These Covid-19 Vaccines Are Really Good

This week, the FDA approved a second vaccine against SARS-CoV-2, the virus that causes Covid-19. We now have two highly effective vaccines, one from BioNTech and Pfizer, and the other from Moderna. A third vaccine, from the University of Oxford and AstraZeneca, is very close to being approved.

The two new vaccines, both based on RNA, are remarkably effective. Below, I will summarize some of the issues that have been released for the world to see.

This is a scientific triumph. Less than a year ago, no one outside of China even knew this virus existed. The genome of the virus was first released in January, and within a few months, scientists had designed the first vaccines. Clinical trials began immediately, and larger trials followed, leading us to where we are today: two new vaccines, tested and validated in tens of thousands of people, now manufactured and shipped in billions.

For anyone who might be skeptical, or just wants to know more, the test results are openly published. the New England Journal of Medicine has a dedicated website with dozens of articles and audio summaries, including the results of large-scale (Phase 3) trials of the Pfizer vaccine.

Before we get into the numbers, let’s summarize what these two new vaccines are. (I wrote about this in July, if you want to read my explanation above.) Both are RNA vaccines, which is in itself a spectacular advance. RNA vaccines have been discussed for years, but the technology was never used for human vaccines until now.

Here’s how they work: our immune systems (which is super complicated, as Ed Yong explained in The Atlantic) recognize microscopic invaders and destroy them. Once you’ve been infected with Covid-19, the immune system swarms over the viral particles and basically learns what they look like. SARS-CoV-2 has a protein across its surface called “Spike”, so that is what the immune system recognizes.

After you’ve fought off the infection, your immune system remembers what Spike is like. If you are infected again, you can respond much faster, so you won’t get sick. This is what we call acquired immunity.

So for vaccines, the trick is to teach your immune system to recognize Spike. One way to do this is to make lots and lots of the Spike protein and put it in the vaccine (sort of, I’m oversimplifying here).

But with modern genomic technology, we can use a different approach. Every cell in your body has machinery inside it to translate RNA into protein. As soon as we had the SARS-CoV-2 genome, in January, we learned about Spike’s genetic code. So instead of making the protein, what if you just made the RNA, which is much easier and faster to make, and injected it into people? Do our own cells then translate the RNA and make the Spike protein?

Well yes, they do. And not only that, but as Modern and Pfizer clinical trials have shown, our immune systems recognize that Spike protein is strange (it’s complicated) and launch an attack.

So to make an effective RNA vaccine, you simply have to inject enough RNA for the immune system to respond. That’s what Modern and BioNTech / Pfizer vaccines have done.

Now let’s look at the numbers. As reported in NEJM just two weeks ago, the Phase 3 trial for the Pfizer vaccine evaluated 43,448 volunteers, of whom 21,720 received the vaccine and 21,728 received a placebo. At the time of the report, 162 people who received the placebo had become ill with Covid-19, but only 8 people in the vaccine group became ill. That’s a 95% reduction in disease, a remarkably good result. They also reported that 10 people had a “serious” illness and 9 of those 10 were in the placebo group.

How about the Moderna vaccine? This vaccine has almost identical efficacy, published in a preliminary report a few weeks ago as 94.5%. Just a few days ago, an FDA review panel approved the vaccine and confirmed that it was above 94% effective. And the modern vaccine doesn’t need the very cold freezers that Pfizer vaccine does, making it easy to distribute.

Both vaccines have minimal side effects in most people, mainly pain at the injection site and sometimes headaches or chills, which go away within a day. RNA breaks down rapidly in the body, so there is no reason to expect persistent side effects from these vaccines.

There is also growing evidence that immunity lasts for many months, if not years. Another report in NEJM, on the Moderna vaccine, contains some of the most recent data, showing that immunity is still strong after 4 months. Of course, with a new vaccine, we just have to wait to see if the immunity lasts for years, but all the signs are positive at this point.

So yes, these are really good vaccines. I will get mine as soon as I can, although I guess I will have to wait several months due to the shortage.

(The Oxford / AstraZeneca vaccine, a more traditional protein-based vaccine, has also shown positive results, either 62% or 90%, depending on the dosing regimen, but the 90% results are based on fewer cases. well, it is clearly effective and should be approved soon, at least in the UK. So soon we could have 3 vaccines).

A note to anti-vaccines: no, you I can not get Covid-19 from these vaccines. They do not contain the virus! They only have one RNA fragment of a protein, and the virus has RNA that encodes 28 other proteins. It is simply impossible for the virus to self-assemble without the rest of its genome.

But hey, if you don’t want the vaccine, go to the end of the line. Most of the world is desperate for it.

The success of RNA vaccines is a great victory for science, but even more, it is a great victory for the human population. We are still many months away from vaccinating the entire world, but with two highly effective vaccines, we can finally have hope of ending this pandemic.