A Northwell Health registered nurse administers a COVID-19 vaccine shot...

A Northwell Health registered nurse administers a COVID-19 vaccine shot in Westbury. Credit: Debbie Egan-Chin

Developing a vaccine typically takes 10 to 15 years. But faced with a once-in-a-century pandemic — with at least 115 million coronavirus infections, 2.56 million deaths and a global economy paralyzed — pharmaceutical researchers have pioneered vaccines in record time.

Shots approved for use in the United States all use new technology. And so far, none of the vaccines is for children. But there is more research — and likely more vaccine versions — to come that could bring more options and lower age limits so kids can get inoculated against the coronavirus.

Here's what you need to know:

In addition to the three vaccines approved in the U.S., are there more still under development?

Yes. Among those in the pipeline: one by the firm Novavax, which would be a two-shot regimen that injects a synthesized and slightly modified version of the spike protein — spikes, or "coronas," are the way the virus attacks the immune system — using a commonplace insect virus. In the vaccine are DNA instructions to make the coronavirus protein, according to the Wall Street Journal.

There’s also the Oxford-AstraZeneca vaccine, which is in use in parts of Europe but not yet approved in the U.S. Other nations have developed their own vaccines, including China, where the virus began, and Russia, which has the Sputnik V vaccine.

How long until new vaccines are available for public use in the U.S.?

The Wall Street Journal reported that the U.S. Food and Drug Administration likely wants to review data from a late-stage trial, which began in December in Mexico and the U.S., of the Novavax vaccine before considering it for approval. Results aren’t expected until spring.

In addition, there are about 60 million doses of the Oxford-AstraZeneca vaccine in the U.S. that are ready to launch once approved, according to CBS News.

Have some attempts to develop new vaccines failed?

Yes. Merck, for instance, dropped out of its development completely: In January, the company cited insufficient immune response in its vaccine trials, according to USA Today. But earlier this month the company announced that it would help make rival Johnson & Johnson’s vaccine, an arrangement negotiated with the help of President Joe Biden's administration, National Public Radio reported.

Who’s paying for these vaccines to be developed?

In most cases, the taxpayer is footing at least part of the bill. Operation Warp Speed, the Trump-era public-private partnership with a budget of more than $18 billion to help turbocharge vaccine development, has funded about half a dozen candidates. They include the Moderna and Johnson & Johnson vaccines, two of America’s three approved vaccines. (Pfizer-BioNTech did not take Operation Warp Speed funding).

The earliest vaccines aren’t for children. Are there plans for vaccines for them?

The Pfizer-BioNTech vaccine is for those 16 and older. It’s being tested on kids 12 to 15, Yale's medical school reported last month. The Moderna vaccine is for people 18 and older, with tests underway for those 12 to 17. Johnson & Johnson has not tested its vaccine on those under 18, but expects to start.

The BBC reported in February that the Oxford-AstraZeneca coronavirus vaccine would be tested later in the month to study whether the shots elicit a strong response in children between 6 and 17. That test will be on about 240 volunteers, the BBC reported.

When will there be enough vaccines for every American adult?

On March 2, Biden announced that the country was "on track to have enough vaccine supply for every adult in America by the end of May," accelerating the previously announced deadline of July.

How will the vaccines handle the various variants emerging from places like South Africa, the United Kingdom and Brazil?

Moderna has said it’s waiting on government regulators before starting a trial of a variant-modified version of its vaccine, and Pfizer-BioNTech and Oxford-AstraZeneca are reportedly considering doing an update of their vaccines to target new variants, according to the British Medical Association's trade journal.