Influenza: How to prevent and treat a serious infection

Published: October, 2008

This fall is different than any other before it. Back-to-school is different, professional and college sports are different, and many of the seasonal rituals are upended thanks to COVID-19. But what isn’t different is the return of influenza or the flu. The flu is more than a bad cold. Although many people who get the flu recover with rest and fluids, thousands of Americans die from this illness each year, and millions are sick enough to miss work or school. Influenza is serious — but it can be prevented and treated.

This flu season is complicated by worries about COVID-19. The same measures that help prevent the spread of the coronavirus — frequent and thorough handwashing, wearing a mask, not touching your face, coughing and sneezing into a tissue or your elbow, avoiding people who are sick, and staying away from others if you’re sick — also help to protect against spread of the flu.

Meet the flu bug

There are many influenza viruses. Nearly all cases of the flu are caused by human strains of the influenza A or B virus. Influenza A is the more serious strain. Because flu viruses change from year to year, having had the flu — or a flu shot — in a previous year won’t protect you this year. That’s why you need to get a new flu shot each year.

It is important to note that flu viruses are distinct from the coronaviruses that cause illnesses like COVID-19.

Influenza epidemics

In the U.S., the flu season runs roughly from Thanksgiving to Easter, with most cases occurring in the dead of winter. The Centers for Disease Control and Prevention estimated that during the 2018–2019 flu season an estimated 35.5 million people came down with the flu. Of these people over 16 million had to see their doctors, and over 30,000 people died from the flu.

Influenza is highly contagious

As a respiratory virus, influenza spreads on tiny droplets that spew into the air when you cough, sneeze, or simply exhale. People close at hand are the most likely to catch the flu, which is why the infection spreads so quickly through families, health care facilities, and other places where people live or work close to each other. The influenza virus can also be spread by hand-to-hand contact.

Why winter?

The flu loves winter. In the northern hemisphere, it comes around between November and March, but in the southern hemisphere, it hits from May to September, the coldest months. In the tropics, however, there is no true flu season — and very little flu.

Many respiratory infections peak in winter, when people cluster together indoors. But scientists found that the virus is transmitted much more efficiently in a cool environment. Low humidity provided another boost for the bug; in one study the virus spread much more readily at 20% humidity than at 80%.

Influenza symptoms

Influenza hits fast. After an incubation period of just one to two days, the influenza symptoms start abruptly. Most people run a fever, and high temperatures in the 103 F to 104 F range are common. Nearly everyone has a runny nose and sore throat, but unlike ordinary colds, the flu also produces a hacking, dry cough. Muscle and joint aches can be severe. Headache, burning eyes, weakness, and extreme fatigue add to the misery.

In most cases, the high fever and severe distress settle down in two to five days, but the cough can linger for a week or two and the fatigue even longer.

Influenza complications

The most serious — and deadly — complication is pneumonia. Young children, senior citizens, and people with chronic illnesses are at greatest risk. That’s why they have the greatest need for preventive vaccinations and medical treatments.

In some cases, pneumonia is caused by the flu virus itself. It’s a particularly deadly problem that begins early in the infection and progresses rapidly, with a severe dry cough and shortness of breath. Bacterial pneumonia is more common but more easily treated. It starts later, after a person seems to be on the mend. The fever returns and the cough increases, this time with thick, pus-laden sputum (phlegm).

Other flu complications can include asthma attacks, ear infections, bronchitis, sinusitis, inflammation of the heart or other muscles, and inflammation of the nervous system.

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