Covid Update – New Variants; Vaccine Side Effects?

Two new COVID virus variants, KP.2 and JN.1.7 (renamed KP.1.1), have replaced their parental strain JN.1 as the most prevalent virus strains as of the May 11th CDC report. The two new variants have been nicknamed FLiRT based on the single letter amino acid code for the changes from the JN.1 sequence. The good news is that the FLiRT variants are closely related to JN.1, so that a new mRNA vaccine based in the JN.1 sequence expected this fall should be protective against hospitalization or death. At this time, there is no evidence that the FLiRT variants cause more severe disease, only that they are more transmissible than JN.1.


For those of us over 65, this news means another COVID vaccine booster shot this fall, along with vaccine shots for flu, RSV (respiratory syncytial virus), and pneumococcal pneumonia (PneumoVax 23). Starting to feel like a pincushion?


I have heard recent concerns about the potential side effects of COVID vaccines. Side effects do occur with all vaccines, but they are exceedingly rare with the COVID vaccines, particularly those that use mRNA (Pfizer/BioNTek and Moderna). The CDC reports that more severe side effects occur in 4-5 individuals/million (0.4-0.5/100,000) vaccinees. Myocarditis (inflammation of the heart) after booster shots is a rare complication in young men, but it is exceedingly rare in other age groups.


As summarized in Table 1, COVID vaccination with a booster shot is highly protective against death in all adult age groups, even those over 80 who often have other health issues and a poor immune response to any vaccine. The risk of dying from COVID is much higher than the risk of any significant adverse event in all age groups, particularly in those over 65 years of age.


TABLE 1. Average weekly COVID deaths per 100,000 in the U.S. (4/2022-4/2023)

RELATIVE RISK = Risk of death in UNVACCINATED versus BOOSTED per AGE group; data from the CDC and NY Times.