and wash your hands often with soap and water for at least 20 seconds.
There are prescription medications that can decrease the flu symptoms and shorten the duration of illness. These medications work best if you start them within 48 hours of developing your first flu symptom.
However, mild cases of the flu can be treated at home with fever reducers, anti-inflammatory medications, rest, and fluid hydration. Please see your doctor if your flu symptoms are not responding to traditional over-the-counter medications.
It is also recommended to seek medical care if the more severe symptoms, such as decreased urine output (a sign of dehydration), severe muscle pain, difficulty breathing, fever over 104°F, decreased alertness, dizziness, confusion, fast or troubled breathing, chest or rib pain, fever, or cough, initially improved and then worsened again.
Wash your hands while singing the Happy Birthday song.
Flu is a common illness that spreads periodically and affects a considerable number of people each year. Although this infection can be managed easily with early interventions, it can sometimes take a turn for the worst.
The influenza viruses hijack the respiratory system and can cause breathing difficulties in severe cases that may warrant hospitalization. In fact, considering the global toll of this epidemic, it accounts for a large number of deaths each year. Hence, the importance of yearly vaccination against such infections cannot be stressed enough.
If you do contract the infection, prompt treatment with antiviral drugs will keep it from getting worse and facilitate early recovery.
Overcoming the flu will most likely render you immune to that particular strain of the virus, but you are still vulnerable to other flu strains. So, you must stay abreast of the necessary preventive and self-care measures to protect yourself from this viral infection.