As experimental coronavirus vaccines inch toward approval in the United States, Homeland Security investigators are warning pandemic-weary Americans of fraudulent COVID-19 treatments and preventions sold online. (November 27)

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Vaccines are on the horizon in the U.S., and distribution could potentially begin by mid-December.

Two companies – Pfizer and Moderna – have already applied for emergency use authorization from the U.S. Food and Drug Administration for their two-shot vaccine candidates, and more companies are expected to apply in the coming months. 

On Wednesday, the United Kingdom became the first western country to approve widespread use of a COVID-19 vaccine developed by drug companies Pfizer and BioNTech, making it one of the first countries to begin vaccinating.

As vaccines are being produced in record time, what do we know about these shots?What are the side effects? Will you be immune? And will you have to take the vaccine once or every year?

We know you have questions, and we’re here to help. Ask us your vaccine questions through this online form, and we’ll speak with public health experts to answer them below.

Here’s what we know:

Is there a vaccine for the coronavirus? When will the COVID-19 vaccine be out?

There were more than 200 vaccine candidates under development as of last month, with 48 in clinical trials, according to the World Health Organization. Drug companies Pfizer, Moderna and AstraZeneca have the leading vaccine candidates. Pfizer is collaborating with German company BioNTech, and AstraZeneca is collaborating with Oxford University.

There are no authorized COVID-19 vaccines in the U.S. yet, but preparations for distribution are ramping up. Under FDA rules, a vaccine cannot be shipped to administration sites until it has been either licensed or authorized. Operation Warp Speed, the White House-led initiative to develop and distribute vaccines, plans to begin the first vaccine deliveries within 24 hours of FDA authorization.

The FDA is expected to authorize Pfizer’s vaccine by mid-December. Charter flights bringing Pfizer’s COVID-19 vaccine to the United States from Belgium began Friday, the start of what the Federal Aviation Administration calls the first “mass air shipment” of a coronavirus vaccine.

Biotech company Moderna applied Monday for an emergency-use authorization from the FDA. Meanwhile, AstraZeneca/Oxford faced scrutiny over interim results from trials in the U.K. and Brazil, released last week, showing 60% effectiveness when its vaccine was given in two equal doses and 90% among a much smaller group that accidentally received a half-dose the first time.

Moderna said recently it will have 20 million doses available in the U.S. by the end of this calendar year and another 500 million to 1 billion next year. Pfizer has said it will have as much as 50 million doses of its vaccine manufactured by the end of this year, and another 1.3 billion next year. Both companies have agreed to provide Americans with 100 million doses apiece, already funded through federal support of manufacturing and distribution.

What we know: There are now three promising COVID vaccine candidates

What are the side effects of the coronavirus vaccine? Are there long-term effects?

Most people who get a COVID-19 vaccine will endure side effects, particularly after a second dose. All three candidate vaccines reported mild or moderate side effects, mostly pain at the injection site, fatigue, and aching muscles and joints for a day or two.

“A sore arm and feeling crummy for a day or two is a lot better than COVID,” said Dr. William Schaffner, professor of health policy and of preventive medicine at the Vanderbilt University School of Medicine.

If someone is going to have a bad reaction to a vaccine, it is likely to occur in the first six weeks after vaccination, according to medical experts. But experts still don’t know the long-term effects of the vaccines and won’t know until after the trials are completed and researchers monitor participants in the real world for years after.

In Dr. Fauci’s words: Why Americans shouldn’t fear a COVID-19 vaccine authorized by the FDA

Can I choose the vaccine I want?

The vaccine you’re offered will depend on how close you live to a medical center equipped with medical-grade ultracold freezers, said Jeylan Mammadova, health care analyst for investment research firm Third Bridge.

The Pfizer vaccine must be kept super-cold – at the temperature of dry ice – making it harder for most pharmacies and doctor’s offices to accommodate it. The vaccine can be stored for up to five days at normal freezer temperatures. It is shipped in boxes that contain 975 doses, so a vaccine administration site would have to be able to use up all those doses within five days, which will likely need to be at a larger medical center.

As for Moderna’s vaccine, Schaffner said that potential vaccine may be more widely distributed as it can be refrigerated for up to a month before being used. Similarly, the AstraZeneca/Oxford vaccine can be kept refrigerated throughout, which should make it easier to deliver to areas that do not have easy access to freezers.

“Moderna’s vaccine will be more available in suburban and rural areas where it’s harder to get access to ultracold storage and where the ability to use 975 doses of vaccine within five days is more limited,” Mammadova said. 

Can you get one dose from one vaccine and another from a different vaccine?

Most of the vaccines at this stage require two doses to become maximally effective. The Pfizer/BioNTech shots are given 21 days apart, Moderna’s are given 28 days apart, and AstraZeneca/Oxford’s about a month apart. 

Since the vaccines differ in composition, storage and time between the two doses, experts say people must take the same vaccine for both doses. 

“You have to get the same vaccine the second time,” Schaffner said. “We will have no information on what we call ‘mixing and matching.'”

It’s possible that future research will show that getting a similar type of vaccine – one within the same “class” – would be effective, but “no one knows” at this point, said Dr. Greg Poland, director of the Mayo Clinic’s Vaccine Research Group. “There are zero studies looking at vaccine interchangeability at this point.”

State registries, called Immunization Information Systems, will make it easy for health care providers to keep track of which patient gets a particular vaccine. The registry will contain information on the patient, which vaccine they received and when they received it. This system gives patients the flexibility to receive their doses at different health care providers as long as it’s in the same state. 

For the vaccines that require two shots, what happens if the second shot is delayed due to lack of availability?

Current research shows that, for the vaccines that require two shots, people should receive both for maximum benefit, Poland said. 

However, receiving the first injection alone would still provide some benefit, he said.

As with other vaccines – like the measles, mumps and rubella vaccine – experts say it’s never too late to get the second dose even if it’s after their scheduled vaccination appointment. 

Patients won’t have to retake their first dose, so physicians urge them to call their health care provider to reschedule a time for their second dose as soon as it becomes available.

If you already had COVID-19, should you still get vaccinated?

Yes. People who have had COVID-19 “may be advised” to get the vaccine, “due to the severe health risks associated with COVID-19 and the fact that re-infection with COVID-19 is possible,” according to the CDC.

While serological testing can determine if a person has virus-specific antibodies that can protect against SARS-CoV-2, the virus that causes the disease COVID-19, experts say it’s still unknown how long those antibodies will be present in the body after infection. 

“We don’t know for how long the protection will last after you’ve recovered,” Schaffner said. “It’s always good to get vaccinated because it provides the best protection.” He said there will be no serological tests to screen for prior COVID-19 infection at the vaccination sites.

There’s no evidence that a vaccine poses any risk to people who have previously had COVID-19. “There’s no contrary indication to getting the vaccine if you’ve had COVID,” Poland said.

Medical experts urged patients not to go into the doctor’s office for their scheduled vaccination if they’re presenting symptoms of COVID-19. That would pose risk of transmission, as well as confound the cause of any potential side effects, Poland said.

“There’s always the proviso when somebody comes for a vaccine that, if they have a fever or active infection, we would generally delay it,” he said.

Once you get vaccinated, can you still get sick? Can you still transmit the virus to other people?

Yes, it is possible that you could still get sick or transmit the virus to someone else, even after having received the vaccine, according to experts. “The vaccines are 90% effective. That means that there’s a small chance you could encounter the virus and still get sick,” Schaffner said.

For example, data from Moderna showed that of 196 people in the clinical trial who caught COVID-19, 11 had received the vaccine. But none of those 11 participants had severe disease, suggesting that the vaccine prevented severe disease.

It’s also possible to get sick if you don’t give the vaccine enough time to provide protection. It typically takes “a few weeks” for the body to build immunity after vaccination, according to the CDC. So it’s possible that someone could be infected with the virus that causes COVID-19 just before or just after vaccination and get sick.

A third possibility? The vaccine could prevent you from getting the disease, but not from transmitting the virus to someone else. “To prevent asymptomatic infection and transmission, you need what’s called sterilizing immunity,” Poland said. “To prevent severe disease and it’s complications, you need only to develop neutralizing antibodies. It doesn’t have to be sterilizing.”

It’s not yet clear if the COVID-19 vaccines can produce sterilizing immunity.

How long will COVID-19 vaccine last? Will this become an annual shot like the flu shot? What if the virus mutates?

While the vaccines have proven protective against the virus, there’s no data that shows how long that protection can last, Schaffner said. “That protection may wane over time, and you may be susceptible again,” he said.

A vaccine could trigger an immune response that lasts longer in some people than in others, Poland said. 

It’s possible that the virus could mutate.

“How often? No one knows. We haven’t actually seen a mutation yet that escapes vaccine-induced immunity, but there are no theoretical or observable reasons why that couldn’t happen,” Poland said. “The more times we passage this virus through humans, mink, other animals, the more likely that this is eventually going to happen.”

Where are the Pfizer, Moderna vaccines made?

Pfizer has two plants making its COVID-19 vaccine, one in Kalamazoo, Michigan, and one in Puurs, Belgium. The company has a distribution site in Pleasant Prairie, Wisconsin, where its vaccine is being stored. There may also be other sites around the nation where the vaccine will be stored prior to authorization.

Moderna has started producing vaccine at its plant in Norwood, Massachusetts, and it will ramp up production in the next month with help from contract manufacturer Lonza Biologics, which has a facility in Portsmouth, New Hampshire. 

Want more information about how vaccines are authorized, approved and monitored? Food and Drug Administration Commissioner Stephen Hahn answers questions here.

Contributing: Elizabeth Weise, Karen Weintraub, USA TODAY


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