The ongoing coronavirus disease 2019 (COVID-19) pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) had major impacts on healthcare, the economy, and society. However, the cumulative deaths remained lower than those during the Spanish flu pandemic that emerged in 1918-1919.
Several deadly pandemics have emerged in human history that have either disappeared or turned into epidemics due to the impact of herd immunity and virus attenuation. The Influenza A virus H1N1 led the pandemic to turn into an endemic while SARS-CoV(-1) and Middle East respiratory syndrome coronavirus (MERS-CoV) did not reach the same heights of infection rates.
However, prediction of the future trajectories for SARS-CoV-2 remains difficult especially with the emergence of the recent Omicron (B.1.1.529) variant. There is some recent evidence that suggests that the Omicron variant may have some intrinsic attenuation which along with increased vaccinations may give rise to a new chapter in the COVID-19 pandemic.
A new study published on the In Review* preprint server investigated the clinical impact of the pandemic during three different periods when three different lineages of the virus predominated in the UK.
The study involved the collection of data on the nationwide volume of SARS-CoV-2 testing, number of daily deaths and hospitalizations related to COVID-19, the total number of vaccinations, and the number of new daily cases during three time periods, 9th to 15th January 2021, 17th to 25th June 2021, and 25th to 31st December 2021. These three time periods correspond to the three different waves of SARS-CoV-2 brought about by three different variants.
Data on the prevalence of SARS-CoV-2 lineages were also collected. Finally, the different endpoints were compared among the three time periods.
The results indicated that during 9th to 15th January 2021 the Alpha variant was predominant, during 17th to 25th June 2021 the Delta variant was predominant, and during 25th to 31st December 2021, the Omicron variant was predominant. Also, the total vaccinations were reported to have increased during the study period.
The positivity rate during the Alpha period was reported to be 10.7 percent, during the Delta period it was 1.7 percent, and during the Omicron period, it was 11.7 percent. The COVID-19 related hospitalizations decreased by 78 percent from Alpha to Delta, by 83 percent from Alpha to Omicron, and by 22 percent from the Delta to Omicron periods. Similarly, the COVID-19 related deaths also decreased by 93 percent from Alpha to Delta, by 95 percent from Alpha to Omicron, and by 24 percent from Delta and Omicron periods.
The current study, therefore, demonstrates that both increases in population immunity and change in intrinsic factors of the virus might have contributed to the current scenario of the pandemic.
It can be concluded that a path towards SARS-CoV-2 becoming an endemic may have started occurring.
However widespread boosters and vaccination, as well as physical preventive measures, must still be implemented especially by the developing countries to prevent further mutation of SARS-CoV-2 and the emergence of variants.
This study is a preliminary scientific report that has not yet been peer-reviewed and, therefore, should not be regarded as conclusive, guide clinical practice/health-related behavior, or treated as established information.