I
We first consider appellants’ contention that federal law does not preempt state law concerning the liability of vaccine manufacturers for deaths or injuries caused by their products.
Under the Supremacy Clause of the United States Constitution, state laws that interfere with or are contrary to federal laws on a given subject are a nullity. E.g., Gibbons v. Ogden (1824), 22 U.S. (9 Wheat.) 1, 210-211. Although this court would not ordinarily reach this constitutional question unless there were a need to do so, we find this question has been well-settled. Congress itself has clearly expressed its intention not to preempt liability claims against vaccine manufacturers under state law, by stating in the National Childhood Vaccine Injury Act that “* * * State law shall apply to a civil action brought for damages for a vaccine-related injury or death.” Section 300aa-22(a), Title 42, U.S. Code. Furthermore, all federal courts that have addressed the issue have concluded that there is no federal preemption of state tort or contract remedies against vaccine manufacturers. See, e.g., Abbot v. American Cyanamid Co. (C.A. 4,1988), 844 F. 2d 1108, 1113-1114, certiorari denied (1988), 488 U.S___, 102 L. Ed. 2d 248, 109 S. Ct. 260.3 Accordingly, Wyeth’s liability for Tyler’s injuries may be determined under Ohio law.
*394In Temple v. Wean United, Inc. (1977), 50 Ohio St. 2d 317, 4 O.O. 3d 466, 364 N.E. 2d 267, this court approved and adopted Section 402A of 2 Restatement of the Law 2d, Torts (1965) 347-348, as the law of Ohio with respect to strict products liability. That section provides:
“(1) One who sells any product in a defective condition unreasonably dangerous to the user or consumer or to his property is subject to liability for physical harm thereby caused to the ultimate user or consumer, or to his property, if
“(a) the seller is engaged in the business of selling such a product, and “(b) it is expected to and does reach the user or consumer without substantial change in the condition in which it is sold.
“(2) The rule stated in subsection (1) applies although
“(a) the seller has exercised all possible care in the preparation and sale of his product, and
‘ ‘(b) the user or consumer has not bought the product from or entered into any contractual relation with the seller.”
In Seley v. G.D. Searle & Co. (1981), 67 Ohio St. 2d 192, 21 O.O. 3d 121, 423 N.E. 2d 831, this court also recognized that Comment k to Section 402A provides the following exception to the strict liability of manufacturers for injuries caused by defective products:
“Unavoidably unsafe products. There are some products, which, in the present state of human knowledge, are quite incapable of being made safe for their intended and ordinary use. These are especially common in the field of drugs. An outstanding example is the vaccine for the Pasteur treatment of rabies, which not uncommonly leads to very serious and damaging consequences when it is injected. Since the disease itself invariably leads to a dreadful death, both the marketing and the use of the vaccine are fully justified, notwithstanding the unavoidably high degree of risk which they involve. Such a product, properly prepared, and accompanied by proper directions and warning, is not defective, nor is it unreasonably dangerous. The same is true of many other drugs, vaccines, and the like, many of which for this very reason cannot legally be sold except to physicians, or under the prescription of a physician. It is also true in particular of many new or experimental drugs as to which, because of lack of time and opportunity for sufficient medical experience, there can be no assurance of safety, or perhaps even of purity of ingredients, but such experience as there is justifies the marketing and use of the drug notwithstanding a medically recognizable risk. The seller of such products, again with the qualification that they are properly prepared and marketed, and proper warning is given, where the situation calls for it, is not to be held to strict liability for unfortunate consequences attending their use, merely because he has undertaken to supply the public with an apparently useful and desirable product, attended with a known but apparently reasonable risk.” (Emphasis sic.) 2 Restatement of the Law 2d, Torts, supra, at 353-354.
Thus, under Comment k, a manufacturer of an unavoidably unsafe product may not be held strictly liable for injuries caused thereby, provided that the product was “* * * properly prepared, and accompanied by proper directions and warning * * *.”4 Id. We now turn to a consideration of the ap*395plicability of Comment k in the case sub judice.
II
Appellants next contend that Comment k does not apply as a matter of law to all prescription drugs and vaccines. The language of the comment is somewhat unclear on this point, but the following reasoning by the Supreme Court of Idaho in Toner v. Lederle Laboratories (1987), 112 Idaho 328, 339, 732 P. 2d 297, 308, is persuasive:
“The comment refers to ‘some’ products which are unavoidably unsafe; the comment states such products are ‘especially common in the field of drugs’; the comment cites certain examples from that field deserving of its protection and notes that ‘[t]he same is true of many other drugs, vaccines, and the like * * * [and] of many new and experimental drugs * * *.’ (Emphasis added.) Obviously the comment does not apply to all drugs. * * * It is equally obvious that not all drugs are so perfectly designed that they cannot be made more pure or more safe, or that there are not safer, suitable alternatives; nor [sic] do the benefits of all drugs necessarily outweigh their risks.” (Emphasis sic.) Accord Senn v. Merrell-Dow Pharmaceuticals, Inc. (1988), 305 Ore. 256, 263, 751 P. 2d 215, 218-219, at fn. 4; Graham v. Wyeth Laboratories (D. Kan. 1987), 666 F. Supp. 1483, 1496.
Accordingly, we hold that a prescription drug, vaccine, or like product is not “unavoidably unsafe” per se under Comment k to Section 402A of 2 Restatement of the Law 2d, Torts, supra. Whether such a product qualifies as “unavoidably unsafe” under Comment A; is a determination to be made on a case-by-case basis.
Ill
Appellants further maintain that the DTP marketed by appellee at the time it was administered to Tyler was not unavoidably unsafe, and that therefore appellee is not entitled to the protection of Comment k.
Unavoidably unsafe products are defined by Comment k as those “* * * which, in the present state of human knowledge, are quite incapable of being made safe for their intended and ordinary use.” 2 Restatement of the Law 2d, Torts, supra, at 353. It follows, then, that a product is unavoidably unsafe if, at the time of its distribution, there existed no alternative design which would have as effectively accomplished the same purpose or result with less risk. See Toner v. Lederle Laboratories, supra, at 337, 732 P. 2d at 306; Kearl v. Lederle Laboratories (1985), 172 Cal. App. 3d 812, 830, 218 Cal. Rptr. 453, 464.5
A
Appellants urge that Wyeth could have marketed a DTP containing a fractionated cell pertussis vaccine at the time in question. However, we find that the record does not support this contention.
At the time of the events pertaining to this case, all the licensed private companies and state health departments producing DTP in this country used a whole cell pertussis vaccine. Neither the Lilly fractionated cell vaccine nor the acellular vaccine developed in Japan was licensed by the *396FDA to any manufacturer for production or marketing in the United States during this period.
Thus, appellee was not licensed by the FDA to manufacture DTP containing either a fractionated cell or an acellular pertussis vaccine at the time Tyler was immunized. As a result, appellee was prohibited by federal law from employing either of these vaccines in its DTP. See Sections 262(a) and (d), Title 42, U.S. Code; Sections 331(d) and 333(a), Title 21, U.S. Code.
In addition, there is nothing in the record that suggests that, at the time in question, appellee could have marketed a safer design of DTP. By 1982, a year prior to Tyler’s DTP vaccination, appellee had developed a DTP design based on Lilly’s Trisolgen, which utilized a fractionated cell pertussis vaccine. However, the FDA did not grant appellee the license amendment necessary for appellee to market its redesigned DTP. In rejecting the DTP design proposed by appellee, the FDA apparently expressed, inter alia, the need for several design improvements, the fact that there had been two adverse reactions to the proposed vaccine during clinical trials, and the fact that there was no conclusive evidence that it was any more effective than DTP made with a whole cell pertussis vaccine. Faced with this defeat, appellee decided to follow the FDA’s suggestion that it seek to develop a DTP design based on an acellular pertussis vaccine instead of trying to correct the problems with the proposed vaccine. In view of the foregoing, it was not possible for appellee to have legally marketed a DTP design using a fractionated cell pertussis vaccine at the time Tyler was inoculated. At the time of Tyler’s immunization, appellee had purchased an acellular pertussis vaccine from a Japanese company in order to initiate a new DTP study and come up with a safer vaccine.
B
Appellants also allege that there is evidence that DTP containing a fractionated cell or acellular pertussis vaccine would be both effective and safer than DTP made with a whole cell pertussis vaccine. We find this evidence to be speculative at best.
Initially, there remains an unsettled question as to whether the pertussis component of DTP is responsible for the more serious adverse reactions that have been temporally associated with DTP vaccinations. At trial, an expert testified that studies have been made comparing the adverse effects following immunization with DTP with those following immunization with DT (a vaccine comprised solely of diphtheria and tetanus components). The results of these studies suggest that the only difference between the adverse effects of the two vaccines is that DTP more frequently causes crying and fever.
There is also a lack of consensus in the scientific community both as to whether endotoxin and pertussis toxin are necessary components of an effective pertussis vaccine, and as to what effects these toxins have on the nervous system.6 Therefore, there is no conclusive evidence that a fractionated cell vaccine is safer because most of its endotoxin has been removed, or that an acellular pertussis vaccine is safer because not only has most of its endotoxin been removed, but also its pertussis toxin has been inactivated to some extent.
Moreover, no conclusive evidence *397was adduced at trial indicating that DTP made with a fractionated cell or an acellular pertussis vaccine would be as or more effective than DTP containing a whole cell pertussis vaccine. In fact, no side-by-side comparisons of the relative efficacy of these vaccines have ever been made. It is worth noting, however, that at the time of trial herein, a field trial of two Japanese acellular pertussis vaccines was being conducted in Sweden to demonstrate their efficacy.
C
In sum, there is no support in the record for appellants’ contention that appellee’s DTP is not an unavoidably unsafe product. At the time that the DTP marketed by appellee was administered to Tyler, appellee could not have legally marketed DTP containing an alternative pertussis vaccine that would have immunized children against whooping cough just as effectively but with less risk.
IV
Finally, appellants contend that appellee failed to provide adequate warning with its DTP, and that therefore appellee may be held strictly liable under Comment k.
During the period relevant to this suit, every vial of appellee’s DTP was packaged with an insert which set forth the following warning:
“Side Effects and Adverse Reactions
* *
“The below-listed serious, and occasionally fatal, adverse reactions have been reported following administration of pertussis-vaccine-containing preparations. The incidence of these reactions is unknown, but they seem to be exceedingly rare. Should such reactions occur, further immunization against pertussis is contraindicated. * * * See also Contraindications and Precautions.
“1. Severe temperature elevations — 105° or higher.
“2. Collapse with rapid recovery.
“3. Collapse followed by prolonged prostration and shock-like state.
“4. Screaming episodes characterized by a prolonged period of peculiar crying during which the infant cannot be comforted.
“5. Isolated convulsion(s) with or without fever.
“6. Frank encephalopathy with changes in the level of consciousness, focal neurological signs, and convulsions with or without permanent neurological and/or mental deficit.4-9 * *
The footnotes in Item 6 of the above-quoted material provided full citations to articles published in accessible medical journals which contained detailed discussions of the nature and reported rates of occurrence of events which were temporally related to the use of DTP:
“4. TOOMEY, J.A.: Reactions to pertussis vaccine. J. Am. Med. Assoc. 139-MS, 1949.
“5. BYERS, B.K., MOLL, F.C.: Encephalopathies following prophylactic pertussis vaccine. Pediatrics 1: 437, 1948.
“6. BERG, J.: Neurological complications of pertussis immunization. Brit. Med. J. 2:24, 1958.
“7. STROM, J.: Further experience of reactions, especially of a cerebral nature, in conjunction with triple vaccination: A study based on vaccinations in Sweden, 1959-65. Brit. Med. J. .4:320, 1967.
“8. STEWART, G.: Vaccination against whooping cough. Efficacy versus risks. Lancet 1: 234, 1977.
“9. KULENKAMPFF, M. et al.: Neurological complications of per*398tussis inoculation. Arch. Dis. Child. ¿0:46, 1974.”
In Seley v. G.D. Searle & Co., supra, at paragraph two of the syllabus, we held that a manufacturer of an unavoidably unsafe prescription drug provides adequate warning when “* * * it reasonably discloses all risks inherent in the use of the drug of which the manufacturer, being held to the standards of an expert in the field, knew or should have known to exist.” We further held that the manufacturer of a prescription drug “* * * satisfies its duty to warn of risks associated with the use of the product by providing adequate warnings to the medical profession and not to the ultimate user.” Id. at paragraph five of the syllabus.
Herein, the court of appeals concluded that the evidence overwhelmingly demonstrated the adequacy of appellee’s warning, and that the trial court should have directed a verdict in favor of appellee on this issue. We agree. All the testimony at trial supported the proposition that the warning was adequate, and perhaps even overly inclusive. Additionally, it was undisputed that the FDA had reviewed and given its approval to the warning in the package insert. Reasonable minds could only conclude that the warning was adequate, and therefore the issue should not have been submitted to the jury.
Taking all the foregoing into consideration, we hereby affirm the judgment of the court of appeals.7
Judgment affirmed. Moyer, C.J., Holmes and Wright, JJ., concur. H. Brown, J., concurs separately. Sweeney and Douglas, JJ., concur in part and dissent in part.See, also, Hurley v. Lederle Laboratories (C.A. 5, 1988), 851 F. 2d 1536; Knudson v. United States (M.D. Fla. 1987), 691 F. Supp. 1346; Foyle v. Lederle Laboratories (E.D. N.C. 1987), 674 F. Supp. 530; Martinkovic v. Wyeth Laboratories (N.D. Ill. 1987), 669 F. Supp. 212; Morris v. Parke, Davis & Co. (C.D. Cal. 1987), 667 F. Supp. 1332; MacGillivray v. Lederle Laboratories (D. N.M. 1987), 667 F. Supp. 743; Graham v. Wyeth Laboratories (D. Kan. 1987), 666 F. Supp. 1483; Wack v. Lederle Laboratories (N.D. Ohio 1987), 666 F. Supp. 123; Patten v. Lederle Laboratories (D. Utah 1987), 655 F. Supp. 745.
Comment k does not, however, provide the manufacturer of such a product with a defense against a claim of negligence. See Toner v. Lederle Laboratories *395(1987), 112 Idaho 328, 336, 732 P. 2d 297, 305; Feldman v. Lederle Laboratories (1984), 97 N. J. 429, 442, 479 A. 2d 374, 381; Graham v. Wyeth Laboratories (D. Kan. 1987), 666 F. Supp. 1483, 1497.
Kearl v. Lederle Laboratories, supra, was recently disapproved in Brown v. Superior Court (1988), 44 Cal. 3d 1049, 245 Cal. Rptr. 412, 751 P. 2d 470.
Indeed, one of appellants’ expert witnesses, Dr. Geraghty, testified that there was no guarantee that Tyler would not have had the same adverse reaction if he had been injected with DTP containing a fractionated cell pertussis vaccine.
In view of the outcome of this case, we do not find it necessary to address appellants’ contention that the trial court erred in denying their motion for prejudgment interest without first holding a hearing.