Polyrizon Ltd 20-F for FY2024

Polyrizon Ltd. (PLRZ)

20-F 2025-03-11 For: 2024-12-31

Added on April 11, 2026

About this 20-F

Polyrizon Ltd filed this 20-F on March 11, 2025, covering the fiscal year ended December 31, 2024 (FY2024).

Headline figures

Fiscal year ended December 31, 2024, as reported in this filing, compared with the same period a year earlier where the filing states it.

Net loss: $1.55M; compared with a net loss of $600K a year earlier
Diluted EPS: $0.50; up 66.7% from $0.30 a year earlier

Search and read filings like this one from Claude or ChatGPT with the SEC filings MCP server →

State of Israel		5 Ha-Tidhar Street Raanana, 4366507, Israel
(Jurisdiction of incorporation or organization)		(Address of principal executive offices)

Title of each class to be registered		Trading Symbol(s)		Name of each exchange on which each class is to be registered
Ordinary Shares, no par value per share		PLRZ		The Nasdaq Stock Market LLC

Large accelerated filer ☐	Accelerated filer ☐	Non-accelerated filer ☒
		Emerging Growth Company ☒

		Page
INTRODUCTION		iii
EMERGING GROWTH COMPANY STATUS		iii
TRADEMARKS		iii
CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS		iv
MARKET, INDUSTRY, AND OTHER DATA		v

PART I		1

ITEM 1.	IDENTITY OF DIRECTORS, SENIOR MANAGEMENT AND ADVISERS	1
ITEM 2.	OFFER STATISTICS AND EXPECTED TIMETABLE	1
ITEM 3.	KEY INFORMATION	1
A.	[Reserved]	1
B.	Capitalization and Indebtedness	1
C.	Reasons for the Offer and Use of Proceeds	1
D.	Risk Factors	1
ITEM 4.	INFORMATION ON THE COMPANY	52
A.	History and Development of the Company	52
B.	Business Overview	53
C.	Organizational Structure	86
D.	Property, Plants and Equipment	86
ITEM 4A.	UNRESOLVED STAFF COMMENTS	86
ITEM 5.	OPERATING AND FINANCIAL REVIEW AND PROSPECTS	87
A.	Operating Results	87
B.	Liquidity and Capital Resources	89
C.	Research and Development, Patents and Licenses	92
D.	Trend Information	92
E.	Critical Accounting Estimates	92
ITEM 6.	DIRECTORS, SENIOR MANAGEMENT AND EMPLOYEES	93
A.	Directors and Senior Management	93
B.	Compensation	97
C.	Board Practices	98
D.	Employees	110
E.	Share Ownership	110
F.	Disclosure of a registrant’s action to recover erroneously awarded compensation	111
ITEM 7.	MAJOR SHAREHOLDERS AND RELATED PARTY TRANSACTIONS	111
A.	Major Shareholders	111
B.	Related Party Transactions	113
C.	Interests of Experts and Counsel	114
ITEM 8.	FINANCIAL INFORMATION	114
A.	Consolidated Statements and Other Financial Information	114
B.	Significant Changes	115
ITEM 9.	THE OFFER AND LISTING	115
A.	Offer and Listing Details	115
B.	Plan of Distribution	115
C.	Markets	115
D.	Selling Shareholders	115
E.	Dilution	115
F.	Expenses of the Issue	115

ITEM 10.	ADDITIONAL INFORMATION	115
A.	Share Capital	115
B.	Articles of Association	115
C.	Material Contracts	115
D.	Exchange Controls	116
E.	Taxation	116
F.	Dividends and Paying Agents	124
G.	Statement by Experts	124
H.	Documents on Display	124
I.	Subsidiary Information	124
J.	Annual Report to Security Holders	124
ITEM 11.	QUANTITATIVE AND QUALITATIVE DISCLOSURES ABOUT MARKET RISK	124
ITEM 12.	DESCRIPTION OF SECURITIES OTHER THAN EQUITY SECURITIES	125

PART II		126

ITEM 13.	DEFAULTS, DIVIDEND ARREARAGES AND DELINQUENCIES	126
ITEM 14.	MATERIAL MODIFICATIONS TO THE RIGHTS OF SECURITY HOLDERS AND USE OF PROCEEDS	126
ITEM 15.	CONTROLS AND PROCEDURES	126
ITEM 16.	[RESERVED]	126
ITEM 16A.	AUDIT COMMITTEE FINANCIAL EXPERT	126
ITEM 16C.	PRINCIPAL ACCOUNTANT FEES AND SERVICES	127
ITEM 16D.	EXEMPTIONS FROM THE LISTING STANDARDS FOR AUDIT COMMITTEES	127
ITEM 16E.	PURCHASES OF EQUITY SECURITIES BY THE ISSUER AND AFFILIATED PURCHASERS	127
ITEM 16F.	REGISTRANT’S CERTIFYING ACCOUNTANT	127
ITEM 16G.	CORPORATE GOVERNANCE	128
ITEM 16I	DISCLOSURE REGARDING FOREIGN JURISDICTIONS THAT PREVENT INSPECTIONS	129
ITEM 16J	INSIDER TRADING POLICIES	130
ITEM 16K	CYBERSECURITY	130

PART III		131

ITEM 17.	FINANCIAL STATEMENTS	131
ITEM 18.	FINANCIAL STATEMENTS	131
ITEM 19.	EXHIBITS	131
SIGNATURES		133

	●	We have incurred significant losses since our inception. We anticipate that we will continue to incur significant losses for the foreseeable future. We have never generated any revenue from product candidates sales and may never be profitable.

	●	We expect that we will need to raise substantial additional funding, which may not be available on acceptable terms, or at all. Failure to obtain funding on acceptable terms and on a timely basis may require us to curtail, delay or discontinue our product candidates’ development efforts or other operations.

	●	We depend on enrollment of patients in our upcoming clinical trials in order to continue development of our product candidates.

	●	We may not receive, or may be delayed in receiving, the necessary clearances or approvals for our product candidates, failure to timely obtain necessary clearances or approvals would adversely affect our ability to grow our business.

	●	Legislative or regulatory reforms in the United States or the European Union may make it more difficult and costly for us to obtain regulatory clearances or approvals for our product candidates or to manufacture, market or distribute our product candidates after clearance or approval is obtained.

	●	We are heavily dependent on the success of our C&C product candidates.

	●	Our C&C and T&T technologies are novel technologies, which makes it difficult to accurately and reliably predict the time and cost of development and regulatory approval.

	●	As an organization, we have not previously conducted pivotal clinical trials, and we may be unable to do so for any product candidates we may develop, including our T&T platform product candidates.

	●	Our product candidates and the administration of our product candidates may cause undesirable side effects or have other properties that could delay or prevent their regulatory approval.

	●	We may be subject, directly or indirectly, to U.S. federal and state healthcare fraud and abuse laws, false claims laws, physician payment transparency laws and health information privacy and security laws. If we are unable to comply, or have not fully complied, with such laws, we could face substantial penalties.

	●	We face intense competition in an environment of rapid technological change, which may adversely affect our financial condition and our ability to successfully market or commercialize our product candidates.

	●	The misuse or off-label use of our product candidates may harm our reputation in the marketplace, result in injuries that lead to product candidates liability suits or result in costly investigations, fines or sanctions by regulatory bodies if we are deemed to have engaged in the promotion of these uses, any of which could be costly to our business.

	●	Begin our planned clinical trial of our C&C product candidates in the fourth quarter of 2025;

	●	seek regulatory and marketing approvals for any product candidates that successfully complete clinical trials;

	●	advance our preclinical and research and development programs;

	●	identify, assess, acquire, license and/or develop other product candidates;

	●	manufacture current good manufacturing practices, or cGMP, material for clinical trials or potential commercial sales;

	●	establish a sales, marketing and distribution infrastructure to commercialize any product candidates for which we may obtain marketing approval;

	●	hire personnel and invest in additional infrastructure to support our operations as a public company and expand our product candidates’ development;

	●	enter into agreements to license intellectual property from third parties;

	●	develop, maintain, protect and expand our intellectual property portfolio; and

	●	experience any delays or encounter issues with respect to any of the above, including, but not limited to, failed trials, complex results, safety issues or other regulatory challenges that require longer follow-up of existing clinical trials, additional major clinical trials or additional supportive studies in order to pursue marketing approval.

	●	our inability to demonstrate to the satisfaction of the FDA or the applicable regulatory entity or notified body that our product candidates are safe or effective for their intended uses;

	●	the disagreement of the FDA or the applicable foreign regulatory body with the design or the interpretation of data from pre- clinical studies or clinical trials;

	●	serious and unexpected adverse effects experienced by participants in our clinical trials;

	●	the data from our pre-clinical studies and clinical trials may be insufficient to support clearance or approval, where required;

	●	our inability to demonstrate that the clinical and other benefits of the device outweigh the risks;

	●	the manufacturing process or facilities we use may not meet applicable requirements; and

	●	the potential for approval policies or regulations of the FDA or applicable foreign regulatory bodies to change significantly in a manner rendering our clinical data or regulatory filings insufficient for clearance or approval.

	●	improves the traceability of medical devices throughout the supply chain to the end-user or patient through a unique identification number;

	●	sets up a central database to provide patients, healthcare professionals and the public with comprehensive information on product available in the EU; and

	●	Provides strengthened rules for the assessment of certain high-risk devices, which may have to undergo an additional check by experts before they are placed on the market.

	●	our ability to initiate our clinical trials;

	●	Success in in-vitro cell culture assays or other non-clinical experiments or animal studies does not ensure that later, clinical trials will be successful nor does it predict final results.

	●	acceptance by the FDA, EMA or other regulatory agencies of our strategies for seeking regulatory approvals for our C&C product candidates and any future product candidates, including our proposed indications, primary and secondary endpoint assessments and measurements, safety evaluations and regulatory pathways;

	●	the acceptance by the FDA, EMA or other regulatory agencies of the number, design, size, conduct and implementation of our clinical trials, our trial protocols and the interpretation of data from preclinical studies or clinical trials;

	●	our ability to successfully initiate and complete clinical trials of our C&C product candidates and any future product candidates, including timely patient enrollment and acceptable safety and efficacy data and our ability to demonstrate the safety and efficacy of the product candidates undergoing such clinical trials;

	●	the willingness of the FDA, EMA or other regulatory agencies to schedule an advisory committee meeting in a timely manner in connection with our regulatory submissions, if such advisory committee meetings are required;

	●	the recommendation of the FDA’s advisory committee to approve our applications to market our C&C product candidates and any future product candidates in the United States, and the EMA’s approval to market our C&C product candidates in the European Union, if such advisory committee reviews are scheduled, without limiting the approved labeling, specifications, distribution or use of the product candidates, or imposing other restrictions;

	●	the satisfaction of the FDA, EMA or other regulatory agencies with the safety and efficacy of C&C product candidates and any future product candidates;

	●	the prevalence and severity of adverse events associated with C&C product candidates and any future product candidates;

	●	the timely and satisfactory performance by third-party contractors, trial sites and principal investigators of their obligations in relation to our clinical trials;

	●	our success in educating medical professionals and patients about the benefits, administration and use of our C&C product candidates and any future product candidates, if approved;

	●	the availability, perceived advantages, relative cost, safety and efficacy of alternative and competing product for the indications addressed by our C&C product candidates and any future product candidates;

	●	the effectiveness of our marketing, sales and distribution strategy, and operations, as well as that of any current and future licensees;

	●	our ability to scale, validate and maintain a commercially viable manufacturing process that is cGMP-compliant;

	●	our ability to obtain, protect and enforce our intellectual property rights with respect to our C&C product candidates, any future product candidates and our C&C technology; and

	●	changes to regulatory guidelines.

	●	regulatory requests for additional analyses, reports, data, non-clinical and preclinical studies and clinical trials;

	●	our inability to demonstrate that a product candidate is safe and effective for the target indication to the satisfaction of the FDA, EMA or other regulatory agencies;

	●	the FDA’s, EMA’s, or other regulatory agencies’ disagreement with our trial protocol, the interpretation of data from preclinical studies or clinical trials, or adequacy of the conduct and control of clinical trials;

	●	clinical holds, other regulatory objections to commencing or continuing a clinical trial or the inability to obtain regulatory approval to commence a clinical trial in countries that require such approvals;

	●	the population studied in the clinical trial may not be sufficiently broad or representative to assess safety in the patient population for which we seek approval;

	●	unfavorable or inconclusive results of clinical trials and supportive non-clinical studies, including unfavorable results regarding safety or efficacy of a product candidate observed in clinical trials;

	●	our inability to demonstrate that clinical or other benefits of a product candidate outweighs any safety or other perceived risks;

	●	any determination that a clinical trial presents unacceptable health risks to subjects;

	●	our inability to obtain approval from institutional review boards, or IRBs, to conduct clinical trials at their respective sites;

	●	the FDA’s determination that the regulatory pathways under FFDCA Section 505(b)(2), or Section 505(b)(2), or Section 510(k) are not available for a product candidate;

	●	the non-approval of the formulation, labeling or the specifications of a product candidate;

	●	the failure to accept the manufacturing processes or facilities at of third-party manufacturers with which we contract;

	●	the potential for approval policies or regulations of the FDA, EMA or other regulatory agencies to significantly change in a manner rendering our clinical data insufficient for approval; or

	●	resistance to approval from the advisory committees of the FDA, EMA or other regulatory agencies for any reason including safety or efficacy concerns.

	●	generate sufficient preclinical, toxicology, or other in vivo or in vitro data to support the initiation or continuation of clinical trials;

	●	obtain regulatory approval, or feedback on trial design, in order to commence a trial;

	●	identify, recruit and train suitable clinical investigators;

	●	reach agreement on acceptable terms with prospective CROs and clinical trial sites, the terms of which can be subject to extensive negotiation and may vary significantly among CROs and clinical trial sites, and have such CROs and sites effect the proper and timely conduct of our clinical trials;

	●	obtain and maintain IRB approval at each clinical trial site;

	●	identify, recruit and enroll suitable patients to participate in a trial;

	●	have a sufficient number of patients complete a trial or return for post-treatment follow-up;

	●	ensure clinical investigators and clinical trial sites observe trial protocol or continue to participate in a trial;

	●	address any patient safety concerns that arise during the course of a trial;

	●	address any conflicts with new or existing laws or regulations;

	●	add a sufficient number of clinical trial sites;

	●	manufacture sufficient quantities at the required quality of product candidate for use in clinical trials; or

	●	raise sufficient capital to fund a trial.

	●	we may receive feedback from regulatory authorities that requires us to modify the design of our clinical trials;

	●	clinical trials of a product candidate may produce negative or inconclusive results, and we may decide, or regulators may require us, to conduct additional clinical trials or abandon drug development programs;

	●	the number of patients required for clinical trials of a product candidate may be larger than we anticipate, enrollment in these clinical trials may be slower than we anticipate or participants may drop out of these clinical trials at a higher rate than we anticipate;

	●	our third-party contractors may fail to comply with regulatory requirements or meet their contractual obligations to us in a timely manner, or at all;

	●	regulators or IRBs may not authorize us or our investigators to commence a clinical trial or conduct a clinical trial at a prospective trial site or amend a trial protocol;

	●	we may have delays in reaching or fail to reach agreement on acceptable clinical trial contracts or clinical trial protocols with prospective trial sites and CROs;

	●	we or our investigators might have to suspend or terminate clinical trials of a product candidate for various reasons, including non- compliance with regulatory requirements, a finding that a product candidate have undesirable side effects or other unexpected characteristics, or a finding that the participants are being exposed to unacceptable health risks;

	●	the cost of clinical trials of a product candidate may be greater than we anticipate;

	●	the supply or quality of a product candidate or other materials necessary to conduct clinical trials of such product candidate may be insufficient or inadequate;

	●	there may be changes in government regulations or administrative actions;

	●	a product candidate may have undesirable adverse effects or other unexpected characteristics;

	●	we may not be able to demonstrate that a produce candidate’s clinical and other benefits outweigh its safety risks;

	●	we may not be able to demonstrate that a product candidate provides an advantage over current standards of care of future competitive therapies in development;

	●	regulators may revise the requirements for approving a product candidate, or such requirements may not be as we anticipate; and

	●	any future collaborators that conduct clinical trials may face any of the above issues, and may conduct clinical trials in ways they view as advantageous to them but that are suboptimal for us.

	●	regulatory authorities may suspend or withdraw approvals of such product candidates;

	●	regulatory authorities may require additional warnings on the label, such as a “black box” warning or contraindication;

	●	additional restrictions may be imposed on the marketing of the particular product candidates or the manufacturing processes for the product candidates or any component thereof;

	●	we may be required to create a REMS, which could include a medication guide outlining the risks of such side effects for distribution to patients, a communication plan for healthcare providers and/or other elements to assure safe use;

	●	we may be required to recall a product candidates, change the way a product candidate is administered or conduct additional clinical trials;

	●	we could be sued and held liable for harm caused to patients;

	●	the product candidates may become less competitive; and

	●	our reputation may suffer.

	●	suspend or withdraw regulatory approval;

	●	suspend any of our ongoing clinical trials;

	●	refuse to approve pending applications or supplements to approved applications submitted by us or our strategic partners;

	●	restrict the marketing or manufacturing of our product candidates;

	●	seize or detain product candidates, or require a product candidates recall;

	●	refuse to permit the import or export of our product candidates; or

	●	refuse to allow us to enter into government contracts.

	●	The U.S. federal false claims laws, including the False Claims Act, or FCA, and civil monetary penalties laws, which prohibit any person or entity from, among other things, knowingly presenting, or causing to be presented, a false, fictitious or fraudulent claim for payment to, or approval by, the U.S. federal government or knowingly making, using or causing to be made or used a false record or statement material to a false or fraudulent claim to the U.S. federal government. As a result of a modification made by the Fraud Enforcement and Recovery Act of 2009, a claim includes “any request or demand” for money or property presented to the U.S. government. In addition, manufacturers can be held liable under the FCA even when they do not submit claims directly to government third-party payors if they are deemed to “cause” the submission of false or fraudulent claims. The FCA also permits a private individual acting as a “whistleblower” to bring actions on behalf of the federal government alleging violations of the FCA and to share in any monetary recovery. FCA liability is potentially significant in the healthcare industry because the statute provides for treble damages and mandatory penalties per false claim or statement. Government enforcement agencies and private whistleblowers have investigated pharmaceutical companies for or asserted liability under the FCA for a variety of alleged promotional and marketing activities, such as providing free products to customers with the expectation that the customers would bill federal programs for the products; providing consulting fees and other benefits to physicians to induce them to prescribe products; engaging in promotion for “off-label” uses; and submitting inflated best price information to the Medicaid Rebate Program.

	●	The U.S. Health Insurance Portability and Accountability Act of 1996, or HIPAA, prohibits, among other actions, knowingly and willfully executing, or attempting to execute, a scheme to defraud any healthcare benefit program, including private third-party payors, knowingly and willfully embezzling or stealing from a healthcare benefit program, willfully obstructing a criminal investigation of a healthcare offense, and knowingly and willfully falsifying, concealing or covering up a material fact or making any materially false, fictitious or fraudulent statement in connection with the delivery of or payment for healthcare benefits, items or services.

	●	HIPAA, as amended by the Health Information Technology for Economic and Clinical Health Act, or HITECH, and their respective implementing regulations, impose, among other things, specified requirements relating to the privacy, security and transmission of individually identifiable health information held by covered entities, which include certain healthcare providers, health plans and healthcare clearinghouses, and their business associates, which include individuals or entities that perform services for covered entities that involve the creation, use, maintenance or disclosure of, individually identifiable health information as well as their covered subcontractors. HITECH also created new tiers of civil monetary penalties, amended HIPAA to make civil and criminal penalties directly applicable to business associates, and gave state attorneys general new authority to file civil actions for damages or injunctions in U.S. federal courts to enforce the federal HIPAA laws and seek attorneys’ fees and costs associated with pursuing federal civil actions. In addition, state laws govern the privacy and security of health information in specified circumstances, many of which differ from each other in significant ways and may not have the same effect, thus complicating compliance efforts.

	●	European and other foreign law equivalents of each of the laws, including reporting requirements detailing interactions with and payments to healthcare providers.

	●	reduced control for certain aspects of manufacturing activities;

	●	termination or nonrenewal of manufacturing and service agreements with third parties in a manner or at a time that is costly or damaging to us; and

	●	disruptions to the operations of our third-party manufacturers and service providers caused by conditions unrelated to our business or operations, including the bankruptcy of the manufacturer or service provider.

	●	additional potentially relevant third-party patent rights;

	●	complexities and difficulties in obtaining protection and enforcing our intellectual property;

	●	difficulties in staffing and managing foreign operations;

	●	complexities associated with managing multiple payor reimbursement regimes, government payors, prince controls or patient self-pay systems;

	●	limits in our ability to penetrate international markets;

	●	financial risks, such as longer payment cycles, difficulty collecting accounts receivable, the impact of local and regional financial crises on demand and payment for our product candidates and exposure to foreign currency exchange rate fluctuations;

	●	an outbreak of a contagious disease, which may cause us or our distributors, third party vendors and manufacturers and/or customers to temporarily suspend our or their respective operations in the affected city or country;

	●	natural disasters, political and economic instability, including wars, terrorism, and political unrest, boycotts, curtailment of trade, and other business restrictions;

	●	certain expenses including, among others, expenses for travel, translation and insurance; and

	●	regulatory and compliance risks that relate to maintaining accurate information and control over sales and activities that may fall within the purview of the U.S. Foreign Corrupt Practices Act its books and records provisions, or its anti-bribery provisions.

	●	the cost of treatment relative to alternative treatments;

	●	the prevalence and severity of any adverse side effects;

	●	product candidates labeling or product candidates insert requirements of the FDA or other regulatory authorities, including any limitations or warnings contained in a product candidate’s approved labeling;

	●	distribution and use restrictions imposed by the FDA or agreed to by us as part of a mandatory or voluntary risk management plan;

	●	our ability to obtain third-party coverage and adequate reimbursement;

	●	the willingness of patients to pay for drugs out of pocket in the absence of third-party coverage;

	●	the demonstration of the effectiveness of our product candidates in reducing the cost of treatment;

	●	the strength of marketing and distribution support;

	●	the timing of market introduction of competitive products;

	●	the availability of product candidates and their ability to meet market demand; and

	●	publicity concerning our product candidates or competing products and treatments.

	●	a covered benefit or part of a covered benefit under its health plan;

	●	safe, effective and medically necessary;

	●	appropriate for the specific patient;

	●	cost-effective; and

	●	neither experimental nor investigational.

	●	not being required to comply with the auditor attestation requirements in the assessment of our internal control over financial reporting;

	●	Section 107 of the JOBS Act, which provides that an “emerging growth company” can take advantage of the extended transition period provided in Section 7(a)(2)(B) of the Securities Act of 1933, as amended, or the Securities Act, for complying with new or revised accounting standards. This means that an “emerging growth company” can delay the adoption of certain accounting standards until those standards would otherwise apply to private companies. We have elected to delay such adoption of new or revised accounting standards. As a result of this adoption, our financial statements may not be comparable to companies that comply with the public company effective date;

	●	not being required to comply with any requirement that may be adopted by the Public Company Accounting Oversight Board regarding mandatory audit firm rotation or a supplement to the auditor’s report providing additional information about the audit and the financial statements;

	●	reduced disclosure obligations regarding executive compensation; and

	●	exemptions from the requirements of holding a nonbinding advisory vote on executive compensation and shareholder approval of any golden parachute payments not previously approved.


Figure 1 - The effect of the C&C technology (PL-14) in reduction the IL-8 secretion in response to dust mite allergen Der P1. A lower bar indicates lower inflammation (lowercase letters are significantly different from each other (P< 0.05)).	Figure 2 - The effect of the C&C technology (PL-14) in reduction the IL-8 secretion in response to timothy grass allergen Phl P1. A lower bar indicates lower inflammation (lowercase letters are significantly different from each other (P< 0.05))


Figure 3 - The effect of the C&C technology (PL-14) in reduction the IL-8 secretion in response to European hornbeam allergen Car B1. A lower bar indicates lower inflammation (lowercase letters are significantly different from each other (P< 0.05)	Figure 4 - The effect of the C&C technology (PL-14) in reduction the IL-8 secretion in response to European dust mite allergen Der F1. A lower bar indicates lower inflammation (lowercase letters are significantly different from each other (P< 0.05))


Figure 5 - The effect of the C&C technology (PL-15) in protection of the cells against human corona virus. A higher bar indicates higher degree of protection (lowercase letters are significantly different from each other (P< 0.05))	Figure 6 - The effect of the C&C technology (PL-16) in protection of the cells against influenza virus. A higher bar indicates higher degree of protection (lowercase letters are significantly different from each other (P< 0.05))


Figure 7 - The effect of the C&C technology (PL-15) in protection of the cells against SARS-CoV-2 Omicron BA.1 virus. A higher bar indicates higher degree of protection (lowercase letters are significantly different from each other (P< 0.05))