States where parents have hesitated to inoculate their children against Covid-19 are now ordering fewer vaccine doses for children under 5 than others.
New Omicron variants are prompting vaccine-makers to tweak their formulas. Experts weigh in on who needs additional boosters and whether to hold off for the revised shots due in the fall.
Pfizer and its German partner, BioNTech, said Monday that an early analysis showed their three-dose coronavirus vaccine regimen triggered a strong immune