Why vaccinating the world against COVID-19 is a monumental undertaking.

COVID-19 vaccines were found to cut risk of heart failure by up to 55% and blood clots by up to 78% following COVID infection, according to a new study.

Newly released survey data from the CDC shows 36 million American adults, about 13.9% of the U.S. adult population, has received the updated COVID vaccine.

Older adults who got a COVID booster and a high-dose version of the flu vaccine together may have an increased risk of stroke, according to a new FDA-funded study.

Moderna announced the first participant has been dosed in the company's phase 3 clinical trial of its combination flu and COVID vaccine.

The latest poll conducted by the KFF COVID-19 Vaccine Monitor found that nearly half of all adults in the U.S. plan to get the newly recommended COVID-19 vaccine.

Immunity wanes after anywhere from 3-6 months, experts say.

Florida's former surgeon general is speaking out against the DeSantis administration advising against updated COVID shots for people under 65.

Florida Gov. Ron DeSantis is advising against the use of the new COVID-19 booster for people under the age of 65, even as infections tick upward in the U.S.

The latest, updated COVID-19 vaccines should soon be available to everyone and offered largely free of cost, according to the CDC.

"We'd all wish for COVID to be in the rearview mirror but, unfortunately, it's still here," CDC Director Mandy Cohen told ABC News.

The CDC recommended that all Americans aged 6 months and older receive the new COVID booster that targets currently circulating variants.

Despite the continued rise, the most recent week was the smallest percent increase in the past 2 months, according to the CDC data.

The upcoming COVID-19 booster is expected as early as next week.

The updated COVID vaccine should be released in mid September.

Over $1.4 billion has been awarded to clinical trials for COVID-19 vaccines, the development of a new monoclonal antibody, and new vaccines and therapeutic technologies.

Despite the rising number of COVID cases and hospitalizations, experts said most people should wait for the updated boosters to be released before getting another shot.

A new study found that the original COVID-19 vaccines saw their effectiveness decline against infection with the omicron variant to less than 20%.

An upstate New York midwifery is facing federal charges after allegedly distributing thousands of fake COVID-19 vaccination cards and destroying vaccine vials.

The FDA authorized a second omicron-targeted bivalent COVID-19 booster vaccine for people over 65 or who are immunocompromised.

Here's what the FDA and CDC wrote in a letter to Florida Surgeon General Joseph Ladapo, whose claims about COVID-19 vaccines are "harmful" to public health.

Moderna has announced it will provide its COVID vaccine for free to people without insurance, even after government money dries up.

One of the largest municipal worker COVID-19 vaccine mandates is ending this week as 96% of New York City workers have received their shots, Mayor Eric Adams said.

The FDA outlined an approach to yearly COVID vaccines, like the flu shot.

According to briefing documents, the FDA is proposing a new COVID vaccine strategy: that most Americans receive one shot per year, similar to the flu vaccine.

More than one year after COVID-19 vaccines authorized for elementary school-aged children, a mountain of data supports they are safe and effective.

A plastic surgeon, his neighbor and two of his employees are alleged to have ran a fake vaccination records scheme through the doctor's Salt Lake City-area practice.

Bernie Sanders, the incoming chair of the Senate committee focused on health, called out Moderna in a letter for looking at a spike of its COVID-19 vaccine prices

A sharp increase in COVID-19 cases and hospitalizations since the Thanksgiving wasn't a surprise, Dr. Ashish Jha said Sunday, urging people to get the new vaccine

The most common reason vaccinated people aren't getting a COVID booster is that they don't think they need one, a survey found.

Dr. Jha said getting a bivalent booster is the "most important thing you can do to make sure immunity is up to date."

The U.S. Food and Drug Administration authorized bivalent COVID-19 boosters for children between ages 6 months and 4 years Thursday.

The updated COVID bivalent booster that targets multiple newer strains of the virus, will likely be available early next week for the youngest children

The White House called repealing the mandate a "mistake."

Health officials are making another urgent push to encourage flu and COVID vaccinations, as multiple respiratory viruses swirl around the country.

The White House's Dr. Ashish Jha said Sunday that updated COVID-19 vaccinations will help people "move on" from the pandemic

"If folks get their updated vaccines and they get treated if they have a breakthrough infection, we can prevent essentially every COVID death in America," Dr. Jha said.

Moderna says it plans to seek emergency use authorization from the U.S. Food and Drug Administration for its COVID-19 vaccine in children under age 6.

Mayor Eric Adams said he wanted to "level the playing field," and dropped the proof of vaccine requirement for New York City's athletes and entertainers.

Pfizer and Moderna asked the FDA last week to authorize another booster dose.