If the vaccine made you achy and slightly flu-ish the day after, it just means you had a greater antibody response. Yay!

According to new research, having such yucky symptoms — it only lasted 1/2 a day with us — is associated with a more robust antibody response.

But that does not mean that if all you had was a sore arm that the vaccine isn’t protecting you.

“I don’t want a patient to tell me that, ‘Golly, I didn’t get any reaction, my arm wasn’t sore, I didn’t have fever. The vaccine didn’t work.’ I don’t want that conclusion to be out there,” said Dr. William Schaffner, a professor in the Division of Infectious Diseases at Vanderbilt University Medical Center.

“This is more to reassure people who have had a reaction that that’s their immune system responding, actually in a rather good way, to the vaccine, even though it has caused them some discomfort,” Dr. Schaffner added.