Full Press Release Details
ESCMID: Sanofi's Nuvaxovid COVID-19 vaccine
showed better tolerability than mNEXSPIKE in head-to-head study
Paris, April 18, 2026. Sanofi's protein-based non-mRNA COVID-19 vaccine Nuvaxovid (NVX-CoV2705) demonstrated statistically significant lower systemic reactogenicity (the expected
side effects that might occur following vaccination) compared to mNEXSPIKE (mRNA-1283), Moderna's latest mRNA COVID-19 vaccine, across all pre-specified endpoints
in the COMPARE study. The randomized, double-blind study, which enrolled 1,000 adults in the US, was presented at the European Society of Clinical Microbiology and Infectious Diseases (ESCMID) Global Congress in Munich, Germany.
These results address a persistent challenge: despite the end of the pandemic, COVID-19 continues to cause
significant hospitalizations and deaths globally, while placing considerable strain on health systems during seasonal peaks. Yet vaccination uptake remains low, with concerns about vaccine side effects ranking among the top reasons cited by adults
for not getting vaccinated against COVID-19.
In the COMPARE study, when side effects did occur with
Nuvaxovid, they were less severe and shorter in duration compared to mNEXSPIKE. Severe systemic symptoms (body-wide reactions such as fatigue, headache, or fever) that prevent people from carrying out their normal daily activities were more than 50%
less frequent with Nuvaxovid, affecting fewer than one in ten Nuvaxovid recipients compared to one in five mNEXSPIKE recipients, an analysis of the data showed. Severe local symptoms (reactions at the injection site such as pain,
redness, or swelling) with Nuvaxovid were rare, and more than 75% less frequent compared to mNEXSPIKE. This was reflected in the study participants' own experience: those who received Nuvaxovid were nearly twice as likely as mNEXSPIKE
recipients to say they would definitely choose the same vaccine type again the following year.
The study met its primary endpoint - the
probability of experiencing at least one systemic reaction within seven days of vaccination - with statistical significance, with 91.6% of mNEXSPIKE recipients affected compared to 83.6% of Nuvaxovid recipients (risk
difference: 8.0%; 95% CI: 4.0%-12%; p<0.001).
The study also showed that 61.3% of mNEXSPIKE recipients experienced moderate-to-severe (Grade 2 or 3) systemic symptoms versus 43.1% of Nuvaxovid recipients (risk difference: 18%; 95% CI: 12%-24%; p<0.001),
and 58.7% of mNEXSPIKE recipients experienced moderate-to-severe local symptoms versus 38.7% of Nuvaxovid recipients (risk difference: 20%; 95%
CI: 14%-26%; p<0.001).
"This study was designed to answer a question that matters deeply to clinicians and
patients alike: how do different COVID-19 vaccines compare in terms of reactogenicity and patient experience? The answer is
clear," said Dr. Marcel E. Curlin, Principal Investigator of the COMPARE study and Professor of Medicine at Oregon Health & Science
University. "Across every measure we evaluated, we observed that the recombinant protein-based vaccine consistently exhibited lower reactogenicity and less disruption to patient activities than the comparator mRNA vaccine.
Individuals cite side effects as a reason they avoid COVID-19 vaccination. These differences could have a significant impact on improving vaccination uptake."
"The patient experience with vaccination is essential, because it
determines not only whether people get vaccinated, but also whether they come back year after year for routine protection," said Thomas Triomphe, Executive Vice President, Vaccines, Sanofi. "These
results show that Nuvaxovid can play a meaningful role in making routine COVID-19 vaccination a reality for more people, which is how we can help address the continued
burden of this disease on patients and health systems."
Beyond clinical measures, the COMPARE study also captured patient-reported
outcomes reinforcing the real-world relevance of Nuvaxovid's tolerability profile. Nuvaxovid recipients reported less disruption to daily activities, including work, school, recreational activities, and caretaking responsibilities, over the
seven days following vaccination. Notably, more than half of all participants reported scheduling their vaccination on a specific day of the week in anticipation of potential side effects, highlighting the extent to which tolerability concerns shape
vaccination behavior. Together, these findings suggest that a better tolerability experience may favor greater vaccine confidence and willingness to return for routine immunization.
Coronavirus disease (COVID-19) is an infectious disease caused by the SARS-CoV-2 virus. Most people infected with the virus will experience mild to moderate respiratory illness and recover without requiring special treatment. However, some will become seriously ill resulting in
hospitalization and death.
The disease not only causes immediate health impacts but also increases the long-term risk of cardiovascular
complications, including heart attacks and strokes, and older adults hospitalized for COVID-19 face substantially higher mortality risk than those hospitalized for influenza. Older adults and those with
chronic conditions - including cardiovascular disease, chronic lung disease, diabetes, and obesity - face the highest risk of severe illness. In the US, an estimated 74% of adults have at least one such risk factor, underscoring the scale of the
vulnerable population that stands to benefit from effective and well-tolerated COVID-19 vaccination.
Nuvaxovid (NVX-CoV2705) is a protein-based, adjuvanted vaccine for active immunization to prevent COVID-19 caused by
SARS-CoV-2. It is developed using the recombinant technology, an established platform with a long track record across multiple vaccine types. Nuvaxovid has been shown to
have a tolerable side-effect profile suitable for routine vaccination and has also demonstrated high efficacy against COVID-19 as a primary vaccination in two pivotal phase 3 studies.
As the pandemic has now evolved into an endemic phase, having multiple vaccine options becomes increasingly important for sustainable public health
strategies. Nuvaxovid offers healthcare systems a protein-based vaccine option with an established safety and tolerability profile to add to their routine vaccination programs. This diversity is particularly valuable for addressing vaccine
Nuvaxovid was originally licensed by Novavax. Sanofi is now market authorization holder for Nuvaxovid in the US, the EU and the United
Kingdom. Building on its commercial launch in the US, Taiwan, and Morocco in 2025, Sanofi is expanding Nuvaxovid's availability to additional markets - including the United Kingdom, Germany, and Canada - from 2026 onwards.
R&D driven, AI-powered biopharma company committed to improving people's lives and delivering compelling growth. We apply our deep understanding of the immune system to invent medicines and vaccines
that treat and protect millions of people around the world, with an innovative pipeline that could benefit millions more. Our team is guided by one purpose: we chase the miracles of science to improve people's lives; this inspires us to
drive progress and deliver positive impact for our people and the communities we serve, by addressing the most urgent healthcare, environmental, and societal challenges of our time. Sanofi is listed on EURONEXT: SAN and NASDAQ: SNY
Sandrine Guendoul | +33 6 25 09 14 25 | sandrine.guendoul@sanofi.com
Evan Berland | +1 215 432 0234 |
Bourhis | +33 6 75 06 43 81 | leo.lebourhis@sanofi.com
Victor Rouault | +1 617 356 4751 | victor.rouault@sanofi.com
Timothy Gilbert | +1 516 521 2929 |
Ubaldi | +33 6 30 19 66 46 | lea.ubaldi@sanofi.com
Ekaterina Pesheva | +1 410 926 6780 | ekaterina.pescheva@sanofi.com
Thomas Kudsk Larsen |+ 44 7545 513 693 | thomas.larsen@sanofi.com
Aliz Kaisserian | + 33 6 47 04 12 11 |
Browne | + 1 781 249 1766 | keita.browne@sanofi.com
Nathalie Pham | + 33 7 85 93 30 17 | nathalie.pham@sanofi.com
Nina Goworek | +1 908 569 7086 |
Ch telet | + 33 6 80 80 89 90 | thibaud.chatelet@sanofi.com
Yun Li | +33 6 84 00 90 72 | yun.li3@sanofi.com
Sanofi forward-looking statement
This press release contains forward-looking statements within the meaning of applicable securities laws, including the Private Securities Litigation
Reform Act of 1995, as amended. Forward-looking statements are statements that are not historical facts. These statements include projections and estimates and their underlying assumptions regarding the marketing and other potential of the product;
regarding potential future events and revenues from the product. Words such as "expect," "anticipate," "believe," "intend," "estimate," "plan," "can,"
"contemplate," "could," "is designed to," "may," "might," "potential," "objective," "attempt," "target," "project,"
"strategy," "strive," "desire," "predict," "forecast," "ambition," "guideline," "seek," "should," "will," "goal," or
the negative of these and similar expressions are intended to identify forward-looking statements. Although Sanofi's management believes that the expectations reflected in such forward-looking statements are reasonable, investors are cautioned
that forward-looking information and statements are subject to various risks and uncertainties, many of which are difficult to predict and generally beyond the control of Sanofi, that could cause actual results and developments to differ materially
from those expressed in, or implied or projected by, the forward-looking information and statements. These risks, uncertainties and assumptions include among other things, unexpected regulatory actions or delays, or government regulation generally,
that could affect the availability or commercial potential of the product, the fact that product may not be commercially successful; authorities' decisions regarding whether and when to approve a product candidate; political pressure in the
United States to mandate lower drug prices including "most favored nation" pricing for State Medicaid programs; the uncertainties inherent in research and development, including future clinical data and analysis of existing clinical data
relating to the product, including post marketing, unexpected safety, quality or manufacturing issues; competition in general; risks associated with intellectual property and any related pending or future litigation and the ultimate outcome of such
litigation, and volatile economic and market conditions, and the impact that global crises may have on us, our customers, suppliers, vendors, and other business partners, and the financial condition of any one of them, as well as on our employees
and on the global economy as a whole. The risks and uncertainties also include the uncertainties discussed or identified in the public filings with the SEC and the French Markets Authority (AMF) made by Sanofi, including those listed under
"Risk Factors" and "Cautionary Statement Regarding Forward-Looking Statements" in Sanofi's annual report on Form 20-F for the year ended December 31, 2025 or contained in our
periodic reports on Form 6-K. Other than as required by applicable law, Sanofi does not undertake any obligation to update or revise any forward-looking information or statements. In light of these risks,
uncertainties and assumptions, you should not place undue reliance on any forward-looking statements contained herein.