TThe US Centers for Disease Control and Prevention (CDC) has failed to recognize that people with confirmed Covid infection, also known as “natural immunity,” have achieved some level of protection against subsequent infection and severe illness. This has fueled unnecessary divisions, especially when vaccines were mandated without prior recognition that Covid was an alternative pathway, albeit with some limitations, for individual protection and helping to build a population immune wall.
While there is a data set that supports a strong immune response to Covid infection, the evidence is currently substantially supported. In a very large trial on a single injection of the Johnson and Johnson vaccine Compared with placebo, among more than 2,000 participants with previous infection, as documented by positive antibody status, their protection against moderate or severe disease was 90%. That’s much higher than the 56% vaccine efficacy, but the CDC recognizes this 2-shot vaccine as a “full vaccination” but ignores this data, and many other points of evidence, of natural immune protection.
Recent CDC report for Covid-19 in California which included the Delta wave, the cumulative hospitalization rate for the vaccinated was 0.7% among the vaccinated and 0.3% among the unvaccinated with a previous infection. In particular, a 10-fold lower risk of subsequent infection was found in people with natural immunity compared to those who were vaccinated. Cleveland Clinic health system study of more than 52,000 employees. These reports convey high levels of natural immune protection, sometimes comparable to a 2-shot vaccine. Several studies follow people at least 15 months out of the Covid infection has shown persistent antibody level and sel B memori. Re-infection among those with natural immunity during the pandemic, up to the recent Omicron wave, was very low, less than 1%. A study in England of about 9,000 people with previous infections showed higher than 90% protection against subsequent infections, even among those who had Covid more than 18 months earlier.
If there is good protection from infection, then why are single-use vaccines necessary and sufficient? A new report of nearly 150,000 people with Covid infection in Israel, with about half vaccinated, compared with others who were not vaccinated, there was an 82% lower risk of reinfection for people 16 to 64 years of age, and 60% for those 65 years of age or older. There was no difference for protection with more than 1 dose of vaccine. The same was found in other studies. Both were performed during the Delta wave, but now we have data with Omicron, the type of virus with the most substantial evasion of our immune system. prove that, Di Qatar, while natural immune protection was around 90% for the previous Alpha, Beta, and Gamma variants, dropping to 56% for Omicron. In the UK, the risk of re-infection for people with Covid previously jumped to a level 16 times what was previously seen. But a Cleveland Clinic’s Omicron wave study on approximately 8,000 people with natural immunity, 1 injection of the vaccine markedly reduces the risk of infection and 2 or 3 injections has no additional protective benefit. Similar findings were consistent in Israeli and British studies: 1 shot worked, no additional protection from 2 or 3 shots. Indeed, fading of protection after 1 year in the UK study was prevented by a single dose of vaccine.
Past criticism of natural immune protection is still relevant. These studies have a survival bias—only include people who have survived their infection. We know that the symptoms of Long Covid can be reduced by vaccine, which is an important additional feature of the controlled vaccine approach compared to the unpredictable chronic duration of infection, which can be disabling, even when mild. Although about 90% of people with infection develop antibodies and memory B an T cells, it does leave some people with an immune response, which seems to be more of a problem when a person has no symptoms, or the symptoms are very mild. Because we did not assess the level of antibodies, particularly those capable of neutralizing the virus, and did not measure the T-cell response, there is a blind spot in knowing an individual’s level of protection, either through infection or vaccination.
Which brings us to hybrid immunity. It would be very reckless to recommend someone knowingly be infected with Covid. However, for those who have developed an infection, their immune response is directed across the virus whereas our vaccine is specific to the spike protein. The result of combining different immune responses is a synergy, more than additive, strong and durable protection, 25 to 100 times more antibody response and wider range of viral variants.
It is now clearly too late for the United States and the CDC to recognize natural immunity as a partial path to protection, as some countries have done before. The term “complete vaccination” needs to be redefined. For people who have received 2 injections of the mRNA vaccine, without previous infection, a third shot, a booster, is needed to protect against symptomatic and severe disease. On the other hand, for people with natural immunity, with evidence of a positive PCR test, a one-shot is all that is needed to be considered a “full vaccination.”
By certifying immunity in this way, the polarization between the natural and vaccine-induced immune camps will be bridged, at least to some extent. The evidence has been overwhelming and its implementation as a policy is likely to help get America’s low vaccination rate of 64%, ranked worse than 60 countries in the world, to a much higher level, further building a wall of immunity for the entire population.
It’s also about holding on to science when large and ever-growing data sets can no longer be ignored. One can fully understand why vaccine mandates would be denied when there is evidence of the protection afforded by infection. Now, as the virus evolves, we are at a time when natural immunity alone is not enough, but with one shot it is as good as three.
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