Novavax vs Pfizer Vaccines for COVID-19

(SHIELD Trial)

Age: 18+

Sex: Any

Trial Phase: Phase 4

Sponsor: Novavax

Disqualifiers: Other trials, Severe allergy, Recent vaccine

No Placebo Group All trial participants will receive the active study treatment (no placebo)

Prior Safety Data This treatment has passed at least one previous human trial

Compensation: Varies

Number of Visits: 1

What You Need to Know Before You Apply

What is the purpose of this trial?

This trial compares two updated COVID-19 vaccines, one from Novavax and the other from Pfizer, to assess their effects on health care workers and first responders. The focus is on reactogenicity, which involves checking for any side effects or reactions after vaccination. Participants will receive either the Novavax COVID-19 vaccine or the Pfizer mRNA COVID-19 vaccine to determine which is more effective. Suitable candidates for this trial include health care workers or first responders who have received at least one COVID-19 vaccine in the past four years and regularly work face-to-face with patients. As a Phase 4 trial, the vaccines are already FDA-approved and proven effective, and this research aims to understand how they benefit more patients.

Will I have to stop taking my current medications?

The trial information does not specify whether you need to stop taking your current medications. However, it does mention that you should not have received a COVID-19 vaccine within 60 days of enrollment and should not plan to receive other vaccines within 7 days after the study vaccination.

What is the safety track record for these treatments?

Research has shown that the Novavax COVID-19 vaccine is generally well-tolerated. The most common side effects include dizziness, tiredness, and headache. One study found that healthcare workers who received the Novavax vaccine reported fewer side effects than those who received the Pfizer vaccine.

For the Pfizer mRNA COVID-19 vaccine, research indicates it is safe for most people. Common side effects are mild, such as a sore arm at the injection site. However, some reports have noted heart inflammation, particularly in young males. Despite this, the vaccine remains effective and safe for most individuals.

Both vaccines have been widely used, providing extensive information on their safety. Participants should feel reassured by the comprehensive monitoring and research. ^{1 2 3 4 5}

Why are researchers enthusiastic about this study treatment?

Researchers are excited about these COVID-19 vaccines because they offer new formulations aimed at enhancing immune response against emerging virus variants. Unlike the earlier versions, the updated Novavax vaccine includes the JN.1 formula, potentially offering broader protection. Meanwhile, the Pfizer mRNA vaccine features the KP.2 formula, which might improve efficacy against current strains. These updates could mean better, more adaptive protection as COVID-19 continues to evolve.

What evidence suggests that this trial's treatments could be effective for COVID-19?

This trial will compare the Novavax COVID-19 vaccine with the Pfizer mRNA COVID-19 vaccine. Studies have shown that the Novavax vaccine effectively prevents COVID-19 symptoms, with a 90.4% efficacy and a strong immune response. The Pfizer mRNA vaccine is about 95% effective in preventing COVID-19 infection and has consistently lowered the chances of infection, hospitalization, and death. Both vaccines have proven safe and effective throughout the pandemic. Participants in this trial will receive either the updated Novavax vaccine or the Pfizer mRNA vaccine. ^{4 6 7 8 9}

Who Is on the Research Team?

Sarang K Yoon, MOH

Principal Investigator

University of Utah

Are You a Good Fit for This Trial?

This trial is for health care workers and first responders in the U.S. who are set to receive the updated 2024-25 COVID-19 vaccines. Specific eligibility criteria details were not provided, so it's unclear who exactly can or cannot participate.

Inclusion Criteria

I understand the study and can give my consent.

Health care workers or first responders who have direct face-to-face contact with patients

I plan to get the 2024-25 COVID-19 vaccine.

Exclusion Criteria

I plan to get other vaccines within a week after getting the study vaccine.

I have received a COVID-19 vaccine in the last 60 days.

Ongoing participation in other vaccine or investigational product trials within 90 days of study enrollment

Timeline for a Trial Participant

Screening

Participants are screened for eligibility to participate in the trial

2-4 weeks

Vaccination

Participants receive a single dose of either the 2024-25 Novavax or Pfizer-BioNTech mRNA COVID-19 vaccine

1 day

1 visit (in-person)

Post-vaccination Monitoring

Participants complete a post-vaccination questionnaire 48 hours after vaccine administration to report reactogenicity symptoms and impact on daily activities

2 days

Follow-up

Participants are monitored for safety and effectiveness after vaccination

4 weeks

What Are the Treatments Tested in This Trial?

Interventions

• Novavax COVID-19 vaccine
• Pfizer mRNA COVID-19 vaccine

Trial Overview The study compares reactogenicity (how the body reacts immediately after vaccination) between those getting an updated Novavax protein subunit vaccine and those receiving an updated Pfizer mRNA vaccine for COVID-19.

How Is the Trial Designed?

Group I: 2024-25 updated Novavax COVID-19 Active Control 1 Intervention

Participants will receive a single dose (0.5 ml) of study vaccine Novavax COVID-19 vaccine, 2024-2025 formula (JN.1 containing) in the deltoid muscle of the arm.

Group II: Pfizer mRNA COVID-19 Active Control 1 Intervention

Participants will receive a single dose (0.3 ml) of study vaccine Pfizer mRNA COVID-19 vaccine, 2024-2025 formula (KP.2 containing) in the deltoid muscle of the arm.

Who Is Running the Clinical Trial?

Novavax

Lead Sponsor

Trials

51

Recruited

111,000+

University of Utah

Collaborator

Trials

1,169

Recruited

1,623,000+

Published Research Related to This Trial

The NVX-CoV2373 COVID-19 vaccine demonstrated high efficacy rates of 89.7-90.4% in clinical trials, indicating it is effective in preventing COVID-19 in adults aged 18 and older.

The vaccine has an acceptable safety profile, with most adverse reactions being mild to moderate, and serious adverse events occurring at similar low rates in both NVX-CoV2373 and placebo groups, suggesting it is safe for use.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Safety of the NVX-CoV2373 COVID-19 vaccine in randomized placebo-controlled clinical trials. Smith, K., Hegazy, K., Cai, MR., et al.[2023]

In a study of over 1.8 million U.S. Veterans, mRNA-1273 (Moderna) showed a significantly lower risk of SARS-CoV-2 infection and related hospitalizations compared to BNT162b2 (Pfizer-BioNTech), with adjusted hazard ratios indicating a 26% and 37% reduced risk, respectively.

The differences in effectiveness were more pronounced during the Delta variant surge, suggesting that mRNA-1273 may offer better protection over time and against more transmissible variants.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Comparison of Moderna versus Pfizer-BioNTech COVID-19 vaccine outcomes: A target trial emulation study in the U.S. Veterans Affairs healthcare system. Ioannou, GN., Locke, ER., Green, PK., et al.[2022]

In a study of 19 internal medicine residents, the Pfizer-BioNTech COVID-19 vaccine was associated with a decrease in heart rate variability (HRV) after both doses, indicating a physiological response to vaccination.

Participants experienced an initial decrease in sleep duration following vaccination, which then increased over the following days, suggesting that sleep patterns may influence the body's response to the vaccine.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Physiologic Response to the Pfizer-BioNTech COVID-19 Vaccine Measured Using Wearable Devices: Prospective Observational Study. Hajduczok, AG., DiJoseph, KM., Bent, B., et al.[2021]

A total of 604,157 adverse events (AEs) were reported for COVID-19 vaccines, with the Pfizer-BioNTech and Moderna vaccines accounting for the majority of reports, indicating a need for ongoing safety monitoring.

While most reported AEs were mild, serious outcomes like hospitalization and life-threatening events were noted, particularly among older adults with pre-existing conditions, highlighting the importance of careful surveillance of vaccine safety.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Characteristics and Comparison of Adverse Events of Coronavirus Disease 2019 Vaccines Reported to the United States Vaccine Adverse Event Reporting System Between 14 December 2020 and 8 October 2021. Zou, C., Xue, X., Qian, J.[2022]

Citations

1. ir.novavax.com ir.novavax.com/press-releases/2025-08-27-Novavaxs-Nuvaxovid-TM-2025-2026-Formula-COVID-19-Vaccine-Approved-in-the-U-S

Novavax's Nuvaxovid™ 2025-2026 Formula COVID-19 ... Both clinical and preclinical data from Nuvaxovid confirm that the JN. 1 strain vaccination induces immunity across currently circulating JN.

2. cdc.gov cdc.gov/mmwr/volumes/74/wr/mm7406a1.htm

Interim Estimates of 2024–2025 COVID-19 Vaccine ... Vaccine effectiveness (VE) of 2024–2025 COVID-19 vaccine was 33% against COVID-19–associated emergency department (ED) or urgent care (UC) visits among adults ...

3. sciencedirect.com sciencedirect.com/science/article/pii/S0264410X2500074X

Efficacy, immunogenicity, and safety of the Novavax COVID ... Overall, the Novavax COVID-19 vaccine was immunogenic and had a tolerable safety profile across diverse populations of IIC; some outcomes varied ...

4. yalemedicine.org yalemedicine.org/news/novavax-covid-vaccine

Novavax's COVID-19 Vaccine: Your Questions Answered Trial results, published in The New England Journal of Medicine, showed it to have 90.4% overall efficacy.

5. ema.europa.eu ema.europa.eu/en/medicines/human/EPAR/nuvaxovid

Nuvaxovid | European Medicines Agency (EMA) The study found a 90.4% reduction in the number of symptomatic COVID-19 cases from 7 days after the second dose in adults who received Nuvaxovid (14 cases out ...

6. fda.gov fda.gov/files/vaccines%2C%20blood%20%26%20biologics/published/Package-Insert-and-Patient-Package-Insert-NUVAXOVID.pdf

Package Insert and Patient Package Insert - NUVAXOVID COVID-19 Vaccine, Adjuvanted (2023-2024 Formula). 76. Safety data accrued in Studies 1, 5, 6, and 7 are relevant to NUVAXOVID because the vaccines. 77.

7. cdc.gov cdc.gov/mmwr/volumes/72/wr/mm7231a4.htm

Safety Monitoring of Novavax COVID-19 Vaccine Among ... * The most commonly reported AEs included dizziness (33; 14.3%), fatigue (26; 11.3%), and headache (25; 10.9%). Among the 230 reports received, ...

8. pmc.ncbi.nlm.nih.gov pmc.ncbi.nlm.nih.gov/articles/PMC9397598/

Safety and Adverse Events Related to Inactivated COVID-19 ... The most common local side effects are pain, redness, and swelling at the injection site; while fatigue, body pain, headache, muscle pain, fever, and malaise ...

9. ir.novavax.com ir.novavax.com/press-releases/2025-04-15-SHIELD-Utah-Study-Shows-Novavaxs-COVID-19-Vaccine-Induces-Lower-Reactogenicity-Symptoms-Compared-to-mRNA

SHIELD-Utah Study Shows Novavax's COVID-19 Vaccine ... The SHIELD study found health care workers who received the Novavax vaccine reported significantly fewer reactogenicity events than Pfizer-BioNTech recipients.