In fact, since the advent of Omicron, multiple studies have demonstrated that Omicron is just not very good at infecting lung tissue. As such, given the ability of BQ.1 and BQ.1.1 to evade neutralizing antibodies, we expect an increase in country-level hospitalization numbers this winter due to incidental positives, but we should be reassured that the vast majority will not be for severe COVID illness.

But many hospitals and health care systems have been reluctant to relinquish this outdated practice. The CDC in fact in September advised that hospitals could stop routine pre-admission testing for COVID. The majority of states and county public health departments still do not delineate COVID-19 hospitalizations between those admitted primarily for COVID vs. By severe COVID, we are referring to patients with viral pneumonia and hypoxia requiring various oxygen-delivery and ventilation systems and strategies, intravenous decatron and other complicated immune-modulating medications, and the involvement of respiratory therapists and multiple medical specialists. We rarely encounter patients with severe COVID in the ED or hospital wards now, in sharp contrast to the winter of 2020. This certainly begs the question: has SARS-COV-2 hit an evolutionary ceiling in the face of our high population immunity? Where have severe COVID-19 patients gone? So, a convergence of rapidly accruing mutations demonstrating immune evasiveness in the lab has not generated a surge in infections or hospitalizations in the real world. BQ.1.1 became dominant in France at the end of October but has not led to a surge in hospitalizations or ICU admissions. share a lagging updated bivalent booster rate for those at higher risk for severe COVID illness (older individuals)-approximately 30% of those 65 years or older in both countries have received the updated booster. Despite these apparent growth advantages, XBB did not lead to a major surge in hospitalizations or deaths in Singapore.Īlthough important to tread carefully when comparing countries, France’s recent experience with BQ.1.1 likely provides insight into how that variant will play out here.

XBB is a descendant of BA.2 but differs by 8 key spike mutations. The XBB variant achieved dominance in Singapore earlier this Fall. But, if such a shift were to happen, our T-cells and memory B-cells will continue to provide robust protection against severe disease from new variants. As long as there is not a dramatic antigenic shift to an entirely new lineage, there are very little new tricks Omicron can throw our way. It’s safe to say a lot of immune systems have “seen” Omicron by this point on top of a vaccination rate of 73% in those 5 and older. By the end of February, that number was 60%-and certainly much higher now at the end of 2022. The most recent summer wave driven by BA.4 and BA.5 did not lead to a significant surge of hospitalizations or deaths in the U.S.īefore the Omicron winter surge a year ago, only 1 in 3 people in the U.S. This antigenic drift, while spawning an alphabet soup of approximately 500 subvariants, has actually generated less and less impactful waves as population level immunity to Omicron grew. But since South African researchers first identified Omicron one year ago, we have seen subvariants exclusively from that lineage. The first two pandemic years were marked by surge after surge driven by variants of entirely new lineages.

Covid antigenic shift