Novavax COVID-19 Vaccine Safety, 2022–2023: 230 Reports, No New Concerns

The Novavax COVID-19 vaccine (NVX-CoV2373) is a recombinant spike protein nanoparticle vaccine with the Matrix-M adjuvant. It was authorized and recommended as a two-dose primary series for people 12 and older, and as a booster for adults 18 and older who can't or won't take an mRNA bivalent vaccine.

The reports

From July 13, 2022, to March 13, 2023, 69,227 Novavax doses were given to people 12 and older in the United States, and the Vaccine Adverse Event Reporting System (VAERS) received 230 reports of adverse events after vaccination.

The serious reports

Serious reports included one thrombosis, two pericarditis, one Guillain-Barré syndrome and two seizures; CDC reviewed the available records.

• Thrombosis: a woman with a clot in the axillary-subclavian vein 6 days after vaccination; her history suggested other possible causes, such as oral contraceptives.
• Pericarditis: one report, a man aged 40–49 with an abnormal electrocardiogram and fluid around the heart 3 days after vaccination, had possible other causes, including several earlier SARS-CoV-2 infections; the other didn't meet CDC's case definition.
• Guillain-Barré: no records were available.
• Seizure: records for one described new seizures in an adolescent, meeting the Brighton Collaboration definition.

The rest described chest pain, arrhythmia, illness, hospitalization, balance problems, worsened peripheral neuropathy, "vaccine failure" and unspecified events — mostly manufacturer reports without records to review.

Vaccination errors

66 (28.7%) reports were about vaccination errors, all non-serious; three mentioned an adverse event such as fever or fatigue. The most common error (21; 31.8%): giving a Novavax booster before it was authorized, in place of an mRNA vaccine.

What it means

Few Novavax doses were given — 0.01% of all COVID-19 vaccine doses — which limits the data. But what's available is consistent with the pre-authorization clinical trials, and no new safety concerns were found.

• Errors are preventable with training and a pre-vaccination checklist. The same product is generally recommended for all primary doses, with exceptions such as people who can't receive an mRNA vaccine.
• VAERS limits: reports can be biased, incomplete or uneven; VAERS generally can't show a vaccine caused an event; and about half the reports of special-interest events lacked medical records.

Sources

Based on Romanson B, Moro PL, Su JR, Marquez P, Nair N, Day B, DeSantis A, Shimabukuro TT, "Notes from the Field: Safety Monitoring of Novavax COVID-19 Vaccine Among Persons Aged ≥12 Years — United States, July 13, 2022–March 13, 2023," MMWR volume 72, number 31, Centers for Disease Control and Prevention; a work of the United States government in the public domain.