The Centers for Disease Control and Prevention (CDC) recommended American adults that have not yet been vaccinated for COVID-19 consider the Novavax vaccine. Between 26 million and 37 million adults still haven’t had a single dose.

“Novavax’s COVID-19 vaccine, which will be available in the coming weeks, is an important tool in the pandemic and provides a more familiar type of COVID-19 vaccine technology for adults,” the CDC said Tuesday. “Having multiple types of vaccines offers more options and flexibility for the public, jurisdictions, and vaccine providers.”

Novavax’s vaccine is different from the mRNA vaccines offered by Pfizer and Moderna. While the mRNA vaccines deliver genetic instructions for the body to make copies of the spike protein, the Novavax vaccine injects copies of the spike protein that are grown in a lab and packaged into nanoparticles that to the immune system resemble a virus.

“If you have been waiting for a COVID-19 vaccine built on a different technology than those previously available, now is the time to join the millions of Americans who have been vaccinated,” CDC Director Rochelle Walensky said in a statement on the Novavax announcement. “With COVID-19 cases on the rise again across parts of the country, vaccination is critical to help protect against the complications of severe COVID-19 disease.”

None of the four vaccines now on the market fully prevent COVID-19 infection; they only reduce the chance of infection and lessen symptoms.

Another way of taking a vaccine could keep the virus away entirely, according to scientists. The research on nasal vaccines is looking ‘promising’, according to scientists involved in clinical trials. Nasal vaccines deliver a boost of immunity right where the virus enters the body.

These vaccines “concentrate the immune protection in the upper airway,” Dr. Anthony Fauci, the White House’s chief medical adviser, told NBC News in an interview. In doing so, the “antibodies that are trying to protect you from having the virus enter your body, are right there on the front lines protecting you.”

There is still much needed research to be done on nasal vaccines. Dr. Fauci has said the soonest they could become available would be in a few years.

In the meantime, health officials are doing what they can to prevent further spread of COVID-19 as hospitalizations have increased 17% nationwide since the start of July. Health officials are confident a fourth vaccine now on the market has the potential to help.

The Associated Press contributed to this report.