The Flu Virus and Its Vaccine

What is the flu?

Many of us have experienced influenza, commonly referred to as the flu, at least once in our lives. It’s an uncomfortable experience, characterized by high fevers accompanied by uncontrollable shivering, sore muscles, persistent coughs, and sneezing. Your head feels congested, and your nose seems like it produces an endless supply of mucus. Fatigue sets in, leaving you bored and frustrated but too weak to do anything about it.

There isn’t just one influenza virus; rather, there is a whole family of them, each slightly different. They can be categorized into three main types, and interestingly enough, scientists have opted for relatively simple names:

• Type A: Typically associated with the most severe outbreaks, including the infamous Spanish flu of 1918 and the Avian flu in the 2010s.
• Type B: Generally less severe and more commonly affects children than adults.
• Type C: Usually mild and less prevalent than the other types.

How do viruses make you sick?

Viruses like influenza are biological entities that require a host cell to replicate, which is why they need to infect individuals. Influenza viruses carry RNA, a molecule similar in structure to DNA, which contains the instructions necessary for the virus's replication.

The primary goal of these instructions? To create more of the virus itself. Since viruses lack the biological machinery needed for replication, they have evolved to hijack your cells, turning them into factories that produce new virus particles, thereby impairing their normal functions.

Fortunately, a healthy immune system will eventually identify and eliminate these invaders. However, the situation can be dire for very young children, the elderly, or individuals with weakened immune systems due to illness or treatments like chemotherapy.

A quick note on colds

While the flu is caused by the influenza virus family, common colds arise from a different and vast group of over 200 viruses, including rhinoviruses and coronaviruses. Currently, there’s no single vaccine available for the common cold due to this complexity.

Viruses wear coats

You might have heard flu viruses referred to by names like H1N1, which relate to specific structures on the virus's surface.

The virus's RNA is encased in a protective protein coat, surrounded by a lipid envelope. Two key proteins, hemagglutinin (H) and neuraminidase (N), protrude from this coat. Their variations are denoted by numbers, leading to classifications like H1N1, which corresponds to specific types of these proteins.

These proteins play a crucial role in how our immune system recognizes and responds to the virus. Interestingly, many of the uncomfortable symptoms associated with the flu are actually reactions from our immune system fighting off the virus.

Treatments for flu

It would certainly be beneficial to have more effective treatments for the flu and similar viruses. While there are a few antiviral medications available, they are not cures. They can potentially reduce the duration of illness and lower your contagiousness, especially for those at higher risk.

Antibiotics, however, are ineffective against viruses. They target bacteria, which have distinct biological structures. Some individuals may receive antibiotics after a severe case of the flu, primarily to prevent or treat subsequent bacterial infections.

Enter the vaccine

Given that there are no cures beyond what your immune system offers, the best strategies to combat the flu are:

First, avoid contracting the flu. While you can try to steer clear of infected individuals, it’s challenging since many are contagious before showing symptoms, and few of us live in complete isolation.

Second, get vaccinated. Vaccines prepare your immune system to recognize specific strains of the virus. They contain inactive virus particles that help your body learn what to look for, enabling a quicker response if exposed to the actual virus.

After receiving the vaccine, your immune system skips the initial learning phase, allowing it to react more swiftly to any potential infection. If you experience mild symptoms after your vaccination, it's a sign that your body is adapting, and these effects will fade as your immune preparation continues.

Why do I need to get a flu jab every year?

Viruses are constantly evolving. They engage in a biological arms race with our immune systems, leading to frequent changes in the H and N proteins on their surfaces. When they succeed in altering their appearance, your immune system may fail to recognize them, resulting in delayed responses and potential illness.

Some viruses, like those causing tetanus or polio, change slowly, allowing for long-lasting vaccines. However, the influenza virus family is much more dynamic, rapidly generating new strains, which is why multiple flu strains are included in the annual vaccine.

How do they choose?

Each year, the World Health Organization (WHO), along with various governmental and scientific bodies, analyzes influenza patterns globally. There are 142 national influenza centers tasked with tracking circulating strains, assessing their severity, and how effectively past vaccines have performed.

This data is synthesized at five analysis centers, allowing scientists to forecast which flu strains are likely to pose threats in the upcoming season. While this predictive process is becoming increasingly accurate, it is not foolproof, and unexpected variants can occasionally arise.

Once recommendations are made regarding which flu strains to target, the WHO publishes the findings, guiding governments and agencies in vaccine production. If a new strain emerges that requires a vaccine not yet approved, the urgency may lead to expedited production and testing.

What good is the flu vaccine?

Advancements in understanding the influenza virus and its transmission have enabled scientists to make informed predictions about which strains are most concerning. Therefore, those who receive the flu vaccine are likely to avoid the most severe types of the virus.

While mild cases or colds might still occur, vaccination offers protection against a broader array of flu strains. Should you fall ill with the flu, remember that much of your discomfort is due to your immune system's efforts to restore your health.

For personalized health advice, always consult your doctor or a trusted medical professional. Severe reactions to the flu vaccine are rare, but if you have concerns, reach out to your vaccination clinic.

Further information about flu and vaccines can be found at:

• World Health Organization: who.int/influenza
• National Health Service (UK): nhs.uk/conditions/flu
• CDC (USA): cdc.gov/flu
• Public Health England: gov.uk/2019_2020_flu_season (pdf)