Gregg Schlaman swears by his annual flu shot. For the past 20 years, Schlaman, a 51-year-old aerospace engineering specialist, has received the influenza vaccine in the comfort of his Palo Alto office, where a nurse administers it between coffee and meetings.

"I have noticed that I don't get sick as often as I used to," Schlaman says. "I think it's the best thing you can do to protect yourself during the winter."

To say John Styles disagrees is an understatement.

"I've never gotten the flu shot, and I never will," says Styles, a 39-year-old Oakland computer programmer who says he gets a cold once or twice a year but is otherwise healthy. "I just think there's too much room for error by the pharmaceutical companies. And I prefer to avoid needles when I can."

Why can't we agree on a seemingly simple health precaution? Because, like everything, pricking comes with pros and cons. Despite the Centers for Disease Control and Prevention recommendation that everyone over the age of 6 months get vaccinated against influenza, only 41 percent of adults and 56 percent of children actually receive the flu shot. Why? Opponents say the vaccine is not fool-proof; they still get sick, and sometimes, within a day of receiving it. Plus, it hurts.

Meanwhile, advocates, including experts, argue that even with mild side effects, the vaccine is a critical first step in protecting yourself, loved ones, and the larger population against the nasty disease, especially this year, since the CDC is offering for the first time a quadrivalent vaccine designed to protect against four different flu viruses: Two influenza A viruses (including H1N1) and two influenza B viruses.

Despite the potentially broader protection, efficacy still varies, depending on how well scientists in the spring are able to identify the flu strains that will be circulating during the upcoming season, says Jeffrey Silvers, an infectious disease specialist with Sutter Health's Eden Medical Center in San Leandro.

The nasal mist form of the influenza vaccine at Kaiser Park Shadelands in Walnut Creek, Calif., on Friday, Oct. 11, 2013. (Dan Rosenstrauch/Bay Area News
The nasal mist form of the influenza vaccine at Kaiser Park Shadelands in Walnut Creek, Calif., on Friday, Oct. 11, 2013. (Dan Rosenstrauch/Bay Area News Group) ( DAN ROSENSTRAUCH )

"Last year's match wasn't very good, and a lot of people got sick," he says. "But one year like that doesn't mean you shouldn't get the vaccine." Silvers says the optimal time to get the vaccine is late October or early November, since influenza typically hits the Bay Area in December or January. "Vaccine immunity wanes with time, so you don't want to get it too early," he says.

Even when the government does find correct viral matches, each person responds differently to the vaccine, depending on his or her age, immune system and underlying medical conditions. As Silvers explains, efficacy might be as high as 80 percent in a healthy young adult, but plummets to 50 percent or less in older people or someone fighting cancer, he says. People over 65 are also more likely to face serious complications or even death as a result of the flu.

"How do you protect your 85-year-old grandfather? You get vaccinated. His wife gets vaccinated. So does the caregiver," says Silvers, describing the concept of herd immunity. When contagious diseases are transmitted from individual to individual, chains of infection are likely to be disrupted when large numbers of a population are immune or less susceptible to the disease.

His overall stance on the influenza vaccine? It's not perfect, but it does help.

"Development of vaccines is a complex process," he says. "We measure response based on the body's ability to develop immunity toward the vaccine, but there is no perfect correlation between vaccine-induced immunity and resistance to infection."

Randy Bergen, a Walnut Creek pediatric infectious disease expert, agrees. "Even if it's only 30 percent effective, which some experts believe, when you look at the number of people we vaccinate, that has huge implications for the health of our community."

Still, he says, the vaccine doesn't protect you from all the other wintertime viruses, including the common cold. "It's the safest and most effective way to protect yourself against the flu," he says. "But you still have to wash your hands constantly and stay home when you're sick."

That's enough for Sylvia Solis to be a vaccine believer. The 29-year-old San Jose teacher's assistant spends her days "around a lot of germs" and has received a flu shot every year for a decade.

"I might have a little pain in my arm or some mild aches, but I don't mind," Solis says. "People always tell me, 'You're so lucky you don't get sick,' but I think it's the flu shot."

Sarah Sohm isn't so sure. It's not that Sohm, 28, is anti-vaccine. She just really hates getting shots. And, she doesn't see an immediate need to be vaccinated against influenza. "I don't have children that could get me sick, and I'm not around people I could get sick," she says.

But, every year, around this time, when Sohm calls her grandparents in Palo Alto to set up their next lunch date, her grandmother, Gayle Pena, skips hello and instead declares this into the phone: "Let's get that flu shot."

Last weekend, as they have for the past 10 years, they went to Safeway together and got their matching injections. "She knows I won't go on my own," Sohm says. "And she wants me to be healthy."

  • Standard dose trivalent shots that are manufactured using inactive virus grown in eggs. These are approved for people ages 6 months and older. There are different brands of this type of vaccine, and each is approved for different ages. However, there is a brand that is approved for children as young as 6 months old and up.

  • A standard dose trivalent shot containing virus grown in cell culture, which is approved for people 18 and older.

  • A standard dose trivalent shot that is egg-free, approved for people 18 through 49 years of age.

  • A high-dose trivalent shot, approved for people 65 and older.

  • A standard dose intradermal trivalent shot, which is injected into the skin instead of the muscle and uses a much smaller needle than the regular flu shot, approved for people 18 through 64 years of age.
    2. New, quadrivalent flu vaccine
    This vaccine protects against two influenza A viruses (including H1N1) and two influenza B viruses. It contains a live virus and is in limited supply, so call your doctor or pharmacy to see if they're offering it this year. It is also offered with inactive strains. The following quadrivalent flu vaccines are available:

  • A standard dose quadrivalent shot

  • A standard dose quadrivalent nasal spray, approved for healthy people 2 through 49 years of age.