If You Feel This When You Lie Down, It May Be a Delayed Vaccine Side Effect

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While the vast majority of side effects from the COVID-19 vaccine are non-serious symptoms like headache or fatigue, there are incredibly rare cases of serious complications such as allergic reactions or blood clots that can develop. This short list grew recently when the Centers for Disease Control and Prevention (CDC) announced that myocarditis and pericarditis were showing up more often—albeit still incredibly rarely—in some patients who had received their doses. But how can you tell if you're one of the few potentially suffering from heart inflammation? According to Scott Gottlieb, MD, former Food and Drug Administration (FDA) commissioner, you may have the delayed side effect if you notice chest pain you go to lie down.

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During an appearance on CBS' Face the Nation on June 13, Gottlieb explained what might tip you off that there's something amiss. "The signs and symptoms of pericarditis typically are a stabbing or a sharp chest pain that's persistent. It's positional. So it hurts more when you lay back," he said.

"Sometimes it hurts when you take a deep breath because the pericardium, the lining of the heart, rubs against the chest wall, and it might be associated with a fever," he added. In most cases, the delay in onset was brief, with heart inflammation developing "within probably the first two or three days, mostly after the second dose."

Besides stabbing chest pains and fever, both pericarditis and myocarditis can also cause shortness of breath in some patients, according to the CDC. Others may also feel palpitations—which is when the heart feels like it's fluttering, racing, or pounding—while suffering from heart inflammation.

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According to the CDC, the number of heart inflammation cases in young adults after receiving their second mRNA COVID shot from Pfizer or Moderna has been higher than expected. As of May 31, there have been 275 cases reported in young adults ages 16 to 24 years old, the CDC said during a presentation for the FDA on June 10. While not that common relative to the 20 million people in that age group who've been vaccinated, the numbers are still much higher than the 10 to 102 cases of heart inflammation the CDC would normally estimate for that demographic.

However, heart inflammation is still exceedingly rare in COVID-19 vaccine recipients: Out of more than 141 million fully vaccinated individuals, there have been a total of 789 reported cases of myocarditis or pericarditis as of May 31, according to the CDC. And out of 475 reported cases of myocarditis or pericarditis in individuals 30 years or younger, 81 percent fully recovered, with only 15 people remaining hospitalized, as per the CDC's report.

When asked if the public should be concerned about the potential side effect, Gottlieb said it was no reason to consider putting off getting their shots. "I don't think people should be nervous about it right now. I don't think it changes the risk-benefit balance for this vaccine," he said.

He added that the heart inflammation reported in some patients could also be the result of other viruses that young people catch once they return to public outings after receiving their shots. "It's not clear that there's a causal relationship between the vaccine and these cases. If there is, it's probably an inflammatory response from the vaccine," he suggested.

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