COVID cases are starting to rise again, and a new variant of the Omicron lineage called EG.5 has emerged as the most frequent cause of infection. It is similar enough to previous variants that the monovalent mRNA vaccines with only Omicron-like sequences should be effective when they are available. Both Moderna and Pfizer-BioNTech submitted applications for approval to the FDA in late June just a few days after a 21-member advisory panel unanimously recommended a monovalent formulation for this fall. FDA approval is expected in the coming weeks (watch for an update on the Sandpiper website).
It is likely that the current bivalent vaccine, which is a mixture of sequences from the original Wuhan strain and the more recent Omicron variants, will be retired by the FDA. Because most people who got this bivalent booster has already received two shots of the original Wuhan-strain vaccine, their immune system was primed to respond better to the Wuhan component than the Omicron component, and that is what transpired. Using a monovalent vaccine with only Omicron sequences will avoid this problem, and also take advantage of the priming effect of the Omicron component of the bivalent vaccine. This assumes that most people actually got the bivalent booster, but only 39% of adults older than 65 were reported to have received the shot ((Vaccines (Basel). 2023 May; 11(5): 906)).
COVID is here to stay. Be careful, particularly with large, indoor gatherings, and get the new booster shot as soon as it is available. Get your annual flu shot early too. And 39% is a terrible number for vaccine uptake in a vulnerable population; let’s make it 100% in Del Mar.