The Corner

Politics & Policy

The First Dose and the Second Dose of the Coronavirus Vaccines Are the Same Stuff

A point that really could have been clearer in much of the coverage of the vaccinations in the past two months: the first dose and the second dose of the Pfizer and Moderna vaccines are the same thing. Many people’s bodies react differently to the second shot, but the substance is identical.

“What is injected is exactly the same,” said Dr. Anna Wald.

Dr. Wald said while there’s no difference between the first and second doses, how people react to the second dose is often different from how they reacted to the first.

“How people respond is often not the same because once you’ve had one injection, your immune system is regulated and all excited to see this molecule and when it sees those molecules again it can produce a stronger response,” she said. “So, a lot of people report that with the second shot they’re more likely to have flu like illness or a very sore arm.”

That makes this report of a snafu in Pennsylvania a little odd:

Yet on Wednesday, Acting Health Secretary Alison Beam announced providers since early January have been giving out second doses of the Moderna vaccine as first doses, characterizing it as a significant mistake. More than 100,000 people could be affected, Beam said.

Because of the error, Beam said up to 60,000 people could have to reschedule appointments, and up to 55,000 others might be delayed in getting their initial doses.

While not fully reconciling the apparent conflict in guidance, Beam laid out the details while also saying the state can adjust so that everyone gets their second dose within an acceptable time frame. There is no medical difference between the first and second doses, so the situation should provide no immediate health danger, she noted.

Beam refused to assign blame, although she suggested the state health department is at least partly responsible.

“What we are working on is making sure our department, our communication, our transparency, our end of the bargain is improved upon,” Beam said.

In other words, “first dose” and “second dose” are entirely a matter of what’s written on the label. We wouldn’t want the distribution of “second dose” shots to disrupt people getting their actual second serving of the vaccine about four weeks later. But every “second dose” shot is completely safe and usable for a person who isn’t vaccinated yet. The state and vaccine administrators are worried about running out of doses set aside to be second shots, so that people who got the first one don’t get their shot in that 28-to-42-day window (and doctors strongly encourage people to get their shot in the earlier end of that window).

The state agency accidentally did what some health experts want state governments to do deliberately — use the doses set aside for the second dose now to maximize the number of people with at least some vaccine protection, and count on incoming supplies to be there in the coming weeks.

The Pennsylvania Department of Health plans to use some of its stockpile inventory and to extend the time between first and second doses for some patients.


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