Mix-and-match booster shots shown more effective against Omicron strainA letter yesterday in the New England Journal of Medicine (NEJM) from Centers for Disease Control and Prevention scientists shows homologous (same-vaccine) boosting for Johnson & Johnson (J&J) vaccine recipients was significantly less effective than mix-and-match booster doses when the Omicron strain was predominant in the United States.Approximately 18 million Americans received the one-dose J&J vaccine as their primary COVID-19 vaccine.
The study tracked COVID-19 cases among J&J recipients with no booster, a J&J booster, an mRNA booster, and adults who received three doses of mRNA vaccine (a primary series plus a booster).The investigators collected data from Jan 2 to Mar 23, 2022, from the Increasing Community Access to Testing (ICATT) platform, which reported results from drive-through testing sites, and included adults who had reported vaccination status.
The authors found vaccine effectiveness was highest for the regimens that included a booster dose of an mRNA vaccine and was lowest for those who received a single J&J shot.Single-dose J&J efficacy was 17.8% (95% confidence interval [CI], 4.3% to 29.5%) compared to no vaccination from 14 days to 1 month after the shot, and 8.4% (95% CI, 1.5 to 14.8) from 2 to 4 months since receipt of the vaccine.For recipients who received a J&J booster dose after a J&J primary vaccine, efficacy was 27.9% (95% CI, 18.3% to 36.5%) 14 days to 1 month after boost, and 29.2% (95% CI, 23.1% to 34.8%) 2 to 4 months after boost.
In adults who received J&J plus an mRNA booster, efficacy was 61.3% (95% CI, 58.4% to 64.0%) and 54.3% (95% CI, 52.2% to 56.3%), similar to rates seen in those with three mRNA doses: 68.9%