When Edward Jenner pioneered the first ‘vaccine’ to combat smallpox in the 1700s (which was eventually eradicated in 1979), the world of medicine was changed forever; centuries later, the foundation of his findings has led us to develop a number of vaccines against many other diseases. One of these vaccines is the flu vaccine, which is largely talked about during the ‘flu season’.
Vaccines and how they work
“A killed or weakened form of the vaccine is introduced into our bodies which the immune system then intercepts and is able to overcome, because it is not potent. The B lymphocytes of the immune system, which are essentially ‘memory cells’, are able to help combat the disease if you are exposed to them at a later stage,” explains general physician Dr Pallavi K from Chennai.
In ancient India and China, inoculation against certain types of diseases was practiced. In smallpox, for example, people were purposefully exposed to substance from the smallpox pustules to stimulate a mild reaction which would render them protected against the disease if exposed to it on a larger scale.
“Today, we obviously don’t practice this. Viruses are grown in a laboratory, usually in chicken eggs or some other cell culture, and then the antigens (foreign substance which generates immune response) are extracted from them. Then some stabilizing agents are added which helps keep the vaccine intact,” says Dr Pallavi, “There are some particularities about how individual vaccines have to be stored until they are administered, which have to be followed and managed accordingly.”
Flu season starts
The start of the monsoon seasons in the country is also the start of the ‘flu season’. Young children are particularly susceptible to developing the flu. “The flu season runs its own course, and the symptoms are like viral fever. Children below the age of one, and elderly people are particularly at risk of contracting the flu and are also prone to developing complications from it,” explains Dr Udayakumar, a senior consultant paediatrician from Chennai.
“Flu spreads through droplets, so when someone who is ill coughs it can possibly infect another person who is near them. Another way they may spread is through fomites; if a sick person has sneezed into their hands and then touches a door knob, let’s say, then someone else who touches the door knob can potentially pick-up and contract the virus,” he says.
The flu is brought on by a virus, the most common being the influenza B virus.
Viruses naturally undergo what is called a ‘shift,’ every few years, which results in a new strain of the virus being found. “Shifts are normal, and usually aren’t a cause of worry, however, when a ‘drift’ occurs, that’s when we become more concerned,” says Dr Udayakumar. A ‘drift’ in a virus strain refers to a major change in the virus’ strain and usually occurs every 10 to 20 years according to him. “When a drift occurs, we see more complications and there may be higher mortality rates noted due to the virus,” he says.
He also adds that practicing basic hygiene would help prevent epidemics of the flu, “Wash your hands using soap, cover your mouth when coughing or sneezing.”
Influenza vaccine, side effects
At present two types of vaccines are available against the flu, a trivalent vaccine and a quadrivalent vaccine.
“The trivalent vaccine covers three major forms of the flu, influenza B virus (a common flu virus), H1N1 (swine flu), and another form,” adds Dr Udayakumar, “The quadrivalent vaccine covers another strain of the influenza B virus, which is one of the most common strains of the flu.”
The vaccine is available as an injection or a nasal spray, though the spray is not generally preferred due to its low efficacy. It is generally considered safe for most people, “If someone is already suffering from any respiratory illness, it might also not be recommended for them to get vaccinated. Also, people with certain neurological impairments may also be advised against it. Those who are allergic to eggs are also sometimes advised against taking the vaccine, because it has been known to cause some mild reactions. In general though, it is a good way to protect yourself from the flu,” advises Dr Pallavi.
She also adds that minor reactions to any vaccine are common and nothing to worry about, “Sore throat, pain or redness at the site of the injection are often seen in some people, but this is just the body’s normal immune response and is usually not a cause of alarm.”