Pandemic fatigue makes the case for boosters a harder sell

Some nations are already looking to a fourth vaccine dose to help contend with a huge Omicron-driven spike in Covid-19 cases, but early signs suggest repeat vaccination may be a hard sell as beleaguered populations enter their third pandemic year.

Uptake of the first round of boosters in recent months –a third shot for most – has lagged initial vaccinations.

Disease experts say that rapidly shifting public health messaging in the face of a quickly-mutating virus has bred confusion and mistrust...