What You Need to Know About the Novavax Vaccine

Updated 8/24/2022

For adults who have yet to be vaccinated for COVID-19, there is a new option that uses a time-tested approach. In July 2022, Novavax became the fourth COVID-19 vaccine authorized for use in the United States, joining the ones from Pfizer, Moderna and Johnson & Johnson.

Dima Dandachi, MD, MPH, an infectious disease specialist at MU Health Care, said Novavax is a good choice for people who have been hesitant to get the Pfizer or Moderna vaccines because they use a new method — messenger RNA (mRNA) that teaches the cells in our body how to create an immune response to the virus that causes COVID-19.

“There’s no data to show the mRNA vaccines are unsafe, but because we don’t have long-term data about them beyond two years, some people are reluctant to use this new vaccine technology,” Dandachi said. “This Novavax vaccine could be appealing to them. Novavax uses a technology that has been used in other vaccines for a long time.”

Novavax is a protein subunit vaccine. That means it uses a protein — in this case, a harmless piece of the COVID-19 spike protein — to alert your immune system to recognize and fight back against the real COVID-19 virus. It also includes an adjuvant, which is a substance that boosts the level of immune response. It is the same approach that has been used for decades in the vaccines for influenza, hepatitis B and HPV.

Novavax is approved only as a primary vaccine series — with two shots given three to eight weeks apart — and is not currently approved as a booster.

Is it effective?

Novavax was tested on more than 30,000 adults beginning in December 2020. MU Health Care participated in the study, enrolling 103 people who got the shots and continue to be monitored to determine the long-term effectiveness and safety of the vaccine.

The study showed Novavax was about 90% effective in preventing COVID infections. That is similar to the efficacy of Moderna (94%) and Pfizer (95%) and better than Johnson & Johnson (66%). But Dandachi said it is hard to fairly compare the vaccines’ efficacy because the studies were done at different times and infection rates have ebbed and flowed throughout the pandemic.

Each of those studies were conducted before the emergence of the omicron variant, which is better at evading vaccines than earlier versions of the virus, but all the vaccines have remained effective at preventing severe symptoms or death from COVID-19.

“The main idea for vaccines is to prevent severe disease, prevent hospitalization and prevent death,” Dandachi said. “Even with omicron’s most-circulating strain, people who are vaccinated are protected from severe disease and death, even though people are still getting sick from COVID.”

Is it safe?

The Novavax vaccine went through the same intense safety testing process as any other vaccine, and it was found to be safe.

Serious side effects after COVID-19 vaccination are rare. Pericarditis (inflammation of the heart lining) and myocarditis (inflammation of the heart muscle) have been reported in people who received the Novavax, Pfizer and Moderna vaccines.

“They have to report all adverse events that are serious,” Dandachi said. “Although there is no clear evidence that these cases are caused by the vaccine, they happened after vaccine administration. But the number was really small — six people among 30,000 in the Novavax study.”

Novavax does not contain potential allergens such as eggs, latex, metals or preservatives. It can cause similar temporary side effects to other vaccines, such as pain and redness at the injection site, muscle aches and fatigue.

“Those side effects mean it’s working to produce a response that we want,” Dandachi said. “These symptoms are mild and disappear after a few days.”