Well, what do you know: A study published in the New England Journal of Medicine from data “based on the total population of Qatar” has concluded that natural immunity is as effective as vaccines at protecting against serious Covid infection, and that a combination of the two (with boosters) provides the most protection. From “Effects of Previous Infection and Vaccination on Symptomatic Omicron Infections” (my emphasis):
No notable differences were observed in the effectiveness against BA.1 and BA.2 of previous infection, vaccination, and hybrid immunity. Protection from previous infection with variants other than omicron against reinfection was moderate and durable, but protection of primary-series vaccination against infection was negligible by 6 months after the second dose.
Recent booster vaccination had moderate effectiveness, whereas hybrid immunity from previous infection and recent booster vaccination conferred the strongest protection against infection, at approximately 80%. All five forms of immunity were associated with strong and durable protection against Covid-19–related hospitalization and death.
It seems as if natural immunity provides as good protection as the two-vaccination regimen:
The protection conferred by hybrid immunity of previous infection and two-dose vaccination was similar to that of previous infection alone, at approximately 50%, which suggests that this protection originated from the previous infection and not from vaccination. This finding is also explained by the short-lived protection of primary-series vaccination against omicron infections.
But booster inoculations did help:
However, the highest effectiveness was seen with hybrid immunity from previous infection and recent booster vaccination (approximately 80%). This finding provides evidence for the benefit of vaccination, even for persons with a previous infection. Strikingly, this protection is what one would expect if previous infection and booster vaccination each acted independently. Because previous infection reduced the risk of infection by 50% and booster vaccination reduced it by 60%, the reduction in the risk of infection for both combined, if they acted fully independently, would be 1−(1−0.5)×(1−0.6)=0.8, which is an 80% reduction, just as observed.
What should we take from this? The time has come to put the vaccine-mandate controversy to bed. So, while vaccines and boosters certainly seem to be worth taking:
Even though the five forms of immunity investigated showed large differences in protection against symptomatic infection that ranged from 0 to 80%, they all showed strong protection against Covid-19–related hospitalization and death, at an effectiveness of more than 70%. This suggests that any form of previous immunity, whether induced by previous infection or vaccination, is associated with strong and durable protection against Covid-19–related hospitalization and death.
Meaning: Natural immunity should count as much as vaccinated status in determining risk of serious illness. More broadly, coercion to force vaccination is not defensible as a matter of policy. The mandates should be repealed. Military members who refused vaccination should not be discharged. People in the private sector who lost their jobs because of the vaccine hysteria should be reinstated. Anyone adversely impacted by their personal decision to remain un-vaxxed should be made whole.