An older adult receives a COVID-19 vaccine at a temporary vaccination site on Dec. 7 in Chongqing, China. Concerns about effectiveness and safety have led to uncertainty about the COVID vaccine, notably among older citizens, whose vaccination rate is relatively low. He Penglei/China News Service via Getty Images hide caption
Bivalent COVID-19 vaccines are readied for use at a clinic in Richmond, Va., Nov. 2022. Just 15% of eligible Americans have gotten the most recent booster shot, according to the CDC. Steve Helber/AP hide caption
Travelers at Shanghai Hongqiao Railway Station in Shanghai, China on Dec. 12. China's public health officials say up to 800 million people could be infected with the coronavirus over the next few months. Qilai Shen/Bloomberg via Getty Images hide caption
The new COVID boosters rolling out this month represent a shift in strategy, said White House COVID-19 Response Coordinator Dr. Ashish Jha during a press briefing. The goal now will likely be to roll out new boosters annually. Anna Moneymaker/Getty Images hide caption
Vials of the newly reformulated COVID-19 vaccine booster are being readied by Pfizer for distribution now that the Food and Drug Administration has authorized the shots for people 12 and older. Pfizer Inc. hide caption
A single-use syringe awaits to be filled with the Moderna COVID-19 vaccine. Moderna has sued rival drugmakers for patent infringement. Rogelio V. Solis/AP hide caption
Patricia Neves (left) and Ana Paula Ano Bom helped launch a global project to revolutionize access to mRNA technology. Ian Cheibub for NPR hide caption
A kidney dish with syringes containing the Novavax COVID-19 vaccine sits in a refrigerator ready for use in February at a vaccination center in Prisdorf, Germany. Georg Wendt/AP hide caption
A child receives the Pfizer BioNTech COVID-19 vaccine at the Fairfax County Government Center in Annandale, Va., in November 2021. A committee of advisers to the Food and Drug Administration recommended Wednesday that the agency expand authorization of COVID-19 vaccines to children as young as 6-months-old. Chip Somodevilla/Getty Images hide caption
A case of COVID-19 brought 12-year-old Harry Nelson to the emergency room in Syracuse, N.Y., where cases are surging, His mother, photographer Paula Nelson, says he first had mild symptoms — just a headache — but later ran a high fever and began vomiting, which meant he couldn't keep down fever-relief meds. At the ER, he needed saline to rehydrate, Tylenol for his fever and meds to stop vomiting. Paula Nelson for NPR hide caption
Rosy, 6, gives COVID tests and vaccines to her stuffed animals. She herself has been exposed to SARS-CoV-2, the coronavirus that causes COVID-19, multiple times and never tested positive. What's her secret? Michaeleen Doucleff/NPR hide caption
Young women wait to get vaccinated by Namra, a 21-year-old health worker who's part of a national door-to-door vaccination effort in the informal Hindubasti settlement in Karachi. Diaa Hadid/NPR hide caption
A health worker in Mexico City prepares a Sputnik V dose during a mass vaccination effort against COVID-19. A new study in Mexico shows that non-mRNA vaccines like the Russian version can be as effective as mRNA vaccines like Pfizer if the patient has previously been infected with SARS-CoV-2. Luis Barron/Eyepix Group/Barcroft Media via Getty Images hide caption
A Cuban industrial complex prepares to start production of one of the country's newly developed COVID vaccines. Yander Zamora/Pool/AFP via Getty Images hide caption