Why You Really, Really Wanna Time Your Flu Shot Right

Raise your hand if you’ve ever felt personally victimized by cold and flu season. I certainly have. Getting any type of sickness is wack, but the flu is an especially dreadful kind of hell. The viral infection influenza attacks your nose, throat, and lungs, and can leave you with a fever, headaches, and chills, Mayo Clinic says. And, although it’s unlikely for most healthy people, between approximately 12,000 to 79,000 people die of the flu each flu season in the U.S., according to the Centers For Disease Control and Prevention. 

It sounds scary, but don’t panic. Luckily there’s a fairly easy way to combat the wrath of the illness. Getting a flu shot. No one likes shots, but they can save you a lot of pain and trouble in the long run. 

It takes roughly two weeks to build up immunity after the flu vaccine, explains Dr. Cynthia Li, M.D. and the author of Brave New Medicine: A Doctor’s Unconventional Path to Healing Her Autoimmune Illness. “So, given that flu season starts toward the end of fall and beginning of winter, it's ideal to get it then,” she says. That’s the general guideline. But there’s a little more to it than that. 

Dr. Nate Favini, chief medical officer at Forward primary care practice, says that suppliers are already starting to ship flu vaccines to pharmacies and clinics around the U.S. now. “There may be some delays this year because the World Health Organization postponed selection of one of the flu strains for the vaccine for about a month back in March, which means that manufacturers have been working with a shorter timeline than usual,” explains Favini. “So far it does seem like they’re shipping vaccine close to their usual timeline, which has the vaccine coming out in mid-August to mid-September.”

Science is mixed on this, Favini explains. “There’s some evidence that getting a flu shot too soon in the season (in August or September, for example) might leave you with waning immunity to flu in January and February,” he says. “This is probably especially true for people over 65 who don’t tend to have as strong of an immune response to vaccines.” This is in line with research on when to get a flu shot published in the American Journal of Preventive Medicine out of the University of Pittsburgh School of Medicine. Their work found that tens of thousands of cases, as well as hundreds of deaths, could likely be avoided if older adults waited to get immunized. 

“On the other hand, getting a shot early is dramatically better than not getting a shot at all,” Favini says. “So while late October is the optimal time to get a flu shot, if you have a chance to do it sooner and might miss it later in the season, just go for it now.”

As long as there is still circulating flu, it’s not too late. Even if you think you’ve already had it, there are multiple strains of Influenza (usually referred to as A and B) that circulate in any given season. “We’ll give the flu shot all the way through the end of the season in February, March, or April based on the CDC guidelines,” Favini explains. “That said, don’t wait – you get the most benefit if you have immunity when the season picks up in November.”

A 2016 study from the Vaccine peer-reviewed journal showed that people who were vaccinated in the morning have a better response to the vaccine. “In the sense that they have higher flu antibody levels a month after getting the shot,” Favini says. “We don’t know if that translates to lower rates of influenza infection, but it’s reasonable to think it might have an impact.”  

So, if you want to optimize your immunity, he says, a shot before 11 a.m. may be worth it. Still, the time you get it during the season is the most crucial component. “Don’t overthink it if you can only make it at the end of the day,” he says. 

There are a few ways to get the flu vaccine, and they are inactivated and activated. The CDC points out that most people don't have problems with the inactivated vaccine, but minor issues can include soreness or redness at the point of injection, hoarseness, itchy eyes, cough, a fever, aches, and fatigue. If more serious problems occur, you should see a doctor. As for the activated, or live, shot, effects are similar, but can vary depending on if it’s given to a kid or an adult.

The CDC says by the end of October. You can think about getting it in the morning, or in the mid-to late days of the month, but, ultimately, just getting it is the most important thing.