JUNEAU, Alaska — Health officials in Alaska have reported that a second health care worker had an adverse reaction to a COVID-19 vaccine.

Bartlett Regional Hospital in Juneau says the two workers showed adverse reactions about 10 minutes after receiving the vaccine and were treated. One received the vaccine Tuesday and will remain in the hospital another night under observation while the other, vaccinated Wednesday, has fully recovered.

U.S. health authorities warned doctors to be on the lookout for rare allergic reactions when they rolled out the first vaccine, made by Pfizer and Germany’s BioNTech. Britain had reported a few similar allergic reactions a week earlier.