WILKES-BARRE, LUZERNE COUNTY (WBRE/WYOU-TV) — Johnson & Johnson is still waiting for emergency use authorization for its one-dose COVID-19 vaccine. The other two vaccines that are currently available, require two shots.

You may wonder why the second shot is necessary and what happens after you get it.

Geisinger Centerpoint resumed distributing the vaccine, on Tuesday, to qualifying individuals, after the storm forced shots on Monday to be postponed.

Eyewitness News spoke with a Geisinger infectious diseases specialist about everything you need to know concerning the two shots.

It’s been three weeks since Geisinger began administering the Moderna COVID vaccine to members of Pennsylvania’s COVID-19 Vaccination Phase 1A group. Next week, these individuals will be ready for their second shot. Why a double dose?

“Some vaccines do require more than one dose, right. Think about things like polio vaccine or measles, mumps, rubella vaccine. They often times require a couple doses to really kind of boost the immune system to sufficient levels,” explained Dr. Stan Martin, Director of Infectious Diseases at Geisinger.

Both Moderna and Pfizer developed their vaccines as a two-shot series even though that first shot provides benefits.

“And usually after ten or 12 days after that first shot, you start to see some protection creep in from that first vaccine. Now, it may not be super high protection and it may not be long-lived protection,” Dr. Martin said.

Some estimates indicate more than 50 percent protection from the first shot, which most people have tolerated quite well. Dr. Martin says that might not be the case when you get the second dose.

“Their immune system is revving up as a response to the vaccine and when that happens, you typically don’t feel well. Right? You may have body aches, you may feel very tired, you may have headaches, you may even have fevers.”

Dr. Martin says the symptoms are not typically severe and should resolve themselves in 24 to 48 hours. It’s something employers may want to consider if they are making provisions for their staff to get that second shot.

“And so, I think preparing for that makes sense.”

The Moderna second shot is recommended four weeks after the first. The Pfizer booster shot can be given three weeks later.

The state is still in the phase 1A vaccine group. The state Department of Health has details on its tiered vaccine distribution on its website.