Why does your arm hurt after getting a vaccine?

(Wolf) — The Johns Hopkins Bloomberg School of Public Health held an expert's briefing today to discuss the Covid-19 Vaccine.

With more than 50 percent of adult Americans already having their first does many people may wonder why the vaccine hurts your arm and why you may feel sick after receiving it.

"One of the reasons we have specifically arm pain with vaccines is because we are giving these vaccines in an amount of liquid into areas where you have muscle so there is not a lot of space for that liquid to go and as you stretch those muscle fibers that you are injecting the vaccine into that can be painful," Anna Durbin, MD, Professor, Department of International Health, Johns Hopkins Bloomberg School of Public Health explained.

The Johns Hopkins Bloomberg School of Public Health says that how you react to the vaccine does not determine it's effectiveness.

"Everybody is different so we have different immune responses, we have different pain tolerances, we have different reactions to different things. Some people are allergic to bee stings, some people aren't and it's the same with vaccine reactogenicity. We know that different people react differently. We do seem to see more reactogenicity in women and that is thought to be due to their immune response, but I think what is important to note is that the severity of your reactogenicity is not indicative of how well you are going to respond to a vaccine. So if you didn't have a lot of side effects from the vaccine that doesn't mean that you didn't respond to the vaccine. The vaccine likely worked just fine," Durbin explained.