Covid-19 Vaccines: Is This the Beginning of the End?

Although we might also wish for a digital vaccine against the ugly rumors that circulate on our social platforms, right now we are expectantly looking at the possibility of a real vaccine against a real virus, the one that causes Covid-19. This is devoutly to be desired, but a lot of questions remain. 

Just to review, a vaccine generally is something that includes some part of a nasty bacterium or virus, or includes a chemically inactivated form of the whole thing. When injected into your body, the presence of those molecules stimulates your immune system to build immunity and to remember how to recover that immunity if the bug ever attacks you again. 

In short, for most of us, once we had the measles, we don't get it again, and people a bit younger who got the measles vaccine (two shots) generally don't get it ever. 

The world has been expectantly awaiting the creation of a vaccine for Covid-19 since we first heard about the disease getting loose into our population. Since Monday, we've moved into a new episode in the Covid-19 era -- it's the moment when we can hope to be moving into the post-Covid-19 era. 

So now -- Pfizer and its mRNA vaccine 

We've all read how Pfizer (try learning to spell that word on your typewriter) is basing its claims of vaccine efficacy on 94 cases of the illness. That doesn't seem like a lot. If you began an experiment using 94 people, you wouldn't have a lot of scientists believing in your results. But they didn't just start with 94 people. They actually started with more than 40,000 human volunteers. 

They made up syringes that were coded, and presumably half of them had the vaccine and the other half just had sterile saline (essentially salt water) or something equally innocuous. Give those 40,000 needle sticks to the volunteers and then give them a second injection (what we used to call a booster) and see what happens. 

Research grants often include, when describing a proposed experiment, a section on the expected results. In this case, the hoped for result would be that nobody who got the actual vaccine got the disease. If any did get it, you have to evaluate that number against the number who got it in the saline-injected group. 

By the way, this kind of study is useless if nobody in either group gets Covid-19. That's because you can't know that you are protecting people from the virus if nobody is getting it anyway. 

But if lots of people in the control group are getting the virus (the ones who are only getting the innocuous saline), then you have something tangible to compare against. Let's say that 85 people in the control group got the virus -- they didn't have the Covid before, as you have shown by direct testing and by antibody tests -- and now they've gotten it, as shown by careful testing and presumably some symptom of the illness. (This by the way is why these studies need peer review. Some group of outsiders who don't have their personal egos in the game will check every data point and calculation, and then evaluate all the logical thinking that was used in the analysis. And one question they will be asking is whether the supposed Covid-19 cases were really that, as evidenced by symptoms and not just the throat swab.) 

Now there is one more assumption we will make. It is this -- since the control group got 85 cases -- the vaccine injected group would be expected to get somewhere around the same number of cases if the vaccine is not working. Maybe it won't be exactly 85, but it ought to be somewhere in the same ballpark, say somewhere in the range of 65 to 105. 

But maybe the vaccine is working. How would you know? 

Suppose there were only 8 cases of Covid-19 in the vaccine-injected group. That would be a pretty strong indication that the vaccine is doing something to prevent symptomatic cases. Instead of getting 65 or 85 cases, they only got a few. 

As best as I can see, this is pretty much what Pfizer is trying to tell us. The vaccine-injected people had a lot lower number of symptomatic Covid-19 cases than the control group. Right now, Pfizer is suggesting that the vaccine is as much as 90% efficacious. If I understand, that would mean that if you get the vaccine and then you are exposed to the virus, you have about a 90% lower chance of getting sick than you would have had otherwise. The official way of presenting the statistics and probabilities may be a little different, but this is the basic idea. 

If that 90% number holds up, it is actually pretty good news, because at least we would have something that works better than the yearly flu vaccine. You would have a much better chance of being exposed to the virus without falling deathly ill. 

The question that journalists have been asking (but not as yet getting answers) goes like this: Does this vaccine completely prevent you from getting the disease -- meaning the virus doesn't grow in you -- or is it just protecting you from feeling really sick, even while you carry the virus and shed virus into the air and water? 

This turns out to be a really important question, because it involves whether we can effectively eradicate the Covid-19 from the human population, or at least get it way, way down to manageable levels. 

Alternatively, are we stuck with the equivalent of the seasonal influenza, where the virus will continue to circulate through the human population. Some people will get it and pass it along to others, even though the vaccine saves them from feeling sick. Some of the population won't get vaccinated, and they would be subject to the full bore illness. Even some vaccinated people would, under this scenario, get Covid-19, and a few of them would die of it. 

That's why it's such an important question as to whether this vaccine fully prevents us from getting infected. 

Let's imagine for the sake of argument that the vaccine prevents us from getting the infection at all. Here is how it could be used to eradicate (mostly) the Covid-19 illness from the human population. The basic idea is called herd immunity. 

You can look it up on Wikipedia or find it on the internet, but (without adding in the mathematics), here is the basic idea: If you have an infectious case of the disease (say you just got off the airplane from a region where it is endemic) and most of the people around you are immune, you are not going to give it to them. Maybe there will be one person who gets it from you, but since he also is surrounded by people who have immunity, he is not going to give it to a lot of people. You've possibly heard of the likelihood that any one person with the virus gives it to somebody else, and a correlated number called R₀ which describes how many other people get infected by any one infectious person. 

The idea of herd immunity is that even if you are infectious, you can't give the disease to very many people if the people around you can't themselves get it. 

So the first part of eradicating Covid-19 from the human population is to inoculate as many people as possible with the vaccine. It may be that even with one-third of us inoculated, we will have some partial level of herd immunity, and as we get to one-half and then three-quarters of the population, we will be pretty close. We can feel pretty sure that if we could inoculate 95% of the population, we would have the disease pretty well in check, and we could throw away the masks, open the bars, and all have a celebratory drink. 

There is no doubt in my mind that this country, along with Europe and Asia, could eventually make and inject enough vaccine doses to accomplish this level of nearly total coverage. We won't know for sure that it works to protect nearly everyone until we have tried it, but if it works on the first 45,000 people then it probably will work on the rest. 

Difficult questions 

There may be other ways of creating a workable vaccine. Actually, nobody has ever made a workable vaccine in quite this way before. Without going into the molecular biology, it involves creating a factory-made, artificial version of something called messenger RNA, then getting it into the people you want to protect, and knowing that when it gets inside of you, it will result in your body producing part of a protein that mimics a part of the real virus. Then your body has to react to that part of a viral protein the way it would react to a real viral infection. 

The overall idea isn't that startling. A couple hundred years ago, Jenner used a live virus from cowpox that just happened to mimic smallpox enough that your body would react in a way that would make you immune to smallpox. Not only did it work, it eventually was used to eradicate smallpox from the entire human population. 

 So one question is this: Should we wait for a more conventional vaccine that is made from a weakened version of the live virus, or uses a killed version of the virus (like Jonas Salk did with polio) or any of the other more traditional ways of making a vaccine? 

Also, will an mRNA vaccine show some inherent danger to humans that we won't find out for a while? The answer is probably No, but the manufacturers and the FDA and other regulatory agencies around the world will be looking at the clinical data (as well as all the theory and theoretical studies) to be as absolutely sure as possible that the vaccine is really, really safe. 

Political difficulties 

It's no secret that there are a lot of people who are adamantly opposed to the use of vaccines. There were such people in Jenner's day, but the modern internet has given the present generation an advantage. Almost from the beginning, they started a campaign to discredit both Covid-19 and the future use of any Covid-19 vaccine. Some of them even joined in the paranoid claim that the Covid-19 is a hoax, or was the product of some government lab, or whatnot. In any case, we can expect a lot of irrational nonsense about the dangers of vaccines coming from them. For once, they have had a bit of concern from the pro-vaccine side (i.e.: nearly everybody else with half a brain), largely because the pro-vax people were worried that the current presidential administration was trying to push the whole project too fast, and to cut corners on safety. 

It would appear that the drug companies have pushed back, and we will probably eventually be convinced that the process to prove the new vaccines will have been honest and thorough. 

Tracking and surrounding the cases 

Politicians have been tossing out arguments about why we need to be doing more testing, so that we can track the new cases and get them properly quarantined. This doesn't seem to be a very practical approach in this country. One reason is that we are a fairly independent and stubborn people, and we don't take orders very well. Most of us mean well, and Los Angeles has been pretty good about the masks, but we see a lot of socializing that goes far beyond the early lockdown days. 

But equally important, I would argue, is that it is hard to make use of tracking data when the entire population is at risk. Suppose you check on a case of Covid-19 in a checker at the local supermarket. He may have been breathing out live virus for two or three days before he got a fever -- and now what? Are you going to track down the last 300 people that handed him groceries? In Los Angeles county, the statistical likelihood is that the vast majority are at risk. 

But suppose you can count on the fact that 90 percent of those customers had the vaccine. Then you could track down customers and offer the vaccine to the small number you discover who are at risk. 

And if you discover a case of Covid-19 in a student living in a dormitory, you could inoculate every other resident of the dorm who has not, as yet, had the shot. You will be able to surround any one case by vaccinating everybody who is near. 

In a population that already has some herd immunity, it should be easier to tamp down any flareups of the disease in our population.

(Bob Gelfand writes on science, culture, and politics for CityWatch. He can be reached at [email protected])

-cw