Why you need a flu shot

vaccine dose flu shots along with syringe
(Photo: Envato Elements)
As brisk fall winds sweep in, so does the annual flu season. The timing of the onslaught can vary, but influenza cases typically start to ramp up in October and peak between December and February. This year there are signs that, after two years of relative quiet, the flu may be about to come raging back. Many protective measures adopted against COVID-19 that also helped keep the flu in check have been loosened: People are traveling more and wearing masks less.اضافة اعلان

The best way to protect yourself and your family against the flu is to be vaccinated. We asked experts to weigh in on the vaccine, its side effects, and more.

The vaccine’s effectiveness
Flu vaccines are updated every year based on what experts learn from previous seasons, influenza patterns in other parts of the world and estimates of how the virus might change. On average, flu vaccines help reduce the number of people who get sick by 40 percent to 60 percent, said Emily Martin, an associate professor of epidemiology at the University of Michigan School of Public Health. That means that the vaccine can help prevent millions of influenza illnesses, as well as thousands of hospitalizations and deaths, each year. According to the Centers for Disease Control and Prevention, the flu causes roughly 9 million to 40 million illnesses and 12,000 to 52,000 deaths annually.

In general, the vaccines tend to work better against illnesses caused by a strain of virus known as influenza B and a subset of influenza A viruses, Martin said. The shots are less effective against another subset of influenza A viruses known as H3N2. The H3N2 viruses mutate much faster and scientists’ predictions for how the vaccine can protect against these changes do not always match, Martin said.

Even if you do get sick after receiving a vaccine, the shot can reduce the severity of illness. “That is really what we want to do: keep people out of hospitals, living normal lives,” said Dr H. Keipp Talbot, an associate professor of medicine at Vanderbilt University Medical Center.

Studies also suggest that the flu vaccine may help reduce community transmission — meaning that vaccinated people may be less likely to transmit the virus to others, even if they are infected.

Timing and length of protection
Immunity against the flu tends to wane. You have higher protection a couple of weeks after receiving the shot, compared with four or five months later, so it is a good idea to schedule your vaccine appointment close to the beginning of flu season, and not too early, Martin said. “I tend to get vaccinated in October so my antibodies are ramped up by the time holiday travel begins,” she said.

It is important to receive the vaccine before cases start to surge. Your body needs at least two weeks after the shot to ramp up its defenses. People who are more susceptible to severe flu — older adults, pregnant women and very young children — should not delay their shots.

Special guidance
People who are 65 or older are at high risk of developing serious complications from the flu, including pneumonia and inflammation of the lungs, that can cause difficulty breathing and lead to hospitalization and the need to be put on a ventilator. An influenza infection can also increase the risk of heart attack and stroke in older adults, said Dr Tara Vijayan, an infectious disease doctor at the David Geffen School of Medicine at UCLA. “As we get older, we have a natural decline in our immune responses,” she said.
Studies also suggest that the flu vaccine may help reduce community transmission — meaning that vaccinated people may be less likely to transmit the virus to others, even if they are infected.
Older people also tend to respond more poorly to vaccination compared with younger adults. That is why the CDC’s Advisory Committee on Immunization Practices updated its recommendation this year for people who are 65 or older to receive one of three flu vaccines specially designed to better activate older immune systems. Some of these vaccines have been around for several years before the recommendation was formalized. One option is the Fluzone High-Dose Quadrivalent vaccine, which contains four times the dose of a standard flu shot. Another option is the Flublok Quadrivalent vaccine, which is created from a small piece of genetic material from the virus. The third option is the Fluad Quadrivalent vaccine, which is manufactured with an adjuvant, a substance that enhances the body’s immune response. Many doctors and pharmacists are proactively offering these options for older adults, but it is a good idea to check when you go for your shot, Martin said.

The CDC and Advisory Committee on Immunization Practices recommend that pregnant women get vaccinated to protect themselves and their fetuses. Just as the body experiences immune decline while it ages, it also tones down its immune responses during pregnancy, Talbot said. The diaphragm, a muscle below the lungs, tends to move to accommodate the growing fetus, changing the way pregnant women breathe and making them more susceptible to respiratory infections.

Postpartum women, even if they are breastfeeding, can receive any flu vaccine approved for their age. But pregnant women should avoid the FluMist nasal spray vaccine, which contains live virus. This is because the virus in the vaccine could theoretically infect the fetus, even though it has been weakened, Talbot said. The vaccines available to pregnant women contain inactivated virus, or just a small piece of the virus that cannot cause infection.

Children become eligible for flu shots at six months old. The first time they receive a flu vaccine, they need two doses, four weeks apart. After that, they can get one flu shot a year, Talbot said. Children older than two have the option of getting the FluMist nasal vaccine.

Potential side effects
All flu vaccines have a good safety record. The side effects tend to be mild and go away in 24 hours to 48 hours, Martin said. You may experience some soreness or slight swelling around the injection site. Other common side effects include a general feeling of malaise, headaches, muscle aches and nausea.

It is a misconception that receiving a vaccine can give you the flu, Vijayan said. The vaccines are designed so that the virus in them is inactivated or changed, and they cannot make you sick.

It takes two weeks to build up protection from the vaccine, so you could catch the flu in that time. You also may develop a slight fever after getting the shot.

“Any time your immune system is revved up, you may feel a little bit tired, you may have some muscle aches, and you may even get a little bit of a fever,” Vijayan said. “Those are normal things to expect. That’s a sign that your immune system is preparing to fight the real deal.”


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