Flu is not unique to a few regions or specific age groups. Everyone can get infected, while the consequences depend on various factors, often unpredictable. In a nutshell, we can break down influenza into four categories based on the virus subtypes. Influenza type A is far more threatening than the rest of the crew due to high contagion. On top of that, influenza type A can be transmitted from wild birds and other animal species, which explains a few flu pandemics in the past. Everyone, ranging from kids to youngsters to the elderly, should take heed of the dangers of influenza. The optimal approach is an influenza vaccine which embraces a variety of options. That said, the extent of influenza type A victims is broader than human beings and goes as far as to involve chickens, horses, pigs, and even cats. Read on to learn about influenza type A, its symptoms, and the influenza vaccine.
Variants of Type A Influenza
Influenza type A virus is an RNA virus and a member of the virus family Orthomyxoviridae. RNA viruses usually contain ribonucleic acid and are renowned for having a high mutation rate. Influenza type A virus shares this trait with many other human diseases, such as Covid-19, hepatitis E & C, Ebola virus disease, and the common cold. There are a bunch of subtypes for influenza A viruses determined according to the types of two proteins on the viral envelope — the outermost layer of the virus. These proteins are called hemagglutinin and neuraminidase, depicted with H and N, respectively. Until now, we know of 11 types of neuraminidase and 18 types of hemagglutinin (you could do the math for yourself, but not every possible combination exists). For instance, the H3n2 or H5N1 are known subtypes of influenza type A. Nevertheless, this is not the only method to label them. One way to name type A influenza viruses is based on their typical hosts, like human flu or avian influenza. In addition, we can recognize influenza type A variants in accordance with their subtype or how deadly they are.
Though structurally similar to influenza B, C, and D, influenza A viruses can infect a broad spectrum of animals. That explains the diversity of influenza type A, like human flu, bird flu, bat flu, swine flu, canine influenza, and equine influenza. Our focus, however, is mostly centered on human influenza. H1N1, H3N2, and H1N2 are the most spread subtypes of influenza A that cause infection in human beings and the first two subtypes are among the targets of influenza vaccines. That being said, it is also possible for us to get infected by other subtypes that have to do with other animals. Though rare, these cases often result in more extreme situations.
Though the influenza vaccine has effectively curtailed the occurrence of flu epidemics at intervals, a new flu strain can ignite an expansive outbreak. That is due to the unfamiliarity of the immune system to the newly emerged virus. There have been six influenza pandemics over the past century and a half. The chief reason for these epidemics is what we call antigenic shift, which is when the influenza virus changes drastically, and a novel combination of hemagglutinin and neuraminidase come to exist. Consequently, the newly made strain begins to easily circulate among people and possibly other animals since there is little immunity against it. Amongst these pandemics, the Spanish flu was the most severe one, which took place in 1918. The cause of this epidemic was an H1N1 virus, which involved up to one-third of the world’s population and brought up horrible death rates, at least 50 million people worldwide. The same H1N1 strain caused the swine flu pandemic back in 2009-2010. What’s more, the Asian flu was another disastrous worldwide pandemic caused by the H2N2 avian influenza virus in 1957, which wound up in the death of 1.4 million. Anyhow, not all epidemics are so brutal, as there have been many other outbreaks of shorter scope and less severity too.
Bird flu, or avian influenza, is one of several variants of influenza type A, with more frequency among humans. Wild aquatic birds, like shorebirds and gulls, are the prominent hosts for bird flu viruses. However, the high spread rates of these viruses make them quite prevalent among domestic poultry and other animal species. Taken from touching the bird to coming to touch with their droppings, any close contact with a dead or alive infected bird can be a way of transmission. Nonetheless, cases of human affliction with bird flu viruses are rare, despite a few strains with troublesome histories. For example, the avian influenza A(H5N1) virus became a serious concern around 1997 as a poultry outbreak sprang up and resulted in cases of human death. As of now, H5N1 has caused an overall of 860 human infections from 2003 to 2022 in 19 countries with a fatality rate of 53%, and it still goes on. Besides, the H7N9 virus is another dangerous influenza A virus that has infected over 1,500 people by now at a case fatality rate of 39%.
Symptoms and Prevention
Besides the direct transmission of avian influenza from infected birds, close contact with an intermediate host can also be a possible way of transmission. Therefore, it is vital to be familiar with the bird flu symptoms. Some of the most common symptoms are headache, aching muscles, a high temperature or feeling so, coughing or shortness of breath, and diarrhea. The available vaccines are best to protect against two influenza A and two influenza B viruses, and any vaccine for protecting humans against avian flu is missing. That said, some healthcare considerations regarding poultry can be beneficial, such as washing hands before and after food preparation, eating fully cooked meat, and avoiding close contact with birds.
Type A Influenza Symptoms and Treatments
The most common symptoms of influenza A include chills, fever, muscle aches, sneezing, cough, runny or stuffy nose, and conjunctivitis (an eye condition with redness and swelling). In extreme cases, influenza A viruses can affect the lungs, leading to breathing difficulty and possibly pneumonia. Some factors determine the longevity of the symptoms, as well as their severity and lasting complications. We expect the flu symptoms to appear within the first three days and abate in a week. That being said, it can lead to deadly complications that might remain with the patient for long, such as multi-organ failure, myocarditis (inflammation of the heart), and encephalitis (inflammation of the brain). That being said, flu infections in the past can provide partial immunity, which has a hand in a more facile convalescence. On top of that, a healthy lifestyle with room for regular workouts and a nutritious diet can be of benefit. If infected, you can treat the flu with the help of antiviral drugs. The CDC-recommended/FDA-approved antivirals go hand in hand with the influenza vaccine in keeping wayward flu viruses at bay. These medications are zanamivir (Relenza®), baloxavir marboxil (Xofluza®), oseltamivir phosphate (Tamiflu® plus other generic versions), and peramivir (Rapivab®).
In brief, inactivated influenza vaccine (IIV) and live attenuated influenza vaccine (LAIV, aka the nasal spray) are two types of flu vaccines available. The former type enjoys a number of options under different brand names, some of which include a recombinant flu shot, standard-dose flu shots, an adjuvanted flu shot, and a high-dose flu shot. They might be egg-or-cell-based and vary in age range, administration routes, and cost. Nevertheless, they offer similar safety and protect against two influenza A and two influenza B viruses. Moreover, biosimilar vaccines are progressively gathering attention, so as far as to encourage many pharma companies to invest more. Biosimilars are especially advantageous in developing countries with low-grade access to quality medications. In the wake of dumbfounding technologies, biosimilars have made it possible to enjoy similar functions of a biologic vaccine or drug at a lower cost. For example, Opal Biopharma (OBP) is one of the pioneering manufacturers of biosimilar products—including the biosimilar influenza vaccine. With a top-level R&D center and high-tech facilities, Opal Biopharma is taking worthwhile steps toward further research and improvements in this field.
As the most typical type of flu, influenza A holds the #1 rank among the other influenza types in terms of contagion, severity, and subtypes. Adjacent to humans, different animal species, like birds and pigs, can also get infected with influenza A and experience pandemics. Although symptoms like fever, chills, headache and muscle aches, cough, and sneezing are the common grounds of flu and cold, more consideration is required on the side of influenza. We can cope with influenza type A despite the adverse consequence it may impose on us. The influenza vaccine ensures trustful immunity against both influenza A and B, the initiators of seasonal flu. This is of much greater importance for kids and people 65 years and above, along with those dealing with medical conditions like diabetes, asthma, and heart disease.