Prior infection provides effective protection against Covid-19
New study shows that naturally acquired immunity is equivalent to vaccine; we finally need to test for (and discuss) T-cell immunity
A new study was just pre-published under the title “Protection of previous SARS-CoV-2 infection is similar to that of BNT162b2 vaccine protection: A three-month nationwide experience from Israel.”
The study compares the efficacy of the Pfizer vaccine to the efficacy of naturally acquired immunity (i.e. through a previous infection with Sars-Cov2 or similar virus). The results show that naturally acquired immunity is equivalent to immunity acquired through inoculation. In fact, naturally acquired immunity does a few percentage points better than the Pfizer vaccine. This is an extremely important finding, not only because it proves what I have personally always considered intuitively and logically true based on what we know about viruses and immunity. But apart from my own ego, it’s important because the topic needs to enter the following public discussions/decisions:
- Events, airlines, countries, etc requiring vaccination to enter: Proof of a prior infection and T-cell immunity must be equivalent to proof of vaccination. You might not have had a test while you had the virus, so you have no PCR-test to prove a prior infection. During infection your antibodies would have been high, but we know by now that they subside over time, so a delayed antibodies test doesn’t mean much either. But T-cells are the part of the immune system that offer long-lasting immunity in the case of Covid-19, so this should be the crucial test result to demonstrate a prior infection and immunity. Luckily some countries get it, for example Iceland now allows fully vaccinated travellers as well as people who can prove a prior infection to enter the country waving some entry requirements (such as a PCR test and quarantine). Similarly, Germany is discussing privileges to vaccinated people and those with prior infection.
- Vaccine shortage: If previously infected people don’t need a vaccine, we can focus on vaccinating people who need it. The numbers are guesswork of course, but with current figures we can estimate that possibly over 140 Million people have recovered from Covid-19 — if they don’t need to be vaccinated, that frees up 140 Million doses.
- Social media posturing: Getting vaccinated doesn’t make you a hero, if you’re already immune. Get your tests and facts straight, before you try to shame others — instead raise the quality of public discourse and encourage your friends to get the proper tests so everyone can make an informed decision.
- However, accepting proof of T-cell immunity still doesn’t solve the situation entirely. There is a large part of the global population not at risk of developing Covid-19. And those not at risk of getting sick or running a very mild course of the disease are not likely to transmit it to others. Getting back to the first point about personal freedoms and the right to move around freely, it is highly questionable to force an entire population to get vaccinated when a large portion really doesn’t have a need for it. I strongly encourage policy-makers to come up with reasonable solution so as to not discriminate against several generations. There is enough scientific data out there now for someone to come up with solutions, if they just put theirs heads to it rather than trying to solve everything with disproportionate blanket measures.
Note that the above study is in pre-print, i.e. it has not gone through the peer-review process yet. That doesn’t mean the findings are invalid, it just means that the study should not yet serve as a guide for any medical or societal policies. However, I consider it crucial for governments and the media to pick up this conversation now, because based on evidence I regard it extremely likely that many other studies will throw up similar results. Partially pointing in that direction are other studies that recommend previously infected people do not need two shots of the Covid vaccine.