Since March, public health experts have said that a vaccine is our best hope for ending the coronavirus pandemic. As a result, companies have broken speed records to develop a COVID-19 vaccine, such that 2020 may end with a few different candidates starting to roll out. The vaccine made by drug company Pfizer was the first to receive the FDA's emergency use authorization, and the first vaccinations have begun across the U.S. for healthcare workers. The vaccine by pharmaceutical company Moderna was given emergency use authorization a week later. Getting lost in the flood of vaccine news? If you're curious about which COVID-19 vaccine is most effective, wondering about how expensive they are, or weighing the differences between each type, comparing COVID-19 vaccines can mean having 14 tabs open on your laptop at once.
These vaccines are the first, out of dozens in development worldwide, to become available to people in the U.S. Other countries have developed and authorized their own vaccines, including Russia and China. Many other vaccine candidates are now in Phase III trials, to determine how effective they are at preventing COVID-19 in humans. A new variant of COVID-19, believed to be more infectious, was found to be circulating globally in December, and that may have implications for how effective vaccines are in the long term.
Here's your roadmap to the vaccine landscape as it stands, including the latest deets on efficacy, trial results, FDA authorization, cost, and what scientists don't yet know.
How Do The COVID-19 Vaccines Work?
There are several types of COVID-19 vaccines currently available and being tested. Both Pfizer and Moderna have created vaccines that inject part of COVID-19’s genetic code into your body in two doses, per the BBC. It's an experimental technique using mRNA, a molecule that turns genes into proteins, according to The Guardian, and it seems to be highly effective in training the body's immune system to recognize and fight COVID-19.
The AstraZeneca vaccine, which was produced with the University of Oxford and is not yet authorized in the U.S., takes a different approach. The BBC reports that it's a genetically modified common cold virus that often shows up in chimpanzees. The virus has been altered so nobody will catch the cold itself. Instead, it introduces COVID-19's proteins to the human immune system, training it to protect itself.
A major difference in the vaccines has to do with how they're stored and transported. The Pfizer vaccine has to be stored at -100F, which requires a supply chain of deep freezers so it won't spoil, per CBS. The Moderna and AstraZeneca vaccines, meanwhile, can be stored in ordinary fridges, according to The Guardian, making them easier to distribute.
How Effective Are The COVID-19 Vaccines?
According to preliminary Phase III trial results, Pfizer's vaccine has been shown to be 95% effective in protecting people from COVID-19, per trial data released by the Food & Drug Administration (FDA), while Moderna's is 94.5% effective, according to CBS. To measure efficacy, the researchers looked at how many people in each trial got COVID after receiving a vaccine, compared to those who got COVID after getting a placebo. Moderna has also released data suggesting that it's equally effective across all racial and ethnic groups, per Science. Pfizer's vaccine, meanwhile, only drops to 94% effectiveness in people over 65, according to the BBC.
Working out the effectiveness of AstraZeneca's vaccine is a little more complicated. Thirty people who’d had the two-dose vaccine tested positive for COVID, compared to 101 people who received a placebo. That works out at 70% effective. But the AstraZeneca team reported in a press release that it tried two approaches: two high doses of the vaccine, and one low dose followed by one high dose. The BBC reports that the two high doses were 62% effective in protecting against COVID, but the low-high dose regimen was 90% effective in all ages. According to the full trial data, released in The Lancet in December, the low-high dose was actually an accident in a small number of patients, and the result needs to be replicated before it can be confirmed. Until then, AstraZeneca's 70% figure stands.
What Vaccines Have Been Authorized For Emergency Use?
The Pfizer-BioNTech vaccine was given emergency use authorization by the FDA in the evening of Dec. 11. It is now being rolled out across the U.S. for high-priority users, including healthcare workers and people in long-term residential care. Pfizer could produce 600 million doses for the U.S.. The first Pfizer vaccines were administered on Dec. 14, CNN reports, with an ICU nurse in Queens being the first person to receive the vaccine in New York City.The Moderna vaccine was given emergency use authorization on Dec. 18.
The AstraZeneca vaccine hasn't completed its U.S. trial, funded by the U.S. government's Operation Warp Speed and involving 30,000 U.S. patients, but once regulators can look at the data — potentially as early as January — it could apply for FDA authorization as well. According to Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, there is hope that both the Pfizer and Moderna vaccines will be available to "high-risk individuals" before January 2021. President-elect Joe Biden has said he aims to vaccinate 100 million Americans in the first 100 days of his presidency, or by April.
How Many Doses Of Each COVID-19 Vaccine Will You Need?
All three vaccine front-runners currently require two doses, spaced between three and four weeks apart. Biden announced on Jan. 8 that his administration will release all available doses of the vaccine, the Associated Press reported, rather than holding some back. This way, more people can get the partial protection of a single shot more quickly, over waiting to have both doses.
What Are The COVID-19 Vaccines' Side Effects?
To date, Clinical Trials Arena reports, all three vaccine studies have reported that patients may experience mild to moderate side effects, including muscle aches, fevers, headaches, and nausea after taking the vaccine, but that nobody has developed serious virus-related side effects that require medical attention. Trial data for Pfizer's vaccine reveals that mild pain at the site of the injection, light fevers, headaches, and chills are its most common side effects, and they're most common after the second dose.
Do The Vaccines Prevent Severe COVID-19?
As with the flu shot, the vaccine reduces your risk of getting COVID-19 — hence, why the efficacy rate isn't 100%. Still, it's possible that, also like the flu shot, the COVID-19 vaccines will reduce the severity of COVID-19 if you do get it. Moderna's vaccine appears to be extremely effective at preventing severe cases of COVID-19, according to The Guardian, while the BBC reports that nobody on AstraZeneca's trial of 24,000 people developed serious COVID-19. Right now, Pfizer's trial suggests it might be helpful against severe COVID-19, but only 10 people on the trial had severe symptoms, per The New York Times, so it's too small of group to tell. According to its trial data, nine of those people had the placebo, while one had the vaccine.
How Much Will The COVID-19 Vaccines Cost?
AstraZeneca’s vaccine is one of the cheapest; compared to Pfizer and Moderna, which are being sold to governments at $20-25 per dose, per The Guardian, it will be sold at just $3-4 if it’s given emergency authorization by the FDA. Biden has committed to distributing the vaccine for free to all people in the U.S.
Will The COVID-19 Vaccines Protect Against New Variants Of COVID-19?
New variants of COVID-19, which may be far more infectious, were found in the U.K. and South Africa in late 2020, and were discovered to be circulating globally. Scientists were hopeful that the vaccines would protect against these new variants, and got some encouraging evidence in January. A preliminary report in BioRXIV, which has not been peer-reviewed, shows the Pfizer vaccine may protect people against this variant, as well as the original virus. The study only focused on one of the mutations in the new variant — there are a few — but the Pfizer vaccine was able to fight it off. More testing needs to be done, but it's a great sign.
What Research On The COVID-19 Vaccines Still Needs To Be Done?
According to USA Today, none of the vaccine trials have yet released data on how they might affect pregnant people. 23 people in Pfizer's trial became pregnant during the trial period, and while nobody in the vaccine group reported any adverse reactions during pregnancy, there's no other data about how it might affect them long-term. Dr. Fauci has said that vaccine trials on children and pregnant women may start from January, per CNBC. It's also unknown how long each vaccine will remain effective; while Pfizer's lead scientist told The Guardian that its two-dose vaccine will keep somebody protected for up to a year, nobody has precise data on that point yet.
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