(WHTM) – The Centers for Disease Control and Prevention is recommending a new first-approved vaccine to protect infants from the leading cause of hospitalizations.

“From a pediatric standpoint, we’re very relieved that there’s a possibility for us to protect that incredibly vulnerable population of ours and to do so even before they’re born is even more exciting,” said Dr. Joan Thode of Penn Medicine Lancaster General Health’s Roseville Pediatrics.

Respiratory Syncytial Virus peaks in the fall and winter months attacking the lungs.

It can cause mild, cold-like symptoms. Most people recover in 1 to 2 weeks, but it can become serious for adults 60 years and older, especially infants.

“In general, the first two months of a baby’s life or a newborn’s life are the most vulnerable from an immune system standpoint,” said Dr. Thode.

But now doctors say newborns will be able to fight back as the U.S. Food and Drug Administration approved, Abrysvo made by Pfizer, a vaccine for pregnant women.

“Those antibodies will cross the placenta into the baby’s bloodstream,” said Dr. Thode.

So, if you’re pregnant, here’s when experts say you should get the vaccine.

“I believe they try to time it during week 30 to the 36 of the pregnancy. And they generally try to time it so we can get it during RSV season. So, for example, if you are delivering in June when there’s very little RSV around, your doctor may not recommend the vaccine for the mother. If you’re delivering during September, October, November, or December, they’re very likely to recommend,” said UPMC Infectious Disease Specialist, Dr. John Goldman.

Health experts say side effects can include pain at the injection site, headache, muscle pain, and nausea.

If you’re skeptical of getting the vaccine.

“In America, we have an incredible series of checks and balances for any of these, you know, whether it’s a vaccine or a medication to come to actually be accessible to the general population…As a doctor and as a parent, I would, if I were expecting, I would wholeheartedly and happily get the RSV vaccine to protect my child ahead of time,” said Dr. Thode.