Your questions about the Pfizer COVID-19 vaccine answered

On December 11, the FDA issued its first emergency use authorization (EAU) for a COVID-19 vaccine, co-developed by pharma giant Pfizer and German biotech firm BioNTech.

While everyone knows that the approval of a COVID-19 vaccine could help end the pandemic, there’s also a lot people don’t know about the vaccine itself.

To help, here are answers to your frequently asked questions about the COVID-19 vaccine.

How Does the COVID-19 Vaccine Work?

The vaccine uses a small piece of the coronavirus’s genetic material to trigger the immune system to produce antibodies against the virus.

Those antibodies will help the body fight off the coronavirus if it infects the person later.

How Effective Is It?

A two-dose regimen of Pfizer’s COVID-19 vaccine was found to be 95% effective at preventing a coronavirus infection in a study involving more than 44,000 participants.

Crucially, the vaccine appeared to be more than 94% effective in trial participants over the age of 65 — a group particularly susceptible to severe cases of COVID-19 — and people at high risk from comorbidities.

A striking chart from the FDA report on the vaccine shows just how effective it is, comparing the number of COVID-19 cases in the placebo group (red line) vs. the vaccine group (blue line) over time.

How Long Does It Last?

We don’t know for sure since the disease is so new — we can’t say if protection will last five years, for example, because the virus hasn’t even been around that long.

There is a chance people will need to get booster shots, but only time will tell.

What Are the COVID-19 Vaccine’s Side Effects?

The most commonly reported side effects among trial participants were “pain at the injection site, tiredness, headache, muscle pain, chills, joint pain, and fever,” according to the FDA.

Experts say these are normal reactions that show your immune system is responding to the vaccine.

Minor side effects, like pain at the injection site, were common and generally faded after a couple days; side effects were more likely after the second vaccine dose than the first (likely because the immune system is now primed to recognize it and reacts faster).

Older people were less likely to report side effects than younger people.

Is the Vaccine Safe?

Reports of serious adverse reactions during the trials were rare, occurring in just 0.63% of participants given the vaccine, compared to 0.51% of people in the placebo group.

The FDA determined that most of the reactions were unrelated to the vaccine, which is why the placebo group saw them as well.

By the end of its analysis of Pfizer’s COVID-19 vaccine, the agency found “no specific safety concerns identified that would preclude issuance of an EUA.”

How Many Doses Are There?

Pfizer is expected to deliver enough doses for 20 million Americans in 2020 and 40 million more in early 2021.

That’s well short of the 300 million Americans who need a vaccine, but other coronavirus vaccines are already near approval, so the U.S. likely won’t need to rely solely on Pfizer to immunize its population.

Even coronavirus survivors should get vaccinated once doses are available.

Who Can Get the COVID-19 Vaccine and When?

A CDC committee came up with a plan for the order of the roll out, recommending that medical workers and nursing home residents get the first doses — distributing to those people has already begun.

While it is up to individual states to make the final decision on who gets the vaccine first, most will likely adhere to the CDC’s guidance.

Who Can’t Get the Vaccine?

People younger than 15 aren’t allowed to get Pfizer’s COVID-19 vaccine yet, since they were not included in the initial studies. Anyone who’s had a severe allergic reaction to any of the vaccine’s ingredients shouldn’t get it, according to the CDC.

Several other groups should “proceed with caution” before getting the vaccine, talking with their doctors about potential risks. Those include people with compromised immune systems, like HIV, and people who’ve had severe allergic reactions to vaccines or injectable therapies in the past.

Pregnant people, meanwhile, should be told by their doctors that the vaccine hasn’t been tested in expectant mothers yet (though animal studies have revealed nothing to indicate the vaccine might harm developing fetuses).

How Much Does It Cost?

One of the big questions about the COVID-19 vaccine is its cost. Good news, there: the government is footing the bill for the vaccine itself.

However, the person who vaccinates you can charge for the service. Your insurance will probably cover that fee, and if you’re uninsured, there are federal relief programs that will pay it.

Pfizer’s COVID-19 vaccine was 95% effective at preventing a coronavirus infection.

How Fast Does It Work?

Pfizer’s reported 95% efficacy starts from seven days after the second dose.

Trial participants did start building up immunity to the virus between the first and second shot, but we don’t know exactly how effective the vaccine is at those earlier stages.

Can I Act Like the Pandemic Is Over Once I’m Vaccinated?

Not quite. Pfizer did not test its vaccine’s ability to prevent asymptomatic COVID-19 infections, and people without symptoms can spread the coronavirus.

That means you’ll still need to be careful after receiving the vaccine to avoid potentially carrying it to others — at least until the pandemic really is over or new studies show this vaccine prevents asymptomatic spread.

Should I Get the Vaccine If I Had COVID-19?

Yes. While we don’t know for sure which is the better type of immunity (the kind you get from surviving COVID-19 or the kind you get from a vaccine), experts say the immunity provided by the vaccine is more reliable.

“We know the dose that is being administered, and we know that that dose is effective at eliciting an immune response,” Jennifer Gommerman, an immunologist at the University of Toronto, told the New York Times. “So that becomes a variable that’s taken off the table when you get the vaccine.”

So, if and when the doses are available, even coronavirus survivors should get vaccinated.

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