Common cold vs. flu (Influenza)

The common cold is a non-harmful, self-limited syndrome (disease whose natural history is to resolve without treatment) representing a group of diseases caused by members of several families of viruses.

The term ‘common cold’ refers to a mild upper respiratory viral infection involving nasal congestion, discharge, sneezing, sore throat, cough, low-grade fever, headache, and malaise.

Seasonal influenza is an acute respiratory illness caused by influenza A or B viruses. Influenza occurs in outbreaks and epidemics worldwide, mainly during the winter season.

What are the common respiratory infections around us?

• Respiratory syncytial virus (RSV) is a highly contagious, seasonal lung infection. It’s a common childhood illness that can affect adults too. Most cases are mild, with cold-like symptoms. A severe infection leads to pneumonia and bronchiolitis. RSV causes seasonal outbreaks of respiratory tract illness throughout the world, usually during the winter season. It is common among children, but is also an important and often unrecognised cause of respiratory tract infection in older adults.

During the coronavirus (COVID-19) pandemic, mitigation measures (e.g., mask wearing, physical distancing, school closure) were associated with marked reductions in ‘non-COVID-19 respiratory infections’ in children, including RSV, during the winter season. However, relaxation of mitigation measures led to rise in RSV infections among children.

RSV is the most common cause of lower respiratory tract infection (LRTI) in children under one year of age. RSV infects almost all children by the time they are 2 years old; children older than 5 years and adults may not have any symptoms of RSV, or they will have very mild symptoms.

If a child or adult does get symptoms of RSV, they are like symptoms of the common cold. It’s possible to get RSV more than once in your lifetime and even more than once during a single RSV season. Repeated infections tend to be less severe than the first infection. Repeat RSV infections in older children and adults may cause tracheobronchitis or other types of lower respiratory tract disease – using good hygiene prevents the spread of RSV.

• Common cold − Common cold can be caused by several different viruses, including rhinoviruses, parainfluenza, and common cold coronaviruses. In general, compared with influenza, cold symptoms are usually milder; nasal congestion is more common, and colds rarely result in serious health problems or complications.
• Acute Bronchitis (Bacterial or Viral) – Bronchitis is when the airways leading to your lungs (trachea and bronchi) get inflamed and fill with mucus. You get a nagging cough as your body tries to get rid of the mucus. Your cough can last two or more weeks; your chest can pain with coughing. Acute bronchitis is usually caused by a virus or bacteria.
• Cough variant Asthma and Asthma episodes – Cough variant asthma is a type of asthma that features a dry, nonproductive cough. There may be no traditional asthma symptoms, such as wheezing or shortness of breath. An ongoing irritable dry cough is often the only symptom. Exposure to allergens or irritants, a cold or upper respiratory infection, exercise and change in the weather…are all triggers. Also, people with history of Asthma can get it triggered with cold, allergens and associated infections.
• Seasonal influenza infection –Influenza viruses are spread from person to person, through contact with respiratory secretions (sneezing, coughing, talking, touching). It spreads actively in children. High grade fever, dry cough, running nose, headache and body pain are main symptoms. The spectrum of clinical manifestations and the severity of infection can vary with different types of influenza and is often mild in vaccinated individuals.

Influenza (flu) is a contagious respiratory illness caused by influenza viruses that infect the nose, throat, and lungs. Some people, such as people 65 years and older, young children, and people with certain health conditions, are at higher risk of serious flu complications. There are two main types of influenza (flu) viruses: types A and B. The influenza A and B viruses that routinely spread in people (human influenza viruses) are responsible for seasonal flu epidemics each year. The best way to reduce the risk of flu and its potentially serious complications is by getting vaccinated each year.

Is the rumored term ‘immunity debt’ real?

Immunity debt claims that lack of exposure to infections in the past few years weakened children’s and adults’ immune systems, causing them to have severe infections. However, it is a known fact that in the absence of infections, the immune system does not lie dormant and weaken. We are constantly exposed to and co-exist with trillions of viruses, bacteria and fungi. They fight it and other cancer cells.

While numbers of RSV infections and influenza are not higher than last year at this time, more adults and children are hospitalized than last year worldwide. With removal of public health measures such as masking, many viruses are spreading widely. Given that we have had a break from these, most of the population is susceptible and exposed again at the same time, attributing to more falling ill. Thus, this rumored term ‘immunity debt’ is not real and not true.

How to take care at home if you have viral infection?

The mainstay of treatment is rest and treat symptomatically. Most people with flu have mild illness and do not need medical care or antiviral drugs. If you get sick with flu symptoms, in most cases, you should stay home and avoid contact with other people except to get medical care, if required.

• Take it easy and get plenty of rest – rest helps speed recovery
• Going to bed early and naps are highly encouraged
• Eat warm food
• Stay hydrated – making sure you’re getting enough fluids (especially water) helps you get better faster and reduces risks of complications. Although you may feel like you don’t want to eat or drink, try taking small sips of water, room temperature juice, or soup regularly throughout the day
• Try to avoid orange and other citrus fruit juices as they may cause nausea and occasionally vomiting
• Do not take anything cold
• Dress warm, especially at night
• Do not expose yourself further to cold weather if ill
• Use Paracetamol for fever
• Use nasal decongestants for runny or blocked nose.

When to consult with a doctor?

• Seek medical attention if there is persistent high-grade fever in children/adults
• Worsening productive cough more than a week
• Associated loose stools or vomiting with dehydration
• Headache, neck stiffness and vomiting
• Altered sensorium
• Trouble breathing
• Noisy breathing
• Compromised immune system

If any of the above conditions are present, one should essentially visit a hospital and seek medical consultation. Do not continue to self-medicate at home!

Are lab tests essential for Viral Infections?

Laboratory confirmation is not necessary for treatment of most viral infections. The approach to testing for seasonal influenza depends upon test availability and how soon the results are needed.

During the winter respiratory virus season, hospitalized patients who are sick or immunocompromised or have findings suggestive of Pneumonia, PCR for influenza, respiratory syncytial virus (RSV), and SARS-CoV-2 are recommended and done worldwide currently. It further helps to start antivirals on time if rightly diagnosed.

Complications of Influenza

• Otitis media or ear pain complicates the course of influenza in 10 to 50 % of children. The typical time of onset for otitis media is three to four days after the onset of influenza symptoms.
• Pneumonia is a major complication of influenza, particularly in high-risk patients.
• Laryngotracheitis or tracheobronchitis – Influenza virus laryngo-tracheitis or trachea-bronchitis may be particularly severe or complicated by bacterial superinfection.
• Secondary bacterial infection – Secondary bacterial coinfection may occur in children and certain elderly adults. Bacterial coinfection should be suspected when severe influenza/influenza-like illness, in children and elderly show clinical deterioration after initial improvement.
• Cardiac complications like myocarditis – rarely.

Influenza vaccination

Influenza viruses change their antigenic characteristics frequently, and their spread depends upon the susceptibility of the population to viruses with novel antigens. Annual influenza vaccination is an important public health measure for preventing influenza infection. Annual vaccination is the best way to increase your immunity to season flu. Several types of influenza vaccine are licensed for use in infants, children, and adults. The vaccine must be taken annually, before the cold season sets in. Egg based vaccines are not to be taken in people with history of egg allergy.