COVID-19 vaccine: What do warnings of allergic reactions mean? Yahoo News Explains

The National Health Service in the U.K. has issued a warning to people with a history of severe allergic responses after two health care workers experienced “anaphylactoid reactions” to the Pfizer COVID-19 vaccine. Yahoo News Medical Contributor Dr. Uché Blackstock explains what this means for the vaccine rollout in the U.S. — and why it’s not time to start panicking.

Video transcript

UCHE BLACKSTOCK: Yesterday, the UK rolled out the vaccine by Pfizer, and thousands of people were vaccinated, mostly health care workers and people over the age of 80. And it turns out that two of the health care workers who received the vaccine had severe anaphylactoid reactions to the vaccine.

An anaphylactoid reaction is a reaction that's like anaphylaxis. So anaphylaxis is a very severe allergic reaction that affects many different organ systems. So your blood pressure goes down. You could lose consciousness. Your heart rate goes quickly.

But they're calling it anaphylactoid, which means that it may not necessarily be a true allergic reaction. It just kind of looks like an allergic reaction, which means that they need to do more research and observation to figure out exactly what happened.

So now National Health Service is saying that anyone with a history of severe allergic reactions that required epinephrine, otherwise known as adrenaline, should not take the vaccine.

And I actually feel like we really don't have enough information yet. There are only two health care workers out of thousands of people who received the shot yesterday. We don't know if their reactions were just coincidence or actually caused by the vaccine.

We also know that the vaccine has been in clinical trials and has been given to tens of thousands of patients, and we had not actually seen in some of the data that's been revealed so far that any of those patients have had severe anaphylaxis or anaphylactoid reactions.

I would also say that the vaccine-- although it was developed in a very short period of time, the reason why it was done so is because typically these phases are done consecutively, as opposed to in parallel. We actually had unprecedented opportunity with federal funds and dollars that were put towards vaccine development.

And so I don't think that this is any cause to worry about the quality of the vaccine or to worry about the data that we have on it so far. I think what we have in terms of the briefing report that came out from the FDA yesterday was incredibly reassuring.

This vaccine by Pfizer is one of the first that's approved in the UK and will likely be approved here in the US. Moderna will likely be approved before the end of the year, and then AstraZeneca and Johnson & Johnson are still in phase 3 and will likely be approved within a few months.

If it turns out that they are having true allergic reactions to this vaccine, there will definitely be other options for vaccines for people to have in the future.