This commentary is by Tom Evslin of Stowe, an entrepreneur, author and former Douglas administration official. It is republished from the Fractals of Change blog.
The numbers we hear in the nightly news consistently undermine the importance of vaccination even though the intent is to do the exact opposite. Problem is that neither political leaders nor most reporters know much about statistics. There’s enough misinformation current so you certainly should ask why you should believe my applied statistics 101 in this post. I’m not an epidemiologist or even a medical professional; I didn’t sleep in a Holiday Inn Express last night. I have made my living with statistics-based software which controls things in real time based on statistical information and I have some related patents. Still, you should be skeptical and judge whether what I’m saying makes sense.
What does 95% effective mean?
Developing vaccines which were initially “95% effective” at warp speed was an enormous achievement even though the efficacy wanes with time and is reduced by mutations. But what does 95% effective mean? Does it mean that you have only a 5% chance of getting Covid if you’re vaccinated? NO. Definitely not! It means that people who were vaccinated in the study groups were only 5% as likely to get symptomatic Covid as those who were given a placebo. If 500 out of 10,000 unvaccinated people got Covid, the studies are saying that only 25 similarly situated vaccinated people had symptoms. That’s huge and that’s the reason the vaccines were quite properly authorized for emergency use almost as soon as these results were available.
What if everyone were vaccinated?
Then all cases would be breakthrough cases but there’d still be cases. If the chance of an unvaccinated person contracting symptomatic Covid at a particular time and place during any given month is 2% and vaccinated people statistically have 95% protection (5% breakthrough rate), then the chance of a vaccinated person getting infected is 0.1%, a small number but not nothing. If 300,000,000 of us are vaccinated and the breakthrough rate is 0.1% (numbers for illustration only), then we’d still expect 300,000 cases per month. 100% of these would be breakthrough cases. Would that mean the vaccines aren’t working? Of course not. Without them there would’ve been 6 million cases, 20 times more.
Moreover vaccinated people are saving the lives of the unvaccinated by reducing the overall spread rate. If everyone were vaccinated, cases would quickly become rare and far between and then almost non-existent in the vaccinated population – fingers crossed on mutations and booster shots.
What to watch for
As more people are vaccinated, the number of symptomatic Covid cases among vaccinated people will go up. As we have less unvaccinated people the number of cases among the unvaxxed will go down. The numbers that are important are the rate among the vaccinated and the rate among the unvaccinated. These rates are confirming the efficacy of the vaccines although both the Delta variant and the apparent waning of effectiveness are muddying the waters. Both rates will go down as the unvaxxed get a free ride from the vaxxed – fingers still crossed on mutations and booster shots.
But immunity doesn’t mean you can’t get Covid
Even if a vaccine is 100% effective (none are), they don’t stop you from getting infected. Your immune system has no way to destroy pathogens before they enter the body. It can only fight them on home territory. Even if we are “immune” because of either prior infection or vaccination, pathogens we come in contact with do establish small beachheads on our bodies before being repelled by the prepared immune system. Unfortunately in the case of Covid even those beachheads – often too small to be noticed – can be the staging ground for infecting someone else. We vaccinated people are much less a breeding ground for virus than the unvaxxed; but we can still spread the disease.
95% effective doesn’t mean 95% improved protection at the individual level
Vaccines work by preparing your immune system to fight a particular pathogen. If you have a strong immune system, that preparation may well be enough to assure that it will always defeat the pathogen before it is a serious threat to you. On the other hand, if you have a weak immune system because of disease or treatment for disease, you will have a much smaller chance of beating back the disease. Your immune system will be forewarned but outgunned. The 95% statistic is a group statistic and useful for populations but not individuals. It is a blend of those for whom the vaccine is close to 100% effective and those for whom it is not very effective at all. That’s why the immunocompromised need – and are going to get – boosters ASAP.
And in conclusion
Get the damned shot if you haven’t. Get your booster as soon as it is available. And, even if vaxxed, wear your mask where there is high likelihood of getting or transmitting disease.