Immune memory to SARS-CoV-2 Omicron BA.1 breakthrough infections: To change the vaccine or not?
MC van Zelm, Sci Immunology, June 2, 2022
The emergence of variants provides a challenge to the current vaccines and vaccination strategies because there is a risk of decline in vaccine efficacy as the number of mutations within Spike epitopes rises. Potentially, vaccine strain updates will be required in a manner similar to the annual influenza program. However, decision-making should be based on both real world and experimental evidence. Recent data demonstrate that the current COVID-19 vaccines reduce the risk of infection, but this protection is incomplete and wanes rapidly within weeks after the second dose (3). In contrast, the initial double-dose mRNA vaccination is highly protective against severe disease for >5 months from Wuhan and Delta variants. This efficacy is lower and lasts shorter against Omicron infection, but is highly boosted by third dose vaccination
Variant-specific symptoms of COVID-19 among 1,542,510 people in England
M Whitaker et al, MEDRXIV, May 23, 2022
We show changing symptom profiles associated with the different variants over that period, with lower reporting of loss of sense of smell and taste for Omicron compared to previous variants, and higher reporting of cold-like and influenza-like symptoms, controlling for vaccination status. Contrary to the perception that recent variants have become successively milder, Omicron BA.2 was associated with reporting more symptoms, with greater disruption to daily activities, than BA.1.
The clinical progress of mRNA vaccines and immunotherapies
AJ Barbier et al, Nature Biotechnology, May 9, 2022
Most clinical applications of mRNA to date have focused on vaccines for infectious disease and cancer for which low doses, low protein expression and local delivery can be effective because of the inherent immunostimulatory properties of some mRNA species and formulations. In addition, work on mRNA-encoded protein or cellular immunotherapies has also begun, for which minimal immune stimulation, high protein expression in target cells and tissues, and the need for repeated administration have led to additional manufacturing and formulation challenges for clinical translation. Building on this momentum, the past year has seen clinical progress with second-generation coronavirus disease 2019 (COVID-19) vaccines, Omicron-specific boosters and vaccines against seasonal influenza, Epstein–Barr virus, human immunodeficiency virus (HIV) and cancer.
Are COVID surges becoming more predictable? New Omicron variants offer a hint
E Callaway, Nature, May 6, 2022
Omicron relatives called BA.4 and BA.5 are behind a fresh wave of COVID-19 in South Africa, and could be signs of a more predictable future for SARS-CoV-2.
If SARS-CoV-2 continues along this path, its evolution could come to resemble that of other respiratory infections, such as influenza. In this scenario, immune-evading mutations in circulating variants, such as Omicron, could combine with dips in population-wide immunity to become the key drivers of periodic waves of infection.