Covid-related hospitalizations in the United States have increased from a rough daily average of 45,000 in early November 2021 to about 58,000 now. These are Delta-driven. Omicron is not yet impacting US hospitalizations. The January 2021 peak for US covid hospitalizations (see chart below) was just over 125,000. On December 8, 2020 there were just over 102,000 Americans hospitalized with covid.
The rapid increase in current South Africa covid case counts is being caused by omicron. Hospitalizations are beginning to increase too. Delta and omicron are each tough enough alone, a combined effect would not be welcome anywhere by anyone.
Usually reliable sources had told me that meaningful virologic analysis of severity (aka virulence) would be available by now. Instead I am seeing early (small but rigorous) virologic analysis of vaccine effectiveness. Some aspects of severity can be inferred, but are less than definitive.
A multinational team organized by the Africa Health Research Institute has released a pre-print reporting on results of an analysis of how antibody immunity fostered by the Pfizer vaccine is affected by omicron. According to this analysis, omicron is much more successful at evading vaccine-induced immunity that prior variants. But the study also found, “Previous infection, followed by vaccination or booster is likely to increase the neutralization level and likely confer protection from severe disease in Omicron infection.” (More)
A separate study by the Karolinska Institute and its international partners released yesterday also found diminished immunity to omicron in vaccinated persons, but the reduced protection was less pronounced than the AHRI findings and “highly variable.” The researchers also emphasize, “Almost all serum samples evaluated retained some neutralization activity against the Omicron variant.” (More)
Just before 0700 Eastern Time this morning Pfizer announced, “Preliminary laboratory studies demonstrate that three doses of the Pfizer-BioNTech COVID-19 Vaccine neutralize the Omicron variant (B.1.1.529 lineage) while two doses show significantly reduced neutralization titers.” This is coherent with the AHRI and Karolinska findings. Much more to come.