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Influenza is a highly contagious viral infection and the best way to secure yourself from it is through annual vaccination and proper hygiene. If you do come down with the infection, it is still your responsibility to seclude yourself from others to keep them safe.
Types of Flu Viruses
Flu viruses are classified into four groups: (1)
1. Influenza A virus
The two most prevalent forms of influenza A virus that currently affect humans are A (H1N1) and A (H3N2). Since the A(H1N1) virus was responsible for the flu pandemic in 2009, it is often written as A (H1N1)pdm09.
Influenza A viruses are typically carried by several animals, including cats, swine, ducks, horses, whales, chickens, and seals.
2. Influenza B virus
This form of flu virus is restricted to humans alone, unlike influenza A viruses that circulate among animals as well.
Most of the seasonal flu epidemics that hit the United States almost every year, particularly during the winter months, are caused by either the human influenza type A or B.
3. Influenza C virus
Influenza C viruses do not pose a serious public health concern as they rarely cause any major respiratory illness. This subtype of the influenza virus is not very active and generally triggers a very mild form of infection.
4. Influenza D virus
Influenza type D does not target humans and is mostly prevalent among cattle.
Vaccination: Standard Way to Protect Yourself
A flu vaccine works as the primary defense mechanism against the highly contagious flu infection.
The vaccine exposes your body to a weakened version of the flu virus that is incapable of causing any illness or infection. It takes a few weeks for the vaccine to kick in and trigger the production of antibodies, and so you must exercise necessary precautions in this interim period. (2)
CDC guidelines suggest that anyone above the age of 6 months should get vaccinated against the flu. (3)
You need to get a flu shot annually, as the antibodies from the previous shot tend to diminish over the period of a year. Moreover, the virus keeps mutating and you have to get the latest vaccine available to protect yourself from the newest strain of the flu.
Flu vaccinations are categorized into the following types:
1. Standard flu vaccine
The standard flu vaccine contains antigens, which are proteins derived from the surface of the targeted flu virus. These antigens, once introduced into your body, trigger an immune response.
Once the body familiarizes itself with the influenza virus, it gradually becomes adept at warding off any future infection related to that specific strain of virus.
2. Intradermal flu vaccine for adult ages 18–64
Unlike the standard flu vaccine that is injected into the muscle, the intradermal flu shot is injected into the skin.
This type of flu shot can engender the same immune response as the regular flu shot with a smaller amount of antigen. It is for this reason that intradermal flu injections are usually administered with a relatively smaller needle.
3. Trivalent flu vaccine
A trivalent flu shot is designed to compensate for the age-related loss of immunity in older adults who are above the age of 65.
This trivalent vaccine contains a relatively higher dose of antigen than the other types of vaccinations. Hence, it results in a stronger immune response to the virus. (4)
4. Quadrivalent flu vaccine
As the name suggests, the quadrivalent flu shot provides immunity against four strains of flu viruses, of which two are influenza A viruses and the other two are influenza B viruses. This flu shot is approved for anyone 4 years or older, with the exception of pregnant women and those with certain preexisting medical conditions.
Like most flu shots, this vaccine is also injected into the arm muscle, either with a needle or a jet injector. A jet injector is not preferred for anyone below the age of 18 or above the age of 64. A needle injection can be safely used for anyone who is 6 months or older. (5)(6)
5. Recombinant vaccine
The recombinant vaccine is an FDA-approved quadrivalent flu shot that is intended for adults who are 18 years or older. Traditional methods of vaccine production use chicken eggs to cultivate the vaccine virus.
This egg-grown vaccine virus may trigger an adverse response in people with a preexisting allergy to eggs. In such cases, an egg-free alternative may be used to vaccinate these allergic individuals.
6. Cell-based flu vaccine
This alternative form of the vaccine is more effective than egg-based flu vaccines in warding off influenza viruses.
The cell-based candidate vaccine viruses (CVVs) used in this alternative form of vaccine are a closer match to the flu viruses than those used in regular flu shots. Thus, the protective effect of the cell-based flu vaccine may supersede that of traditional egg-based flu vaccines.
7. Nasal flu vaccine
The nasal flu vaccine contains live strains of flu viruses whose strength has been attenuated or weakened. Unlike other flu vaccines that are injected into the body, the nasal vaccine is sprayed into the nose.
These weakened viruses stimulate the immune system upon entering the body but do not cause any infection or disease in healthy individuals.
It is important to note that the nasal flu vaccine is not safe for pregnant women, children below the age of 2, the elderly, or those with preexisting health conditions. Only healthy people in the age bracket of 2 to 49 years of age are recommended for this option.
Side Effects of the Flu Vaccine
The flu vaccine can trigger a few harmless side effects, which may vary depending upon the type of vaccination.
People who get a flu shot usually experience:
- Some degree of swelling, redness, and soreness at the injection site
- A mild fever
Those who opt for the nasal vaccine may experience:
- Soreness in the throat
- A runny nose
Vaccination not only helps prevent the flu infection but also shortens the flu cycle and reduces the severity of its symptoms if the infection does occur. Moreover, early treatment with antivirals and proper home care helps keep your condition under control and leads to a quicker recovery.
Antiviral medications work best when taken within the first 2 days of the infection but they can provide some degree of relief in the later course of the illness as well.