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Multiple companies and organizations have announced early results about their COVID-19 vaccines. Here's what we know about Pfizer's.

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Go to   to learn how you can take your  STEM skills to the next level. Also, as our usual disclaimer, this  episode was filmed on November 17,   2020, and you can find any newer COVID-19 coverage  in the playlist linked in the description. [♪ intro].

It’s been a big week for COVID news!

 In one corner, the northern hemisphere is entering   flu season. So researchers are trying to figure  out more about how these two diseases interact. And among other things, they’re finding some early   evidence that maybe a flu shot  could protect you against both?

Then, in the other corner, there’s  been a whole lot of vaccine news   from companies like Pfizer, Moderna, and more. So, let’s dive in. As far as the flu and COVID goes, we do have  documented cases of people getting both viruses   at once.

But there’s a lot we don’t know  — including how common this is going to be. But! If there’s any good news, it’s that some  preliminary research is starting to suggest   fascinating — and encouraging!  — things about the flu vaccine.

We already knew flu shots have  a huge impact on flu outbreaks.  Like, the US Centers for Disease Control estimate  that they prevented 7.52 million infections, over   100 thousand hospitalizations, and 6300 deaths  in the US during the last flu season alone.  And that’s because the vaccine   teaches the body to specifically spot  and eliminate multiple flu strains. But that’s not all it does. It also seems that some versions  of the flu vaccine may ramp up   your nonspecific immune defenses, a  phenomenon called trained immunity.  It seems like exposure to a  pathogen — even the harmless   versions in a flu vaccine — can ready  the body’s front line immune cells.  These may essentially become “primed” to react  more aggressively in the presence of danger. 

  And those faster, stronger reactions may  help rally the immune system to fend off   a second invader, even if it’s completely  different—like the virus behind COVID-19.

A July preprint may even show  this trained immunity in action. Preprints are scientific papers that  haven’t been reviewed by independent   experts yet — so our understanding  of their results might change. But since COVID is so new, they’re all  we’ve got to go on in a lot of cases.

In this one from July, researchers analyzed  over 92,000 confirmed COVID-19 cases in Brazil,   and they discovered that receiving a recent  flu vaccine was connected to fewer deaths   and less severe infection overall. This isn't the only preprint suggesting  that populations with good flu shot coverage   have fewer cases and less  severe COVID-19 infections. But like I said, this is only a  preliminary study — and a flu shot   is no substitute for a proper COVID vaccine.

But as folks in the northern hemisphere head into  flu season, it might at least be a silver lining. And speaking of vaccines: In the last week,   multiple companies and organizations have  come out with early results about their   vaccines — from Pfizer and Moderna,  to groups from Russia and China. Each group is saying that their vaccines are  doing really well, according to early results.

But we’re just going to focus on  the Pfizer announcement for now,   because that’s where we’ve been  getting the most questions,   and where we’ve had the most time to  like, take in and synthesize information. On November 9th, Pfizer and their partner  BioNTech announced some early phase 3 trial   results, courtesy of an independent  data safety and monitoring board. According to their press release, getting  two doses of their COVID-19 vaccine three   weeks apart cut symptomatic COVID-19 cases  in the trial population by more than 90%.

Which sounds amazing! But these are also really early results.  They aren’t even published in a preprint,   so experts haven’t been able  to look at the study data. Also, that 90% figure is based on the first  94 infections that occurred within a month   of the participants’ first injection  of either the vaccine or of a placebo.

So, that efficacy number may  change as more data comes in.  And of course, there are still a lot of unknowns,   like whether the vaccine stops people from  catching the disease or from being contagious,   or just prevents infections  from developing symptoms.  So, this is extremely encouraging  but also very preliminary.  
And there’s an even bigger point here, too: even  if this vaccine is as effective as it sounds,   getting it to everyone probably  won’t happen quickly or easily.  That’s because this is a brand new type of vaccine  that uses RNA to essentially teach cells to spot   the virus. And it’s super fragile and needs to  be kept very cold—like minus 70 degrees Celsius.  For comparison, freezers in large hospitals are  usually around minus 2 to minus 8 degrees celsius. So, some experts have warned that   no one has the capacity to do this kind  of distribution on a wide scale yet.  And of course this may be  especially a big issue in   rural areas, and low- and middle-income countries.

Now, not all COVID vaccines in development  require these kinds of extreme temperatures.   So maybe this won’t be a  problem we need to overcome. In the meantime, this is definitely a  reminder that making a working COVID vaccine   is just the start of things. And also, ya know, get your flu shot too!

Which, I did, just the other day. And it went fantastically. Didn't even hurt the next day!

There’s a lot that goes into making a COVID-19  vaccine, and while we can’t give you a tutorial on   how to do it, we can at least say that Brilliant  can hook you up with some good biology courses. Brilliant’s courses are designed by math  and science educators, and cover science,   engineering, math, and computer science topics.  If you liked this episode, you might  enjoy their Computational Biology course,   which deals with subjects  like genetics and evolution. To try it out, you can go  to   And if you’re one of the first 200  people to sign up there, you’ll get 20%   off the annual Premium subscription  — and support SciShow along the way. [♪ outro].