By Dr. Max Gomez

NEW YORK (CBSNewYork) – As COVID vaccinations ramp up with more people becoming eligible, there are also more questions about the vaccines.

Can you still get COVID if you’ve had just one dose, and what if you mix Pfizer and Moderna vaccines?

CBS2’s Dr. Max Gomez has the answers.

Our first question comes from a viewer named Jon, who asks “Can you mix and match vaccines? One shot from Moderna and the second from Pfizer, or vice versa?

Unfortunately, the answer is we don’t really know, because those combinations have never been tested – at least not yet.

In theory, mixing and matching the two vaccines could work because they contain the same coronavirus genetic sequence to stimulate immunity. The only difference between the Moderna and Pfizer shots is the tiny lipid nanoparticle that surrounds the fragile mRNA gene.


But right now, with vaccine in short supply, it’s unlikely that anyone will be able to get one of each vaccine. Just get whichever you can because the site that gives you your first dose should prioritize you for your booster second dose.

Our second question is a little easier because there’s some data behind it. Cathy asks “Can you still get COVID after the first vaccine dose?

The short answer is yes, but not as often or as easily as before that first dose. The Pfizer clinical trials suggested about 50% protection after the first dose. A new Israeli study finds a drop in new cases after the first dose. That’s something, but not perfect, and it takes a few weeks after that first shot develop much immunity.

So yes, you can still get COVID until you’ve had both doses, so you must keep wearing a mask.


There is one bit of good news in all this. The CDC says that flu activity remains lower than usual for this time of year. That’s probably due to people wearing masks, social distancing and washing their hands often. So keep it up – we don’t want a twindemic.

Do you have a COVID vaccine question for Dr. Max? Let us know!


Dr. Max Gomez