Medical Case Reports

In summer 2025, the Nimbus (NB.1.8.1) and Stratus (XFG) variants were competing for dominance (see previous post  Nimbus and Stratus: Cloudy With a Chance of Covid ). By that point, earlier JN.1-descended variants such as LP.8.1 had already been largely displaced. That competition is now largely settled, with Stratus and its descendants firmly in the lead across most regions. As of early January 2026, Stratus (XFG) and its descendants dominate globally. In the U.S., sequencing and wastewater data show XFG making up 60–70% of cases, and when its sublineages (XFG.14.1, XFG.1, XFG.6) are included, the total reaches ~80% by late December. Nimbus has fallen sharply and now accounts for roughly 5% of sequenced cases. The new variant to watch is BA.3.2 nicknamed “Cicada”. Unlike recent variants that evolved incrementally from JN.1, BA.3.2 represents a larger evolutionary jump. It's a descendant of early Omicron BA.3, a lineage that largely disappeared in 2022. Cicada was designated by WHO...

mRNA vaccination can, in relatively rare cases, trigger a spectrum of immune-mediated cardiac effects ranging from transient myocardial inflammation and biomarker elevation to clinically apparent myocarditis, with fulminant myocarditis representing the most severe but least common manifestation A new Stanford Medicine study sheds light on a long-standing question: why do mRNA-based COVID-19 vaccines could cause myocarditis, particularly in young males? Importantly, the findings also point toward possible ways to reduce this risk without undermining vaccine effectiveness. The researchers identified a two-step immune reaction behind vaccine-associated myocarditis. After vaccination, macrophages (frontline immune cells) release a signaling protein called CXCL10. This, in turn, activates T cells, which produce another inflammatory molecule, interferon-gamma (IFN-γ). Together, these cytokines act as a “tag team,” driving inflammation that can directly injure heart muscle cells and attract a...

From vaccine math to biosafety preprints, recent studies reveal that unreported risks and hidden biases shape our understanding of COVID more than most headlines admit. Remember when getting vaccinated against COVID felt simple? One shot, maybe two, and you were done. Fast forward a few years, and we’ve had first doses, second doses, boosters, updated boosters, and debates about whether you need a booster for your booster . But a recent study crunching UK mortality data says: “Hold up. Maybe more shots aren’t adding as much protection as we think.” Add in your earlier research about antibody changes after repeated doses , and suddenly the COVID vaccine story feels less like “science is settled” and more like “science is a detective novel.” Let’s break it down in plain language. A.J. Oostenbrink’s new preprint looked at COVID and non-COVID death rates in the UK over two years. Instead of assuming COVID deaths rise proportionally with overall health risk, they used a formula: D covi...

As we venture into the end of summer, there’s no denying that COVID-19 is making its move again. Covid waves always follow a seasonal pattern  - two waves per year: winter and summer or fall. So far, the smallest (not in terms of deadliness though, just the number of infected) wave hit during the winter of 2020-2021, while the Omicron surge of 2021-2022 took the crown for the biggest wave. Last year was a bit of a wild card, with the summer/fall wave being slightly taller than the winter one. However, so far, this year hasn’t had much of a summer/fall wave (yet) but hold on tight because things are looking a little more intense as we approach the winter. From December 2024 to February 2025, we experienced what could be called "Wave X," a quieter episode compared to earlier waves, but it still made its presence felt. Fast forward to August 2025, and we’re beginning to see the rise of the next wave—a little like what we saw in 2023 and 2024. According to Mike Hoerger’s post on ...

Post-Vaccination IgG4 and IgG2 Class Switching is linked to Increased Risk of SARS-CoV-2 Infections A new study published in Infectious Disease Practice has revealed a concerning correlation between the class switching of antibodies after COVID-19 mRNA booster vaccinations and a heightened risk of breakthrough infections. Specifically, the study found that elevated levels of IgG4 and IgG2 antibodies, which increase significantly following the third mRNA dose, are linked to an increased risk of symptomatic SARS-CoV-2 infections.  The study followed a longitudinal cohort of 83 healthcare workers who received three vaccine doses, with an additional 66 participants analyzed at a specific timepoint (T9, May 2022), four months after the first booster. Conducted in Spain, the research tracked immune responses over nearly three years, revealing that the proportion of non-cytophilic antibodies (IgG4 and IgG2) increased relative to cytophilic subclasses (IgG1 and IgG3) after the booster. Th...

From wild type to Alpha (B.1.1.7), Delta (B.1.617.2), Omicron BA.1, BA.2, BA.5,  BQ.1/BA.2.75,  XBB, JN.1, FLiRT variants and now XEC and LP.8.1 (BA.2.86.1), the virus keeps evolving, continuously demonstrating its ability to adapt and mutate.  As we enter the tenth wave of COVID-19 in the U.S, the XEC variant has emerged as the dominant strain - in line with expectations. It could be " a weak leading variant "  but will it be a " very muted holiday wave relative to all prior years , due to weak evolution and large summer numbers"?  Until recently in the US KP.3.1.1 was dominating wastewater samples and accounting for a considerable proportion of infections. Looking at the growth advantages of variants over the last year led to predictions of significantly lower impact  than JN.1 that "XEC should only modestly bump what the winter wave would be without any new variant" by one of COVID forecasters . But other variants are also gaining traction. The off...