Editor's note: Find the latest COVID-19 news and guidance in Medscape's Coronavirus Resource Center.
The CDC has issued updated guidance for people with underlying medical conditions who are considering getting the coronavirus vaccine.
"Adults of any age with certain underlying medical conditions are at increased risk for severe illness from the virus that causes COVID-19," the CDC said in the guidance posted on Saturday. "mRNA COVID-19 vaccines may be administered to people with underlying medical conditions provided they have not had a severe allergic reaction to any of the ingredients in the vaccine."
Both the Pfizer and Moderna vaccines use mRNA, or messenger RNA.
The CDC guidance had specific information for people with HIV, weakened immune systems, and autoimmune conditions such as Guillain-Barre syndrome and Bell's palsy who are thinking of getting the vaccine.
People with HIV and weakened immune systems "may receive a COVID-19 vaccine. However, they should be aware of the limited safety data," the CDC said.
There's no information available yet about the safety of the vaccines for people with weakened immune systems, the CDC said. People with HIV were included in clinical trials, but "safety data specific to this group are not yet available at this time," the CDC said.
But the new CDC guidance says the FDA "does not consider these to be above the rate expected in the general population. They have not concluded these cases were caused by vaccination. Therefore, persons who have previously had Bell's palsy may receive an mRNA COVID-19 vaccine."
Researchers have determined the vaccines are safe for people with GBS, a rare autoimmune disorder in which the body's immune system attacks nerves just as they leave the spinal cord, the CDC said.
"To date, no cases of Guillain-Barre syndrome (GBS) have been reported following vaccination among participants in the mRNA COVID-19 vaccine clinical trials," the CDC guidance says. "With few exceptions, the independent Advisory Committee on Immunization Practices (ACIP) general best practice guidelines for immunization do not include a history of GBS as a precaution to vaccination with other vaccines."
For months, the CDC and other health authorities have said that people with certain medical conditions are at an increased risk of developing severe cases of COVID-19.
FDA: "FDA Briefing Document, Vaccines and Related Biological Products Advisory Committee Meeting, December 17, 2020."
CNBC: "FDA staff recommends watching for Bell's palsy in Moderna and Pfizer vaccine recipients," "CDC will monitor for Bell's palsy among Pfizer vaccine recipients, but sees no causal relationship."
National Organization for Rare Disorders: "Bell's palsy."
USA Today: "COVID-19 vaccine trials report cases of brief facial paralysis. That's not as scary as it sounds."
Journal of the American Medical Association: "Coronavirus Vaccine FDA Update, posted December 14, 2020."
Reuters: "Fact check: Photo does not show three recipients of Pfizer's COVID-19 vaccine that developed Bell's palsy."