Why do some people experience side effects after their second Pfizer and Moderna injection? UCSF physician explains

SAN FRANCISCO (KGO) – As more people are eligible to be vaccinated, reports of side effects surface after the second Pfizer and Moderna shots.

Dr. Robert Wachter, chief of medicine at UCSF, says many of these side effects can last for two to three days. Dr. Wachter says side effects are more common after the second shot because the immune response to the second shot is even stronger than the response to the first shot.

Luz Pena: “Isn’t it a bad thing to have side effects?”

Dr. Watchman: “No, it isn’t. The way I think about them is that it’s a sign that it works. What’s a little funky about that of course when you say people say,” Oh, I had no side Effects. Does that mean it doesn’t work? “The answer is, No. These two things turn out to be true. The side effects are a sign that your body is producing an immune response. If you’re not having any side effects, consider yourself lucky,” but the vaccine also seems to work well in people who had no side effects. “

Pleasanton resident Will Anz received his second Pfizer injection on March 24 and experienced side effects several hours after the vaccination.

“I play recreational hockey and I play goalkeeper and I felt like I was playing hockey 4 games in a row. My body hurt like that. From my neck and shoulders to my ankles,” said Anz.

San Jose resident Anastasia is experiencing similar side effects after receiving her second Pfizer injection on Thursday, April 15.

Luz Pena: How are you feeling?

Anastasia: “I feel fine. A little better than yesterday”, adding, “I just had a really hard night. I think I slept for maybe an hour. I tossed and turned because I’m just hurting had all over my body and I still experience that today just by taking Tylenol and cooling it off here and there. “

Dr. Wachter says body aches, mild fever, and chills are a sign that your body is having an immune response.

Luz Pena: “Why is it that women and younger people have more side effects than the elderly?”

Dr. Wachter: “The younger is easier than the women. The answer to women I don’t think I know and I don’t think we know. The answer to older versus younger is that younger people have stronger, more exuberant immune systems. The vaccine. can induce immunogenicity. This means that your immune system reacts a bit and if you have a more powerful immune system, whatever you do when you are younger.

Another side effect is insomnia. “I’ve heard of it. When the system gets going, it can happen,” said Dr. Wachter.

Many pointed out that they felt the side effects of the vaccine 10-12 hours after that second injection.

“It’s basically a code that triggers your body to produce the spike protein. And then your body starts saying ‘oh this is strange, I’ve never seen this before developing antibodies against it’.” That only takes a little time. That whole manufacturing process works, ”said Dr. Wachter.

What is the difference between a normal response to the vaccine and a response to be concerned about? Dr. Wachter says it’s all about the timing. A bad reaction or an allergic reaction occurs within the first 15-20 minutes after vaccination.

“They affect about 1 in 250,000 people and are easy to treat,” said Dr. Wachter.

Dr. Wachter recommends going to your vaccination appointment hydrated and not taking any anti-inflammatory medications before your injection. Only after that if you need it.

“Like Advil or Aleve which are anti-inflammatory drugs. So the idea of ​​taking a drug to reduce your body’s inflammatory system when you actually want your body’s inflammatory system to respond to the vaccine which is a bit unpredictable. generally, the recommendation is not to take any of those medications before the shot. “

Even after two or three days of unease, many who got the second Pfizer or Moderna shot agree on one thing.

“Small, small price to pay compared to actually getting COVID. I would encourage everyone to get vaccinated,” Anz said.