As we approach the release of the Covid-19 vaccine, people want to know how well the vaccines have been developed and the groups of people in which they have been tested.
There has been some debate in Ireland in recent days about whether vaccines from Moderna, Pfizer and AstraZeneca, for example, have been tested in older groups.
Speaking on Claire Byrne Live RTÉ on Monday 30 November, Professor Sam McConkie said most of the people taking part in the vaccine were between the ages of 18 and 55.
McConkie, an infectious disease specialist at the Royal College of Surgeons of Ireland (RCSI), said that “if we had a vaccine that would be 100% effective in preventing death in the elderly, people over 80, over 90 and the vulnerable, which would be really good ”.
“Unfortunately, in most Phase 3 studies, most of the people in it are young, healthy people between the ages of 18 and 55, so these vaccines may work really well to prevent mild to moderate diseases in young, healthy people between the ages of 18 and 55. to 55, but we know it’s not really the group that really suffers from Covid-19 death or serious illness, ”McConkie said.
Several vaccines have now gone through three main phases of clinical trials and are trying to distribute them worldwide. Several factors are being studied during clinical trials, including:
- how well the vaccine protects against infection
- best dose
- any side effects
Let’s look at the three leading vaccines from Moderna, Pfizer and AstraZeneca and the extent to which their clinical trials included people from older age groups.
The advanced vaccine, mRNA-1273, began its Phase 3 clinical trial in July, involving 30,000 adult study sites in the United States.
The first results of a clinical study revealed that the vaccine, which Moderna hopes will be ready to ship 20 million doses to the United States by the end of 2020, was 94.5% effective.
The vaccine uses messenger RNA (mRNA), which means that the immune system is not exposed to the actual virus itself, but it still causes antibodies to form in the immune system.
Moderna is currently submitting a vaccine authorization to the US Food and Drug Administration (FDA) and the European Medicines Agency (EMA).
Eligibility requirements in the trial included the need for participants to be at least 18 years of age and not to have previously participated in a Covid-19 vaccine or treatment study.
Applicants were required to be healthy without a previous history of Covid-19, and if they already had any medical conditions, their conditions should be stable at the time of screening.
The study looked at participants who were at high risk for Covid-19 infection because of their location or conditions, or who were at high risk for Covid-19 because they were over 65 or had an underlying disease.
Source: Moderna / YouTube
Phase 3 of a modern clinical trial involved more than 7,000 people over the age of 65. Among the participants in the Phase 3 trial of the Modern vaccine:
- 29% were between 25 and 44 years old
- 39% were between 45 and 64 years old
- and 25% were older than 65 years.
By comparison, 9.3% of the world’s population is over the age of 65, according to the United Nations Department of Economic and Social Affairs.
This varies from region to region: 18.4% of the population is over 65 in high-income countries, 8.2% in middle-income countries and 3.3% in low-income countries.
Pfizer and BioNTech
The UK has officially approved a vaccine developed by Pfizer and BioNTech that has been approved for emergency use by the UK Medicines and Healthcare Products Regulatory Authority (MHRA).
Pfizer has been shown in clinical trials to be 95% effective and free of serious side effects and has passed safety tests.
Pfizer and BioNTech have said they plan to produce up to 50 million vaccines worldwide in 2020 and up to 1.3 billion in 2021.
The UK Department of Health and Welfare said in a statement that after months of “rigorous” clinical trials and data analysis, the MHRA “concluded that the vaccine met stringent safety, quality and efficacy standards”.
“The Joint Vaccination and Immunization Committee (JCVI) will soon publish final recommendations for vaccine priority groups, including nursing home residents, health and care workers, the elderly, and the clinically extremely vulnerable,” the department said.
The vaccine is expected to be available in the UK from next week.
A recent vaccine clinical trial involved 43,931 participants, 42,722 of whom received the second of the two vaccines.
The vaccine has been studied in 150 clinical trials in the United States, Germany, Turkey, South Africa, Brazil and Argentina. On all international sites, 41% of participants are between the ages of 56 and 85.
In the US, 45% of participants are in the same age group.
The effectiveness of the vaccine was “consistent with age, gender, race and ethnicity demographics”.
The study looked at more than 94% effectiveness in adults over 65 years of age.
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The AstraZeneca vaccine, developed at the University of Oxford, has been clinically tested in two different dosing regimens.
The first regimen tested, which included a first dose in half and a standard second dose, was found to be 90% effective.
For the second dosing regimen, which consisted of two full doses, the efficacy was 62%.
In the second phase of the study on the safety and immunogenicity (ability to cause an immune response) of the vaccine, 560 participants:
- 160 were between 18 and 55 years old
- 160 were between 56 and 69 years old
- and 240 were 70 years of age or older.
Vaccine adverse reactions decreased with age, and fewer adverse events were observed in the elderly than in those aged 18 to 55 years.
The study found that the antibody responses in the two older age groups were “comparable to those seen in younger adults”.
“Similarly, antibody levels increased after the second dose of the vaccine, and this was consistent in the elderly.”
The study notes that “further evaluation of the effectiveness of this vaccine is needed in all age groups and people with co-morbidities” and that more attention should be paid to those living in care or over 80 years of age.
“Larger studies are now underway to evaluate immunogenicity, safety and efficacy in older adults with a wider range of co-morbidities.”
In recent vaccine clinical trials involving 24,000 participants from the UK, Brazil and South Africa, the University of Oxford has stated that interim phase III data “based on comparative reviews of Oxford Phase I / II studies have shown that the vaccine induces strong antibodies and T cellular immune responses in all age groups, including older adults, and has a good safety profile ”.
In essence, Covid-19 vaccines, such as those from Moderna, Pfizer and AstraZeneca, have been tested in the elderly, and there has been a significant proportion of older people in clinical trials with each vaccine.
For two shared data, Pfizer and AstraZeneca, the efficacy of vaccines in the elderly has been more consistent with the results. Current vaccine research is ongoing.
The next phase of the clinical trial – the fourth phase – will involve tracking participants in the coming years.
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Applicants had to be healthy without a history of Covid-19 and, if they already had medical conditions, their conditions had to be stable