Assisted reproduction techniques help thousands of couples with infertility to circumvent their problem and become parents. Nevertheless, when it is not possible for a woman to conceive due to poor egg quality or from having no eggs at all, she may still become pregnant by using eggs from a donor.

The first pregnancy with egg donation was reported in 1983, and ever since, more and more women are choosing this procedure to achieve their dream of having children. The main reason for this trend is that women are increasingly postponing childbearing until later on in life, when their fertility is often reduced; another reason is that over the years, the process has become highly successful due to recent technologies advances and improved freezing techniques.

What is egg donation?

Egg donation is a form of assisted reproduction by which a woman donates her ova to enable another woman to conceive. These oocytes are fertilized by the recipient’s husband sperm, or alternatively by a donor sperm.

The resulting embryos are transferred into the recipient uterus, which has been adequately prepared to receive them. The difference with routine in vitro fertilization (IVF) is that the egg donor is not the recipient; that is, they are two different women.

If pregnancy occurs, the recipient will have a biological but not a genetic relationship to the child, and her partner (if he provided the sperm) will be both biologically and genetically related.

What are the indications for egg donation?

Egg donation may be considered in the following situations:

  • Premature ovarian insufficiency: a condition in which menopause begins earlier than usual, usually before the age of 40 years old. In most cases the cause is unknown, but it may be the result of certain diseases, chemotherapy, radiotherapy or surgical removal of the ovaries. Egg donation is also suitable for women who were born without ovaries.
  • Low ovarian reserve: when there is a decrease in the number of eggs, resulting in reduced chances of pregnancy. Generally, this is due to advanced reproductive age, as the number of oocytes -and therefore fertility- decreases rapidly after the age of 35-40 years old.
  • Genetically transmitted diseases: women affected by, or carriers of a significant genetic disease who would prefer not to pass this disease on to their child.
  • Previous history of failure with IVF: especially when egg quality seems to be the problem.

Who are the egg donors?

1) Anonymous, voluntary donors: According to the Greek law, candidate egg donors are covered by anonymity and are required to sign a specific consent for the donation of their genetic material. In order to accept a woman into an egg donation program she should meet the following requirements:

  • Age between 18 and 35 years old.
  • She should be healthy, non-smoker, with no personal or family history of genetic diseases.

By law, the donor receives financial compensation only for the loss of working days, travel and other expenses incurred during the treatment cycle in which she participates. In any case, egg donation is an altruistic, anonymous and voluntary act.

2) Egg sharing: Women undergoing IVF may agree to donate their surplus oocytes to other women with infertility.

3) Known donor: a person who is known to the recipient, usually a close relative of friend. According to the Greek law, oocyte donation is an anonymous procedure, that is, the donor has no access to the child born, nor the recipient to the donor. Therefore, in Greece the donation of ova to known persons is forbidden by law.

Evaluation of the egg donor

Each candidate donor, after being fully informed about the egg donation program, completes a thorough questionnaire on her family, medical and psychological history. In addition, she is the subject of a series of exams to determine whether her health is in good condition and she can respond properly to the hormonal therapy.

The evaluation involves a comprehensive physical and gynecological examination, as well as the assessment of her psychological and mental status, her genetic material and reproductive system.

In addition, donors undergo the following laboratory testing:

  • Blood type and Rhesus
  • Hepatitis B & C
  • HIV 1 & 2
  • Syphilis
  • Hemoglobin electrophoresis
  • Sickle cell trait testing
  • Cystic fibrosis (CF) mutation
  • Fragile X testing
  • Conventional karyotype. It is also possible to a perform a molecular karyotype, upon request of the recipient couple.

A donor is ineligible if either the questionnaire or the screening tests indicate the presence of risk factors, or clinical evidence of an infectious or genetic disease.

Evaluation of the recipient couple 

Adequate screening and preparation of the recipient couple are essential for the success of an egg donation program.

According to the Greek law, a woman is considered suitable to receive oocytes when her uterus has normal morphology and functionality and has not exceeded the age of 50 years.

The evaluation of the recipient couple is similar to that of couples undergoing routine IVF. First, the physician obtains a thorough medical history from both partners.

The assessment of the woman includes an in-depth physical and gynecological examination, a detailed pelvic ultrasound and laboratory testing. Briefly, the ovarian function, her blood group, and exposure to certain infections are examined. In addition, a Pap smear test and cultures for certain microbes (Neisseria gonorrhoeae, Chlamydia trachomatis, etc) are obtained.

In some cases, the uterine cavity is evaluated with hysterosalpingography (HSG), sonohysterography or hysteroscopy. If the woman is over 45 years old, a more thorough assessment of her cardiac function, pregnancy-induced hypertension and gestational diabetes risk are recommended. The effect of advanced maternal age on pregnancy will be discussed extensively, as well as any medical conditions that may affect pregnancy.

An embryo transfer trial before the actual procedure (“mock” embryo transfer) is strongly recommended. It allows to determine the best way to place the embryos into the uterus, and ensures that there are no unexpected obstacles along the way. Sometimes the cervix is very narrow and hinders the transfer of the embryos into the uterus; this may result in significantly reduced chances of pregnancy. In case of a narrow or distorted cervical canal, a cervical dilation may be recommended.

A treatment trial in a previous cycle with the same medications used for the endometrial preparations is proposed when possible, in order to assess the uterine response to hormone therapy.

The male assessment includes a semen analysis, blood group and genetic testing, among other exams.

According to the Greek law, the recipient couple should be tested for syphilis, hepatitis B and C, HIV-1 and HIV-2 within the six months preceding the treatment cycle.

The procedure

Preparation of the donor for egg retrieval 

The donor follows the procedure of a standard IVF. Initially, she undergoes ovarian stimulation, that is, she receives a combination of hormonal medications in order to achieve the development of a sufficient number of oocytes within the ovaries; egg development is monitored by ultrasound and blood exams at regular intervals. When the oocytes are at the appropriate size, ovulation is triggered by an injection of human chorionic gonadotropin (hCG). Oocyte retrieval, scheduled approximately 34-36 hours after hCG administration, entails the use of a needle which is inserted through the vagina into the ovaries, whereby the eggs are aspirated under ultrasound guidance. The procedure is carried out under a mild sedation.

The ova obtained are evaluated for their maturity and then fertilized with the partner’s sperm, which has been processed in the laboratory. Donor sperm may be also utilized when indicated.

The male partner should provide the semen sample the day of the donor’s egg retrieval. Alternatively, if the presence of the partner is not possible on that day, the semen can be cryopreserved (frozen) at an earlier time.

Preparation of the recipient for embryo transfer

In order for the embryos to implant into the recipient’s uterus, the endometrium (uterine lining) must be prepared and synchronized with the donor cycle.

There are numerous protocols for endometrial preparation. Briefly, women who still have menstrual period may receive an injectable medication for temporary suppression of the ovarian function. When the donor starts ovarian stimulation, the recipient receives a hormone called estradiol to achieve endometrial growth. Estradiol can be administered orally or through a transdermal patch. Ultrasound assessment of endometrial thickness -and occasionally blood tests- are performed during this period. On the day after the donor receives hCG, the recipient begins treatment with progesterone. Progesterone causes endometrial maturational changes that allow the embryo to implant. Progesterone can be administered by intramuscular injection, vaginally or orally. Besides estradiol and progesterone, other medications may be prescribed if required.

The embryos are transferred into the recipient’s uterus, usually within three to five days after fertilization of the eggs in the laboratory. Embryo transfer is done using a thin catheter inserted through the cervix into the uterus. If the recipient couple has extra embryos, they will be cryopreserved (frozen). Thus, it is possible to transfer these embryos at a later time without the need for another egg donation.

Hormonal therapy with estradiol and progesterone continues until the recipient takes a blood pregnancy test (β hCG). If the test is positive, the hormones are continued during the first trimester of pregnancy.

Success rates with egg donation

Since egg donors are young and healthy women, success rates are higher than those obtained with conventional IVF. The age of the recipient does not seem to affect the success of the procedure. According to data from the National Agency of Medically Assisted Reproduction, the pregnancy rate with egg donation in Greece is 54%.

Nevertheless, the greater the number of attempts with donor-egg IVF, the higher the odds of success. Thus, it is estimated that the success rates after the third attempt reach almost 90% in most cases.

Many factors play an important role in the success of the procedure: adequate evaluation and preparation of both donors and recipients, optimal synchronization between them, high laboratory standards and well-trained scientific staff, will all have a positive impact on pregnancy rates in an egg donation program.

Risks of egg donation 

1) For the donor:

Egg donation is a very safe procedure. Nevertheless, it is not entirely risk-free. Medicines taken to stimulate the ovaries, oocyte retrieval and the anesthesia required are all possible sources of complications. Briefly, the side effects of medications are usually mild, as one of the most feared complications in assisted reproduction, ovarian hyperstimulation syndrome is very rare in these cases. The remaining risks are estimated as follows: anesthesia risks: 1 / 10,000; risk of severe bleeding from oocyte retrieval: 1 / 2,500; risk of infection: less than 1/500.

It should be noted that the fertility of women who become egg donors is in no way affected. In fact, the eggs donated would have been otherwise discarded by their bodies.

2) For the recipient:

The possibility a donor transmits an infectious disease to the recipient is virtually non-existent, provided that proper evaluation of the egg donor has been performed, as dictated by the Greek law.

The most common risk for the recipient is the occurrence of a multiple pregnancy (twins) if more than one embryo is transferred. In any case, in egg donation cycles, the transfer of more than two embryos is strictly forbidden by the Greek law. If the couple is opposed to the possibility of a twin pregnancy, then only one embryo may be transferred (single embryo transfer, SET).

Pregnancy complication risk in recipiens with advanced age should be assessed individually for each case.

3) For the child:

To date, thousands of children have been born with this procedure, and the available data is reassuring, and equivalent to that of conventional IVF: the rate of birth defects is the same as the general population.


On Egg Donation

  • Egg donation is an altruistic act, voluntary and with no financial benefit. Donors are compensated only for the working days they lose as part of the donation process and their travel expenses.
  • Donation of ova and sperm is allowed in Greece provided donor anonymity is ensured.
  • Egg donation is not allowed to women over 50 years old.
  • Donors must sign an oocyte concession consent.
  • Recipients sign a document stating that they are married and accept to undergo in vitro fertilization with egg donation. If they are not married, they should sign a notary act stating that they wish to undego IVF using the egg donation method.

On Assisted Reproduction

On January 27 2005, the law 3305/2005 on the application of assisted reproduction techniques was reported.

The Greek law on medically assisted reproduction is one of Europe’s most flexible. It safeguards the couple who wants to have a child based on medical, biological and bioethical principles. Its main purpose is, ultimately, the protection of the child to be born.

Basic principles of the current legislation

Some of the key points of the in-force law are the following:

1) Assisted reproduction methods are legal and allowed for women up to the age of 50 years, as this is considered the limit for natural conception.

2) The donation of ova and sperm is permitted, but the consent of the spouse or partner is also required.

3) Pre-implantation genetic diagnosis is allowed with the purpose of diagnosing whether the resulting embryos are carriers of genetic diseases. Consent of the concerned individuals is required.

4) Sex selection is prohibited unless a serious sex-related hereditary disease is avoided.

5) Cloning for reproductive purposes is prohibited.

6) Cryopreservation of genetic material or fertilized eggs is permitted.

7) The use of a gestational carrier (surrogacy) is allowed. A surrogate is a woman who carries a pregnancy for another couple or woman, who wishes to have a child but is unable to get pregnant for medical reasons. The surrogate woman must undergo medical and psychological examination. There should be no financial transaction other than the costs resulting from pregnancy exams, loss of work, etc. The procedure requires a special permit from a judge.

8) Assisted Reproduction Units are established and operate with the permission of the competent Authority, which shall give its agreement and verify that the legal requirements are met. For any violation, it sets administrative and criminal penalties.

9) The law sets age limits for sperm donors (younger than 40 years old) and egg donors (younger than 35 years).

10) Single women are allowed to conceive with assisted reproduction.

11) Donors must undergo clinical and laboratory testing and are not admitted to donation programs if they suffer from hereditary, genetic or infectious diseases. The use of fresh semen from donor is not permitted; only frozen semen may be used.


More info at


HPV Vaccine 2 adThis year is the HPV vaccine’s 10th anniversary, as the first cervical cancer vaccine was licensed by the US Food and Drug Administration (FDA) in June 2006. Should we celebrate or not? Arguably the HPV vaccine is one of the most controversial vaccines ever released…

In October 2015 I published the article: “The HPV vaccine controversy: science, media… and marketing”, where I included the information available on the vaccine, focusing on its safety and efficacy. A lot has happened since then, many articles have been published which, instead of clarifying the situation, have rather divided even more both the general public and the scientific community. The result: doctors hesitate to recommend the vaccine, parents and young women are even more confused when they have to decide whether to get vaccinated or not…

In this article I outline the recent events related to the HPV vaccine, focusing on new indications, safety statements and current controversies.


HPV-Associated Cancers are on rise

Malignancies related to HPV include cervical, vulvar, vaginal, penile, oropharyngeal, anal, and rectal cancers.

According to a new report from the USA Centers for Disease Control and Prevention (CDC), HPV-associated cancer incidence have increased from 10.8 per 100,000 persons during 2004–2008 to 11.7 per 100,000 persons during 2008–2012. The most common cancers are cervical and oropharyngeal (although not all oropharyngeal cancers are HPV-related).

The report stresses that a large number of these cancers are associated with the HPV types included in the vaccine, thus vaccination may potentially reduce the incidence of cancer in the future.

The same trend is observed in other countries such as the UK: while the incidence rates of cervical cancer for women aged 25-34 initially decreased by 35% between 1985-1987 and 2000-2002, rates have since increased by 50% in this age group.


More medical societies urge to increase HPV vaccination rates

HPV vaccine 2 ASCODespite many professional organisations recommending HPV vaccination, vaccine uptake in the United States remains low: about 39% of girls and 21% of boys have received the full schedule of HPV vaccines.

Taking into consideration these data, the American Society of Clinical Oncology (ASCO) has recently issued a statement urging to increase vaccination rates. In this article “ASCO stresses (…) the need to increase the proportion of adolescent boys and girls receiving the HPV vaccine (…) which could lead to complete eradication of HPV-related cancers in men and women”. They further emphasize its safety by stating that “Both Gardasil and Cervarix vaccines reported excellent short- and long-term safety results in clinical trials”.

But some issues in the ASCO statement have been questioned, namely the “complete eradication of HPV-related cancers” (as none of the available vaccines is 100% effective), and the “excellent safety results”, as worldwide reports of adolescents with chronic side effects after HPV vaccination continue to be published (see below). In addition, the report does not mention anything about screening tests (Pap smears), which are an indispensable tool for preventing cancer by early detection of precancerous lesions.


Changes in the HPV vaccination schedule

The CDC recently published the new 2016 recommended immunization schedule for children and adolescents. The schedule for HPV vaccination introduces the ninevalent (9vHPV) vaccine for males and females. While females may receive any of the three available vaccine types: 9vHPV (Gardasil 9), 4-valent (Gardasil) or 2-valent (Cervarix), only Gardasil 9 or Gardasil may be used for males.

The CDC also states that HPV vaccine should be administered beginning at age 9 years to children and youth with any history of sexual abuse or assault who have not initiated or completed the 3-dose series.


More studies confirming reduction in the prevalence of HPV, cervical abnormalities and genital warts 

Reduction of HPV prevalence

An American study confirms previous observations of HPV vaccine impact: within 6 years of vaccine introduction, there was a 64% decrease in the four HPV types included in the vaccine among females aged 14 to 19 years and a 34% decrease among those aged 20 to 24 years.

Decrease in condylomas in women and men

In Denmark, girls and young women have been vaccinated since 2008. A recent study shows a significant reduction in the incidence of genital warts, not only in women, but also in men, This means that the vaccine has caused what is called herd immunity. The study concludes: “The reduction is seen in both women up to 35 years of age and men aged 12 to 29 years, suggesting that HPV vaccination is highly efficient and that herd protection has developed.”

Reduction of abnormal Pap tests in high-risk patients

A new study demonstrated the HPV vaccine is effective in a real-world setting of high-risk patients (low-income females, engaging in high-risk sexual behaviors) many of whom had not completed the HPV vaccine schedule.

After following 4127 girls and young women from 11 through 20 years of age who underwent Pap smears, they found that abnormal cytology was less common in vaccinated vs unvaccinated females (8 vs 13 % respectively). The risk was lower if  the 3-dose vaccine series was completed or if the vaccine was administered from 11 through 14 years of age.


The European Medicines Agency concludes HPV vaccine is safe

In my previous article, I mentioned that the European Medicines Agency (EMA) would conduct a safety review of HPV vaccines, mainly due to the numerous reports on severe side effects, not only in lay media, but also in medical journals. The main concern was the occurrence of two particular syndromes, namely complex regional pain syndrome (CRPS) and postural orthostatic tachycardia syndrome (POTS) (see here for more details), suspected to be related with HPV vaccination.

The long awaited EMA review was published in November 2015, and concluded that “the evidence does not support that HPV vaccines (Cervarix, Gardasil, Gardasil 9, Silgard) cause CRPS or POTS. The benefits of HPV vaccines continue to outweigh their risks”. Read their press release here.

After this review, a World Health Organization – Global Advisory Committee on Vaccine safety (GAVCS) Statement on Safety of HPV vaccines followed in December 2015, which declares ” The GACVS has systematically investigated safety concerns raised about HPV vaccines and has issued several reports in this regard. To date, it has not found any safety issue that would alter its recommendations for the use of the vaccine”. The statement refers specifically to CRPS and POTS, but also to the increased incidence of Guillain-Barre syndrome found in a French study (see my previous article).


Danish scientists skeptical about EMA’s conclusions, start independent research

It was Denmark that had requested the safety review of HPV vaccines from the EMA, as this country, with a high vaccine uptake, reported that more than 1300 girls and young women with chronic symptoms (POTS, CRPS) have been referred to specialized centers.

Not convinced with EMA’s conclusion, Denmark is conducting its own investigation into the issue. The Ministry of Heath has given 7 million DKK (US$1.01 million) for research leaded by specialists who are seeing girls with symptoms after HPV vaccination and who are independent of the pharmaceutical industry.


Nordic Cochrane Centre accuses EMA of maladministration and scientific misconduct

HPV vaccine 2 Cochrane NordicRecently, the reputed Nordic Cochrane Centre filed a complaint to the EMA expressing their concern about EMA’s handling of the HPV vaccine safety issue.

The Nordic group says that the EMA report is flawed, and points out several issues. Briefly:

  • The EMA has concluded that there is no causal link between CRPS / POTS and the HPV vaccine, but the Nordic Cochrane group says “The EMA’s official report gives the impression of a unanimous rejection of the suspected harms. However, the EMA’s internal report (…) tells a very different story. This “internal report is confidential but has been leaked,” the group notes, and it “reveals that several experts had the opinion that the vaccine might not be safe and called for further research, but there was nothing about this in the official report.”
  • “The EMA asked the pharmaceutical companies to search for side effects of the vaccine in their own databases and did not check the companies’ work for accuracy,” they say. They also allege that their criteria to consider cases as POTS were extremely restrictive: “In the search for cases coded as POTS (…)  almost half (40 cases) are dismissed for not meeting the case definition for POTS”.  “This is extraordinary, as the companies have a huge vested interest in not finding these possible harms in their databases,” the Nordic group comments.
  • Another issue is the placebo that was used in the clinical trials of HPV vaccines. “In all the vaccine trials apart from a small one, the control group was given a placebo that contained an aluminium adjuvant, which is suspected of being neurotoxic,” they note. The group quotes information contained in the leaked internal documents: “Initially, the vaccine was compared with a placebo group being vaccinated with physiological serum, whereby the number of adverse reactions was much higher and much more serious than in the control group. After comparing 320 patients in the saline placebo group, a quick move was made to an aluminium-containing placebo, in order to be able to only evaluate the effects of the active substance. However, this distorted the comparison (…)”. “We believe this constitutes scientific misconduct,” the Nordic group says.
  • The group highlights the “extreme levels of secrecy” that surround the EMA review process, in which experts who are involved in the process are not named and are bound by lifelong secrecy about what was discussed. Nordic Cochrane argues that instead, all documents involving HPV vaccination safety should be made publicly available.
  • They also question whether EMA has behaved fairly, in particular towards Dr. Louise Brinth, the Danish whistle-blower who first described cases of POTS in the medical literature, as EMA accuses her to report on “a sample of patients, apparently chosen to fit a pre-specified hypothesis of vaccine-induced injury”. The Nordic group concludes “We find that the EMA’s comments are unprofessional, misleading, inappropriate and pejorative, and that the EMA’s approach (…) is unscientific”.

Dr Brinth, who cosigns the Nordic Cochrane complaint, has published her own 63-page response to the EMA review (it’s really worth a read).

The situation in Japan

Japan puts in place a scheme to manage symptoms after HPV vaccination

HPV vaccine 2 japanese girls

Japan has put in place a scheme to manage symptoms, especially generalized chronic pain, that have arisen after HPV vaccination. Guidelines for the evaluation and management of symptoms that begin after HPV vaccine injection were issued to healthcare professionals and approved by the Japan Medical Association and the Japanese Association of Medical Sciences.

Class action lawsuit filed against Japanese government and vaccine manufacturers

Sixty-three women and girls who reported side effects from cervical cancer vaccines sued the Japanese government and drugmakers. “More plaintiffs are expected to join the suit “, The Japan Times recently reported.  According to the Japanese Ministry of Health, Labor and Welfare, 2,945 of the 3.39 million women who had received the vaccines, or 0.09 percent, have reported side effects.

Scientist accuses WHO, GAVCS, CDC of misconduct

In an open letter of complaint to the World Health Organization (WHO), Japanese Dr. Sin Hang Lee expresses concerns regarding the conduct of certain members of GACVS, WHO, CDC and other scientific/health professionals. “I have come into possession of documentation which leads me to believe multiple individuals and organizations deliberately set out to mislead Japanese authorities regarding the safety of the human papillomavirus (HPV) vaccines, Gardasil and Cervarix”, he writes.  In his letter he explains that there is at least one known mechanism of action explaining why serious adverse reactions occur more often in people injected with HPV vaccines than other vaccines, and why certain predisposed individuals may suffer a sudden unexplained death as a result, but he alleges that this information was deliberately “ignored” by the experts.


Potential risk of Primary Ovarian Failure associated with HPV vaccination

HPV vaccine 2 American-College-of-PediatriciansThe American College of Pediatricians (ACP) issued a statement in January 2016 warning of a potential relationship between Primary Ovarian Failure and HPV vaccination.

“It has recently come to the attention of the College that one of the recommended vaccines could possibly be associated with the very rare but serious condition of premature ovarian failure (POF), also known as premature menopause“, they report.

They further state that, although most physicians are probably unaware of a possible association between the HPV vaccine  and POF, and may not consider reporting cases or prolonged amenorrhea (missing menstrual periods) to the Vaccine Adverse Event Reporting System (VAERS), 213 cases were reported. When the cases are more carefully chosen:  “86/89 cases are associated with Gardasil, 3/89 with Cervarix, and 0/89 with other vaccines administered independently of an HPV vaccine. Using the same criteria, there are only 7 reports of amenorrhea from 1990 through 2005″.

“While there is no strong evidence of a causal relationship between HPV4 and ovarian dysfunction, this information should be public knowledge for physicians and patients considering these vaccines”, they conclude.

A possible association between ovarian problems and the HPV vaccine had been already reported by Dr Deirdre Little, an Australian gynecologist:

It should be mentioned that the ACP statement, as well as Dr. Little’s research have been heavily criticized by other physicians.



HPV vaccine 2 Should I get HPV Vaccine

I was hoping that, with the new available information on the HPV vaccine safety, I could reach a conclusion on how to counsel, as a physician, young women and mothers asking me whether to get the HPV vaccine or not. I was expecting to have a thorough review stating loud and clear the HPV vaccine expected benefits vs. the documented risks.  Unfortunately, no conclusion can be easily drawn so far. It is extremely difficult to find a balance between the scientific evidence -with studies not always well-designed-, the experts’ opinions and the increasing criticism surrounding this vaccine.

While most professional societies urge us to promote vaccination, the constant reports on serious side effects coming from all around the globe cannot be ignored. It’s unfortunate to see a woman dying of a cancer that could have been prevented, but it is equally heart-breaking to see a healthy teenager, full of life, suddenly prostrated in a wheelchair…

I have no doubt that vaccines are an invaluable public health tool against fatal diseases, and it’s imperative that we all continue to believe in vaccines. However, it’s my opinion that the HPV vaccine in particular deserves further study.

The unanswered questions are too many, not only about potential risks, but also about potential benefits. Therefore, I believe that further independent research is urgently warranted – not just in Denmark, but worldwide. With  more than 175 millions vaccine doses distributed in 63 countries, it is certain that a coordinated, global effort would shed light on some aspects of this controversial vaccine.


I am genuinely grateful to Ms Caron Ryalls, who kindly contacted me and provided me with some of the information presented here.