Laura S. Harris brought a medical malpractice action against Samuel D. Murray, Jr., M.D.,1 and filed with her complaint an expert affidavit as required by OCGA § 9-11-9.1. The affidavit showed on its face that the expert executed it under oath before a notary public. In a subsequent deposition, the expert testified that the notary public whose jurat appeared on the affidavit did not administer an oath to him before he signed it. The trial court granted summary judgment in favor of Murray on the basis that Harris failed to comply with the affidavit requirement of OCGA § 9-11-9.1 because without an oath the document was not an affidavit. Harris claims the trial court erred in granting summary judgment to Murray because (1) Murray waived lack of compliance with OCGA § 9-11-9.1 as a defense by failing to raise the defense in his initial responsive pleading; and (2) the affidavit was in fact executed under oath.
1. Prior to discussing the application of OCGA § 9-11-9.1 to the facts of this case, we must first determine which version of the statute applies. The present action was filed on December 14, 1995. In 1997, the legislature amended § 9-11-9.1 with an effective date of July 1, 1997. Ga. L. 1997, pp. 916, 919, § 2. Section 2 of the 1997 amendments provided that the 1997 act “shall apply only to actions *662filed on or after [the effective] date.” Id. Accordingly, the legislature expressed its intention that the 1997 amendments apply prospectively.
In Vester v. Mug A Bug Pest Control, 231 Ga. App. 644 (500 SE2d 406) (1998), this Court recognized that § 9-11-9.1 is a statute governing procedural rather than substantive matters; that the effective date of the 1997 amendments to § 9-11-9.1 was July 1,1997, and that the legislature provided in Section 2 of the amendments that the 1997 act “ ‘shall apply only to actions filed on or after (the effective) date.’ ” Id. at 649. Despite the above-quoted language indicating prospective application of the 1997 amendments, Vester concluded that: “Such language is applicable only to laws that create substantive rights that cannot be given retroactive effect, because the parties are vested with substantive rights. See OCGA § 1-3-5; Polito v. Holland, 258 Ga. 54 (365 SE2d 273) (1988); Pritchard v. Savannah Street &c. R. Co., 87 Ga. 294 (13 SE 493) (1891). This Court has held that OCGA § 9-11-9.1 is procedural in nature, conveying no vested rights, and can be applied retroactively. Kneip v. Southern Engineering, 260 Ga. 409, 410-411 (4) (395 SE2d 809) (1990); Blackmon v. Thompson, 195 Ga. App. 589 (394 SE2d 795) (1990); Precision Planning v. Wall, 193 Ga. App. 331 (387 SE2d 610) (1989). As a procedural law, notwithstanding the legislative attempt to make the application prospective only, the reenactment has retroactive application.” Id.
The above-quoted holding in Vester is contrary to long established law, subverts the clear legislative intent for prospective application of the 1997 amendments, and we therefore overrule it. The correct rule is that “where a statute governs only procedure of the courts, including the rules of evidence, it is to be given retroactive effect absent an expressed contrary intention. Pritchard v. The Savannah Street &c. Co., 87 Ga. 294 (13 SE 493) (1891); Slaughter v. Culpepper, 35 Ga. 25 (1866).” (Emphasis supplied.) Polito v. Holland, 258 Ga. at 55. The legislature expressed its intention that the 1997 amendments to § 9-11-9.1 be given prospective application by plainly stating that the 1997 act “shall apply only to actions filed on or after [the effective] date.” Ga. L. 1997, pp. 916, 919, § 2. Vester incorrectly cited Pritchard, 87 Ga. 294 and Polito, 258 Ga. 54 for the proposition that only statutes creating substantive rights can be given prospective application. In fact, these cases recognize the power of the legislature to give prospective application to procedural statutes by expressing a legislative intention to do so. Vester also misleadingly cites Kneip, 260 Ga. 409; Blackmon, 195 Ga. App. 589, and Precision Planning, 193 Ga. App. 331, in support of its conclusion that the 1997 amendments apply retroactively. Although these cases correctly concluded that § 9-11-9.1 is procedural and that the statute applied retroactively, all three cases dealt with the 1987 version of the stat*663ute and its 1989 amendment. Contrary to the 1997 amendments to § 9-11-9.1, neither the 1987 version of the statute nor the 1989 amendment contained any expression by the legislature that they were to be given prospective application. Ga. L. 1987, pp. 887, 889-890, § 3; Ga. L. 1989, pp. 419, 421-422, § 3. Accordingly, the 1997 amendments to OCGA § 9-11-9.1 do not apply retroactively to this case; rather, the former version of the statute controls.
2. We find no merit in Harris’ contention that Murray waived his defense under OCGA § 9-11-9.1.
Murray’s defense under § 9-11-9.1 was that the expert affidavit, which appeared valid on its face when it was filed with the complaint, was subsequently shown not to be an affidavit because it was not given under oath. Murray raised this defense after the expert testified on deposition that no formal oath was administered to him when he executed the affidavit.
Prior to the 1997 amendments to § 9-11-9.1, former subsection (e) of the statute provided in pertinent part that: “Except as allowed under subsection (b) of this Code section, if a plaintiff fails to file an affidavit as required by this Code section contemporaneously with a complaint alleging professional malpractice and the defendant raises the failure to file such an affidavit in its initial responsive pleading, such complaint is subject to dismissal for failure to state a claim and cannot be cured by amendment pursuant to Code Section 9-11-15. . . .” In Seely v. Loyd H. Johnson Constr. Co., 220 Ga. App. 719, 724 (470 SE2d 283) (1996), we construed former subsection (e) in a case where the malpractice plaintiff failed to file any document purporting to be the required expert affidavit with the complaint, and the malpractice defendant did not raise this failure as a defense in its initial responsive pleading. On these facts, we concluded that under the plain language of the statute, the defendant’s failure to raise the lack of an affidavit in its initial responsive pleading was a waiver of the defense. Id. at 724.
The waiver holding in Seely is inapplicable to the present facts. Because Harris filed a document with the complaint which appeared on its face to be a valid expert affidavit in compliance with OCGA § 9-11-9.1, Murray initially had no reason to challenge the affidavit and, therefore, he had no duty under the statute to raise any § 9-11-9.1 defense in his initial responsive pleading to the complaint. When Murray subsequently deposed the expert, the expert testified that no formal oath was administered to him before he executed the affidavit. Upon making this discovery, Murray’s first response was to file motions seeking dismissal or summary judgment on the complaint in which he raised the defense that Harris failed to file the required affidavit. Under these facts, there was no waiver of the § 9-11-9.1 defense. Because Murray acted diligently in raising the defense in *664the first pleading he filed after discovering evidence causing him to challenge the validity of the affidavit, he satisfied the statutory requirement that the defendant raise the failure to file the required affidavit “in its initial responsive pleading.” OCGA § 9-11-9.1 (e), (f); Phoebe Putney Mem. Hosp. v. Skipper, 226 Ga. App. 585, 586 (487 SE2d 1) (1997) (physical precedent), cert, granted by the Supreme Court and remanded to the Court of Appeals in unpublished order (1998).
This conclusion comports with our duty to construe the statute in a manner that gives effect to the intention of the legislature. City of Roswell v. City of Atlanta, 261 Ga. 657 (410 SE2d 28) (1991). Although the statute does not plainly address its application to the present facts, the legislature clearly intended to allow the defendant in a malpractice case to raise the failure to file the required expert affidavit at the defendant’s first opportunity. Murray’s first opportunity to file a responsive pleading raising the defense was not in his initial responsive pleading after the complaint, but in his initial responsive pleading after the deposition in which it was revealed that no formal oath was administered. To construe the statute under these facts to mean that defendants waive the defense unless they preserve it by raising it in their initial responsive pleading to the complaint would require defendants to universally raise possible defenses in response to the complaint without any factual basis at the time for doing so. The legislature could not have intended this result because it would place defendants attempting to preserve the defense in violation of the requirements of honesty and good faith in pleading and would subject them to possible abusive litigation claims. North Ga. Production Credit Assn. v. Vandergrift, 239 Ga. 755, 763 (238 SE2d 869) (1977); OCGA § 51-7-80 et seq.
3. Harris asserts that, contrary to the trial court’s finding, the expert affidavit was given under oath. We agree with this assertion.
“In order to make an affidavit, there must be present the officer, the affiant, and the paper, and there must be something done which amounts to the administration of an oath.” Carnes v. Carnes, 138 Ga. 1, 6 (74 SE 785) (1912). It is not necessary that the oath administered be formal, nor is it necessary that any exact words or specific ceremony be used to constitute a valid administration of an oath. McCain v. Bonner, 122 Ga. 842, 846 (51 SE 36) (1905); Britt v. Davis, 130 Ga. 74, 77 (60 SE 180) (1908). “What the law requires is that there must be, in the presence of the officer, something done whereby the person to be bound consciously takes upon himself the obligation of an oath. It is not essential that affiant should hold up his hand and swear in order to make his act an oath, but it is sufficient if both affiant and the officer understand that what is done is all that is necessary to complete the act of swearing.” (Citations and punctuation omitted.) *665McCain, 122 Ga. at 846.
In the instant case, although the affiant did not hold up his hand and swear before signing the affidavit, it is uncontroverted that both he and the notary public understood that his actions and signing of the affidavit in the notary public’s presence were all that was necessary to complete the act of swearing. The record shows that in response to Murray’s summary judgment motion, Harris produced additional affidavits from Jeffrey S. Penner, M.D., the expert affiant on the § 9-11-9.1 affidavit, and from Laurette Ross, the notary public before whom Penner appeared to execute the § 9-11-9.1 affidavit.
Ross stated in her affidavit that “[o]n December 11,1995, Jeffrey S. Penner, M.D., appeared before me in order to execute an [expert] Affidavit to be given in [this case]. By his actions, I understood that he considered himself to be under oath when he executed the Affidavit.” Similarly, Penner stated in his second affidavit that “[o]n December 11, 1995,1 executed the document labeled Affidavit of Jeffrey S. Penner, M.D (hereinafter referred to as ‘First Affidavit’). At the time of executing the First Affidavit, I was standing before Laurette Ross, the notary public. As recited in the First Affidavit, I knew the document I was signing was intended to be an affidavit. I did consciously, in the presence of the notary, take upon myself the obligations of the oath. I intended all of the statements made in the First Affidavit to be truthful and understood myself to be under oath.”
Contrary to Chief Judge Andrews’ dissent, the evidence shows more than that Penner merely signed a document. The affidavit Penner signed clearly stated it was being made under oath, and Penner has said that he read and understood that it was being made under oath before he signed it. Furthermore, the signing was done in front of the notary public and she has sworn that by Penner’s actions she understood that he considered himself to be under oath when executing the affidavit. Because Penner signed the affidavit in front of Ross and because they both understood that what he had done was sufficient to complete the act of swearing, we must conclude that the affidavit was given under oath and is valid.
The dissent contends that this conclusion virtually eliminates the requirements for a valid oath set forth in McCain, supra, Britt, supra, and Carnes, supra. This contention is without merit. All three of those cases involved affidavits signed by affiants outside the presence of officers who later signed the affidavits. In both Carnes and Britt the Supreme Court found that affidavits signed by affiants outside the presence of the officers were invalid. In McCain, supra at 846, the Court determined that there was evidence the previously signed affidavit was valid when the affiant presented it to the officer, the affiant swore the affidavit was true, and then the officer signed *666the jurat. Our holding in the instant case, that the affidavit was valid because Penner signed it in front of Ross and they both understood that he was under oath, falls squarely under the authority of Carnes, Britt and McCain.
Moreover, this holding comports with the expressed intention of the legislature and our Supreme Court that the affidavit requirement be liberally construed in favor of the plaintiff and that amendment of the affidavit should be allowed to make it comport with OCGA § 9-11-9.1. “Because OCGA § 9-11-9.1 constitutes an exception to the general liberality of pleading allowed under the Civil Practice Act, it is to be construed in a manner consistent with the liberality of the Act so long as such a construction does not detract from the purpose of § 9-11-9.1, which is to reduce the filing of frivolous malpractice suits.” Porquez v. Washington, 268 Ga. 649, 652 (492 SE2d 665) (1997). “[A] § 9-11-9.1 affidavit should be construed most favorably to the plaintiff with all doubts resolved in plaintiffs favor, even if an unfavorable construction of the affidavit may be possible.” Id. at 650. See also Gadd v. Wilson &c., 262 Ga. 234, 235 (416 SE2d 285) (1992). Moreover, when the sufficiency of the expert affidavit initially filed with the complaint is challenged, a plaintiff is allowed to present supplementary evidence in support of its sufficiency. Hewett v. Kalish, 264 Ga. 183, 184-185 (442 SE2d 233) (1994); Porquez, 268 Ga. at 651-652. This is true whether the challenge is to the expert’s competency or to the sufficiency of the expert’s statements regarding negligent acts. Id. As the Supreme Court stated in Porquez, “[pjermitting the plaintiff to amend the expert affidavit in order to meet the requirement that it set forth at least one claimed negligent act or omission by each defendant and its factual basis does not defeat the purpose of the statute, but instead helps to insure that the complaint is not frivolous.” Id. at 652. The court in Porquez also concluded that the Legislature intended for plaintiffs to have a broad right to amend defective affidavits under former § 9-11-9.1. Id. at 652. In support of this conclusion, Porquez pointed out that the 1997 amendment to § 9-11-9.1 provides in subsection (d) that if the defendant alleges by motion filed with the initial responsive pleading that the expert affidavit filed with the complaint is defective, the plaintiff may cure the alleged defect by amendment pursuant to OCGA § 9-11-15 within 30 days of service of the motion. Id.2
In this case Harris clearly fulfilled the intent behind OCGA § 9-11-9.1 to thwart the filing of frivolous lawsuits by filing an expert affidavit, given under oath, that clearly states an act of professional *667negligence by the defendant Murray. The trial court’s grant of summary judgment to Murray was erroneous and must be reversed.
Judgment reversed.
Johnson, P. J., Beasley, Blackburn, Smith, Ruffin, JJ, and Senior Appellate Judge Harold R. Banke concur. McMurray, P. J, and Eldridge, J, concur specially. Andrews, C. J, dissents.The complaint also names other defendants who are not parties to this appeal.
Of course, this newly created 30-day right to cure alleged defects does not apply in the present case since, as previously stated, the 1997 amendments have no application here.