Characteristics of COVID-19 Vaccines in Relation to Pregnancy and Lactation

The information provided below is for readers based in the United States of America. Readers outside of the United States of America should seek the information from local sources.

Nuvaxovid or NVX-CoV-2601 (formerly NVX-CoV2373), is more commonly known as the Novavax vaccine and has been approved for emergency use in protecting against COVID-19 by the World Health Organization (WHO).

As of February 21, 2024, the vaccine has been authorized or approved in a growing number of countries including Australia, Canada, Austria, Belgium, Bulgaria, Croatia, Cyprus, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Israel, Italy, Japan, Latvia, Liechtenstein, Lithuania, Luxembourg, Malta, Netherlands, New Zealand, Norway, Poland, Portugal, Romania, Singapore, Slovakia, Slovenia, South Korea, Spain, Sweden, Switzerland, Taiwan, United Kingdom, United Arab Emirates and United States.

Currently, the Novavax COVID-19 vaccine is approved for use in people of age 12 years and older; clinical trials are advancing in children ages 6 months through 11 years. Novavax is an American biotechnology company that is based in Gaithersburg, Maryland. Currently, Novavax is collaborating with the Serum Institute of India on the production and manufacturing of the NVX-CoV2601 vaccine.

How The Novavax Vaccine Works

NVX-CoV2601 is what scientists call a protein subunit vaccine and is made of tiny units known as protein nanoparticles.

The protein molecules of these nanoparticles are genetically engineered and attached to a sub-stance called an adjuvant (adjuvants are molecules that, when combined with protein molecules, help produce a stronger immune response in people receiving the vaccine).

The specific adjuvant used in the Novavax vaccine is called a Matrix-M™ adjuvant.

In the case of the COVID-19 virus, the specific protein interest is the spike (S) glycoprotein (the protein that gives SARS-CoV2 - the virus that causes COVID-19 - the crown-like, or corona appearance when examined under an electron microscope).

There is no virus in the Novavax vaccine. The business end of the vaccine is merely the S glycoprotein attached to the Matrix-M™ adjuvant.

While the SARS-CoV2 virus uses the S glycoprotein to infect body cells, the S glycoprotein of the Novavax vaccine is locked into a particular shape that prevents it from acting like the S glycoprotein of actual virus particles; this means that the vaccine cannot harm body cells.

What the Novavax vaccine can do, and is designed to do, is to stimulate the immune system to respond the same way that it would upon detecting initial infection by the SARS-CoV2 virus. This response stimulates immune system production of special immune cells and special antibodies that attach to S glycoprotein.

Interestingly, genetically engineering and attaching a protein to an adjuvant isn’t a new concept. Scientists have used this process to successfully create other vaccines, including the HEPLISAV-B vaccine (to protect against hepatitis B and the Shingrix zoster vaccine (to prevent shingles).

How The Novavax Vaccine Is Administered

The Novavax vaccine is administered intramuscularly and injected into the deltoid muscle of your shoulder.

Effectiveness and Safety of The Novavax Vaccine

Large scale studies in the United Kingdom, the United States, and Mexico have demonstrated that the Novavax vaccine effectively prevents the development of COVID symptoms in over 90 percent of COVID-19 cases that would normally occur in unvaccinated people exposed to certain SARS-CoV2 variants (including the variants that dominated the pandemic prior to the surge of the Omicron variant).

When evaluating effectiveness in preventing the severe kind of COVID-19 that leads to admission to an intensive care unit (ICU), the effectiveness of the Novavax vaccine was close to 100 percent.

Considering this, scientists expect that the Novavax vaccine, like the other approved COVID-19 vaccines, will be extremely effective in preventing severe disease and death.

Pregnancy and Lactation Issues

The World Health Organization recommends vaccination in pregnant women “when the benefits of vaccination to the pregnant woman outweigh the potential risks”. Currently, the benefits of COVID-19 vaccination far outweigh potential risks, both in pregnancy and lactation.

The only exceptions to this recommendation are in rare cases of people who previously have suffered allergic reactions to ingredients in the vaccine, such as polyethylene glycol.

Specific to NVX-CoV2373, studies that have included pregnant women have demonstrated acceptable safety profiles for nanoparticle/Matrix-M™ used in the creation of the Novavax vaccine.

Adverse Effects Associated With The Novavax Vaccine

Undesirable or adverse effects of the Novavax vaccine commonly occur at the injection site and include pain, redness, and swelling. Like other COVID-19 vaccines, common effects felt throughout the body include tiredness, headache, chills, fever, nausea, and muscle aches.


Formica N, Mallory R, Albert G, Robinson M, Plested JS, Cho I, Robertson A, Dubovsky F, Glenn GM; 2019nCoV-101 Study Group. Different dose regimens of a SARS-CoV-2 recombinant spike protein vaccine (NVX-CoV2373) in younger and older adults: A phase 2 randomized placebo-controlled trial. PLoS Med. 2021 Oct 1;18(10):e1003769. doi: 10.1371/journal.pmed.1003769. PMID: 34597298; PMCID: PMC8486115.

Heath PT, Galiza EP, Baxter DN, et al.; 2019nCoV-302 Study Group. Safety and Efficacy of NVX-CoV2373 Covid-19 Vaccine. N Engl J Med. 2021 Sep 23;385(13):1172-1183. doi: 10.1056/NEJMoa2107659. Epub 2021 Jun 30. PMID: 34192426; PMCID: PMC8262625.

Novavax. Novavax COVID-19 Vaccine Demonstrates 90% Overall Efficacy and 100% Protection Against Moderate and Severe Disease in PREVENT-19 Phase 3 Trial. Accessed January 19, 2022

Novavax. All Updates On Our COVID-19 Vaccine Effort. Accessed January 19, 2022

World Health Organization. COVID-19 vaccines side effects and safety. Accessed January 19, 2022