The Centers for Disease Control and Prevention on Tuesday signed off on Novavax’s two-dose Covid-19 vaccine as a primary series for adults, offering people who are unvaccinated a choice to receive a vaccine based on conventional technology in use for more than 30 years.
The CDC’s independent advisory committee voted unanimously to recommend the vaccine for people age 18 and older after reviewing the vaccines’ safety and effectiveness during an hours-long public meeting Tuesday. CDC Director Dr. Rochelle Walensky seconded the recommendation later in the evening, the final step in the US authorization process.
The CDC, in a statement, said the vaccine will be available to the public in the coming weeks. The Biden administration has provided 3.2 million doses of the Novavax vaccine so far, according to the Department of Health and Human Services.
The CDC approval ends a two-year journey for Novavax, one of the early entrants in the US race to produce a vaccine to protect against Covid-19. The small Maryland biotech company received $1.8 billion in taxpayer money from Operation Warp Speed, but struggled to establish its manufacturing base and eventually fell behind Pfizer and Moderna.
According to CDC data, Novavax’s vaccine will enter the U.S. at a time when more than three-quarters of American adults, 77%, are already fully vaccinated with Pfizer, Moderna, and to a much lesser extent with Johnson & Johnson vaccines.
Walensky, in a statement, said the Novavax vaccine will provide another option for people who don’t want to get the Pfizer and Moderna vaccines. Somewhere between 26 million and 37 million adults are still unvaccinated in the US, according to CDC data, but it’s unclear how many of those people will choose to get the Novavax vaccine.
“The main target population for Novavax will be the 10% to 13% of those who are unvaccinated,” said Dr. Oliver Brooks, a member of the CDC’s vaccine committee and chief medical officer at Watts HealthCare Corporation in Los Angeles.
“I understand that we’re really focused on that population with the hope that maybe this protein subunit vaccine will change them from being unvaccinated to being vaccinated,” Brooks said.
Effectiveness and safety
Novavax injections were 90% effective in preventing disease overall and 100% effective in preventing severe disease when the alpha variant of Covid was dominant, according to clinical trial data. The company has not released data on the real-world effectiveness of its shots against omicron and its subvariants.
But Novavax’s vaccine appears to produce a strong immune response against omicron and its subvariants, which would suggest that it is effective against the variant. The company’s immune response data against omicron impressed members of the Food and Drug Administration’s vaccine committee last month.
The FDA in a fact sheet for health care providers warned that the Novavax vaccine appears to carry a risk of inflammation of the heart called myocarditis. FDA officials reported four cases of myocarditis and pericarditis — swelling of a membrane surrounding the heart — from clinical trials of Novavax in young adults ages 16 to 28.
The Pfizer and Moderna injections also pose a high risk of myocarditis for teenage boys and young men after the second dose. The CDC has found that Covid infection carries a greater risk of heart inflammation than vaccination with the Pfizer or Moderna vaccines. Myocarditis is usually caused by viral infections.
Different technologies
Novavax’s vaccine uses a different platform than Pfizer’s and Moderna’s vaccines. The Novavax vaccine is based on protein subunit technology in use for more than 30 years, beginning with the first licensed hepatitis B vaccine, according to the CDC. The technology is also used in flu and whooping cough vaccines.
Novavax produces inactive copies of the virus protein by inserting the genetic code into an insect virus that infects moth cells. Yeast copies are harvested and purified from those cells for her vaccine.
The spike protein is the mechanism the virus uses to invade human cells. The yeast copies in the vaccine prepare the body’s immune system to produce antibodies that block the virus from invading human cells. Novavax’s vaccine also has an additional ingredient called an adjuvant derived from the bark of a South American tree to produce a broader immune response to fight the virus.
In contrast, Pfizer and Moderna’s vaccine use messenger RNA technology. Their images send the messenger RNA to human cells, which then produce inactive copies of the yeast protein to generate an immune response to fight the virus. Pfizer and Moderna’s vaccines are the first mRNA vaccines to receive FDA approval.
Novavax shots are also stored at normal refrigerator temperatures, while those from Pfizer and Moderna require subzero cold.
Although the FDA has repeatedly authorized Pfizer and Moderna’s vaccines as safe and effective for every age group in the US, health officials have struggled to convince millions of skeptics to get the shots.
Change of vaccine in autumn
The US is planning to modify vaccines to target the more transmissible BA.4 or BA.5 subvariants of omicron, which are now dominant, ahead of an expected fall vaccination campaign. Covid vaccines are less effective at preventing omicron infection due to multiple variant mutations, but they still generally protect against severe disease.
US health officials believe changing the vaccine formula to target omicron variants as well as the original strain that emerged in Wuhan, China, in 2019 will provide more durable protection against the virus this fall.
Novavax’s vaccine, like every currently licensed Covid vaccine, is based on the original strain of the virus that first appeared in China. Like Pfizer and Moderna, Novavax is developing vaccines that target the omicron variant, but company executives have said it is not clear that they should release an updated vaccine because the company’s current vaccine elicits a broad immune response against the variant.
The CDC and FDA have not approved the mixing and matching of Novavax’s vaccine with Pfizer’s and Moderna’s vaccines as a booster. Novavax has said it plans to ask the FDA to authorize a booster shot of its vaccine.
