Then came the Delta variant. Despite keeping their countries largely sealed off, the virus found its way in. And when it did, it spread quickly. In the summer, South Korea battled its worst wave of infections; hospitals in Indonesia ran out of oxygen and beds; and in Thailand, health care workers had to turn away patients.
With cases surging, countries quickly shifted their vaccination approach.
Sydney, Australia, announced a lockdown in June after an unvaccinated limousine driver caught the Delta variant from an American aircrew. Then, Prime Minister Scott Morrison, who had previously said vaccination “was not a race,” called in July on Australians to “go for gold” in the country’s inoculation drive.
What to Know About Covid-19 Booster Shots
The F.D.A. has authorized booster shots for millions of recipients of the Pfizer-BioNTech, Moderna and Johnson & Johnson vaccines. Pfizer and Moderna recipients who are eligible for a booster include people 65 and older, and younger adults at high risk of severe Covid-19 because of medical conditions or where they work. Eligible Pfizer and Moderna recipients can get a booster at least six months after their second dose. All Johnson & Johnson recipients will be eligible for a second shot at least two months after the first.
Yes. The F.D.A. has updated its authorizations to allow medical providers to boost people with a different vaccine than the one they initially received, a strategy known as “mix and match.” Whether you received Moderna, Johnson & Johnson or Pfizer-BioNTech, you may receive a booster of any other vaccine. Regulators have not recommended any one vaccine over another as a booster. They have also remained silent on whether it is preferable to stick with the same vaccine when possible.
The C.D.C. has said the conditions that qualify a person for a booster shot include: hypertension and heart disease; diabetes or obesity; cancer or blood disorders; weakened immune system; chronic lung, kidney or liver disease; dementia and certain disabilities. Pregnant women and current and former smokers are also eligible.
The F.D.A. authorized boosters for workers whose jobs put them at high risk of exposure to potentially infectious people. The C.D.C. says that group includes: emergency medical workers; education workers; food and agriculture workers; manufacturing workers; corrections workers; U.S. Postal Service workers; public transit workers; grocery store workers.
Yes. The C.D.C. says the Covid vaccine may be administered without regard to the timing of other vaccines, and many pharmacy sites are allowing people to schedule a flu shot at the same time as a booster dose.
He moved to overcome a supply shortage, compounded by the slow regulatory approval. In August, Australia bought one million Pfizer doses from Poland; this month, Mr. Morrison announced a purchase of a million Moderna shots from Europe.
When the Delta outbreak emerged, fewer than 25 percent of Australians over the age of 16 had received a single shot. In the state of New South Wales, which includes Sydney, 86 percent of the adult population has now received a first dose, and 62 percent of adults are fully vaccinated. The country expects to fully inoculate 80 percent of its population over the age of 16 by early November.
“There was great community leadership — there were people from across the political divide who came out to support vaccination,” said Greg Dore, an infectious-disease expert at the University of New South Wales. “It really helped us turn around a level of hesitancy that was there.”
Many governments have used incentives to encourage inoculations.
In South Korea, the authorities eased restrictions in August on private gatherings for fully vaccinated people, allowing them to meet in larger groups while maintaining stricter curbs for others. Singapore, which has fully vaccinated 82 percent of its population, previously announced similar measures.
Researchers there have also analyzed the pockets of people who refuse to be inoculated and are trying to persuade them.