Jane Greenhalgh

Updated November 17, 2021 at 6:19 PM ET

People 18 or older who are already considered fully vaccinated could soon be eligible to get a Pfizer-BioNTech or Moderna COVID-19 vaccine booster shot. Moderna asked for that authorization on Wednesday, one day after Pfizer made its application.

A third dose of the Moderna vaccine — given six months after the initial two doses — significantly boosts immunity, according to data the company submitted to the Food and Drug Administration on Wednesday.

People with compromised immune systems who already got two doses of the Pfizer or Moderna vaccines can now get a third shot to boost their protection from COVID-19.

This week's decision by federal health agencies is welcome news to many patients and their doctors who have been calling for this for months.

The Food and Drug Administration is authorizing an additional dose of a COVID-19 vaccine for certain people with weakened immune systems caused either by disease, medical treatments or organ transplants.

The move comes after studies have shown these people may not have sufficient immunity to head off the more serious complications of COVID-19 after the standard vaccine regimen.

An internal slide presentation from the Centers for Disease Control and Prevention dated Thursday gives new details on how dangerous the delta variant really is.

One chart shows that it could be as contagious as chickenpox, which is one of the more transmissible viruses out there. It spreads more easily than the common cold, the 1918 flu and smallpox.

Life expectancy in the United States declined by a year and a half in 2020, according to the Centers for Disease Control and Prevention, which says the coronavirus is largely to blame.

COVID-19 contributed to 74% of the decline in life expectancy from 78.8 years in 2019 to 77.3 years in 2020, according to the CDC's National Center for Health Statistics.

The highly contagious delta variant now accounts for more than 51% of COVID-19 cases in the U.S., according to new estimates released by the Centers for Disease Control and Prevention. The variant, also known as B.1.617.2, was first detected in India and is spreading quickly across the globe.

And in parts of the U.S., the delta strain accounts for more than 80% of new infections, including some Midwestern states such as Missouri, Kansas and Iowa.

The Delta variant, which was first detected in India, now accounts for more than 6% of all infections in the United States, according to the Centers for Disease Control and Prevention. And this highly transmissible variant may be responsible for more than 18% of cases in some Western U.S. states.

The Food and Drug Administration says it's now OK to store the Pfizer COVID-19 vaccine at normal refrigerator temperatures for up to a month. This is much longer than was previously allowed under the FDA's emergency authorization and will make storage and distribution of the vaccine easier.

Since the pandemic began, pregnant people have faced a difficult choice: to vaccinate or not to vaccinate.

The risk of severe disease or even death from COVID-19 — while small — is higher during pregnancy. More than 82,000 coronavirus infections among pregnant individuals and 90 maternal deaths from the disease have been reported in the U.S. as of last month.

It's been more than a year since I've seen my mother. Like many families, we live a fair distance apart and the pandemic has put a stop to our visits. I was supposed to visit last April to celebrate her 90th birthday, but instead we shared a toast over the phone and tightly crossed our fingers that by summer things would be better. They weren't.

It's supposed to be the happiest time of the year, but this year it doesn't really feel like it. With many of us hunkered down at home, some having lost jobs, others having lost friends and family members to COVID-19 or other illnesses, it's tempting to give this holiday season a miss.

But it's important to find joy and meaning in the midst of this dark winter — and carrying on with favorite holiday traditions can help. NPR checked in with medical researchers to figure out how risky our favorite customs are, and highlight ways we can all celebrate more safely.

It has become the battle cry of public health officials around the world: "Wear a mask to slow the spread." Friday, the U.S. Centers for Disease Control and Prevention released new evidence supporting this advice.

Researchers analyzed coronavirus infection rates in Kansas following a statewide mask mandate. They found that counties that chose to enforce the mandate saw their cases decrease. Counties that chose to opt out saw their cases continue to rise.

The vast majority of children dying from COVID-19 are Hispanic, Black or Native American, according to a new report from the Centers for Disease Control and Prevention.

Researchers analyzed the number of coronavirus cases and deaths among people under the age of 21 that were reported to the CDC between Feb. 12 and July 31 of this year. They found more than 390,000 cases and 121 deaths.

As schools across the country grapple with bringing kids back into the classroom, parents — and teachers — are worried about safety. We asked pediatricians, infectious disease specialists and education experts for help evaluating school district plans.

What we learned: There's no such thing as zero risk, but certain practices can lower the risk of an outbreak at school and keep kids, teachers and families safer.

One of the hardest things during this pandemic — for kids and adult children — has been staying away from their parents and grandparents.

People 65 years and older are at higher risk for getting a severe case of COVID-19, according to the Centers for Disease Control and Prevention. And about 80% of deaths in the U.S. from COVID-19 have been in people older than 65.

A large study of the drug hydroxychloroquine has been retracted by three of its authors.

The paper, published in the journal the Lancet last month, concluded that hydroxychloroquine, taken either alone or with an antibiotic, to treat patients with COVID-19 was of no benefit and actually increased a patient's risk of dying.

President Trump is repeating his claim that the United States is doing more testing for the coronavirus than any other country.

"We have more cases because we're doing far more testing than anybody in the world," the president said in a White House briefing on Sunday.

The U.S has ramped up testing, but still lags other countries like Italy and South Korea, when it comes to testing on a per capita basis.

If there's one thing we're grateful for on Shots, it's our passionate, engaged audience. Our stories often prompt a lively response from readers and people who hear us on the radio. This was definitely the case with Monday's look at the use of permethrin-treated clothing to prevent tick bites, which can cause a lot of nasty diseases.

It's an unusually bad wild fire season in the West, and for weeks people across the region have been breathing air thick with smoke.

"There's smoke from Canada, smoke from Idaho, smoke from California and Montana. There's smoke everywhere," says Greg Svelund, a spokesman for Oregon's Department of Environmental Quality.

With more states legalizing recreational marijuana, parents are facing the question of whether they should smoke pot around their children.

"I have never smoked and would never smoke around my child," says one mother who lives in San Francisco. California is one of eight states that allows recreational marijuana use for adults 21 and older.