A New Italian Study Reveals Omicron Much Less Dangerous Than Previous Strains
I found a recent Italian study that is in preprint. You can read it here. The paper uses Italian statistics on the infection rate, hospitalizations, ICU admissions, and deaths from the different strains of the SARS-CoV-2 Virus. The authors used what appears to be reliable, high-quality data and analyses. I will break down some details later, but the authors noted that hospitalization, admission to intensive care, and death from infection with the Omicron variant phase are at least 20 to 40 times less than the initial acute phase.
The Study Used Quality Data and Analysis
The authors understood that the initial phase data was under-reported due to a lack of reporting and testing. To circumvent this disparity, the authors provided infection ascertainment ratios, which could then be factored into the calculations over time for a clearer picture of events. They also utilized infection attack rates, population susceptibility to infection, and probability of adverse outcomes from SARS-CoV-2 infection.
The Five Phases of SARS-CoV-2
The period of data fell between February 21, 2020, and February 20, 2022. The 5 variants were divided as follows:
Phase 1 (ancestral) from February 21 to June 30, 2020.
Phase 2 (ancestral) from July 1, 2020, to February 17, 2021.
Phase 3 (Alpha) from February 18 to July 1, 2021.
Phase 4 (Delta) from July 2 to December 23, 2021.
Phase 5 (Omicron) from December 24, 2021, to February 20, 2022
Increasing Infection Rates with Each New Strain
The first two phases are associated with the circulation of ancestral SARS-CoV-2 lineages. The initial sudden attack threatened to overwhelm the Italian healthcare system, but the infection rate in phase 1 was only 2.8%. The infection rate in phase 2 increased to 11.4%. The ancestral variants equally infected all age groups. The infection rate of Alpha in phase 3 was lower at 10.1%. In phase 3, the youngest group had the highest infection rate, while the oldest group had the lowest. The researchers attributed the decline in elderly attacks to the vaccines first given to seniors. Next, phase 4 Delta had an infection rate of 17.3%. Again, younger age groups had higher rates. Finally, phase 5 Omicron infected 51.1% of the population, with many more young people becoming infected. Clearly, the Omicron variant is the most infectious strain. The authors estimate that by February 20, 2022, 68.3% of the Italian population was protected by natural immunity, mostly acquired after infection with Omicron.
Diminishing Returns
At the same time, the researchers estimated that vaccine immunity had waned by February 20, 2022, causing the vaccinated segment to have no immunity to infection. The contribution of unvaccinated individuals to residual population susceptibility was negligible at that time because it was only 2.7% of the population, with a large majority represented by children younger than 10 years.
Probability of Hospital Admission From Covid
The probability of hospitalization per infection in phase 1 was 5.4%. The hospitalization rate for phase 2 went down to 3.1%. For phase 3 Alpha, it went down to 2%. Hospitalizations continued to fall during phase 4 Delta to .56%. Finally, phase 4 Omicron had a hospitalization rate of .27%. The risk of hospitalization has fallen 20 times lower, or 2000%, since the original strain.
Probability of ICU Admissions From Covid
Phase 1 saw an ICU admission rate of .65%, and phase 2 went down to .45%. The trend continued in phase 3 Alpha to .28; phase 4 Delta was .o6%. Finally, phase 5 Omicron had an ICU rate of .018, which is over 12 times, or 1200% lower than the original strain.
Probability of Death From Covid
The phase one ancestral strain had a death rate of 2.2%. Phase 2 dropped to 1%, and Alpha fell further to.44%. Delta came in at .1%, and Omicron had a .05% death rate. The death rate for Omicron is 44 times less than the original strain, or over 4,400% lower. 1
Who Was Dying?
A different study done in Italy concluded that for all phases of the pandemic, the biggest risk factor for death from Covid was age. The median age at death of non-hospitalized patients was 86 years, with 94% being 65 years old and older, while the median age of deceased hospitalized patients was 81 years, with 90% being 65 years old and older as well. Male sex and pre-existing comorbidities were also significant risk factors, according to the authors. 2
The Authors’ Prediction
The authors state that the general trends and conclusions may apply to other high-income countries adopting a similar mitigation approach throughout the pandemic. They also point out that, considering the Italian demographic structure is skewed towards older ages, the decreasing trends in probabilities of adverse outcomes might be even more marked in countries with younger populations. This is good news. I hope they are correct. 1
Evolutionary Pressure of Viruses to Become More Infectious and Less Lethal
The higher infection rate and lower incidence of symptoms and death are largely due to adaptation by the virus and the host. Viruses must rely on hosts to replicate. If they readily kill the host, they doom themselves. So less lethal viruses are typically selected. Conversely, host immune responses that succeed in surviving viral infections are also selected to continue to procreate the species.
Additionally, viruses that can spread easier will outcompete less infectious ones. So, the natural tendency of infectious viruses is to become more infectious but less symptomatic and less lethal. Therefore the 1918 flu pandemic never became the 1918 to 1925 pandemic. The recent pandemic is going the way most others have. At some point in the future, SARS-CoV-2 will likely become endemic, like the common cold. Not to diminish the common cold. A loved one had two colds in the last three years, landing them in the hospital due to other comorbidities. We can’t avoid all comorbidities. For instance, we will age, but we can minimize most of them. Otherwise, the weaker we get, the easier it is to die from disease.
Conclusion
We should stay as strong and healthy as we can. Individuals get viruses, not countries. As much as we like to dice statistics, each case of infection is unique. Our age, immune function, etc., all affect the outcome. We should all strive for a full night of sleep, maximize our daily nutrients, remain active each day, get sun and fresh air, and seek nurturing relationships. These actions and others are vitally important for improving and maintaining health. For additional information on healthy lifestyles, click here and here.