Bivalent Boosters against Severe Omicron Infection.

To the Editor: Lin and colleagues (Feb. 23 issue)(1) report the vaccine effectiveness of bivalent Covid-19 vaccines in a large cohort of more than 6 million persons. The authors conclude that bivalent boosters provided substantial additional protection in persons who had previously been vaccinated. As reported lately, the cost of a single dose of bivalent vaccine is expected to rise to $120 (U.S. dollars).(2) On the basis of the reported vaccine efficacies,(3) we estimated the number needed to vaccinate and the associated cost to avoid one severe Covid-19 outcome (hospitalization or death) or one death (Table 1). Because most Covid-19-related . . .