Tuesday , September 28 2021

Have Covid-19 vaccines been tested in older age groups?

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As we get closer to the release of the Covid-19 vaccine, people want to know how well-engineered vaccines work and on what groups of people they have been tested.

In Ireland, there has been discussion in recent days about whether vaccines such as those from Moderna, Pfizer and AstraZeneca have been tested on groups of older people.

Speaking at Claire Byrne Live at RTÉ on Monday, November 30, Professor Sam McConkey said most of the people who take part in vaccine trials are between the ages of 18 and 55.

McConkey, an infectious disease specialist at the Royal College of Surgeons Ireland (RCSI), said that “if we had a vaccine that was 100% effective in preventing death in the elderly, those over 80 and 90, and those at risk, and also to prevent the transfer to other people who were widely available at the time, that would be really good ”.

“Unfortunately, in most Phase 3 trials, most of the people who sign up for them are young, healthy people between the ages of 18 and 55, so it’s likely that these vaccines work really well at preventing mild to moderate disease in young, healthy people aged 18 to 55.” 18 to 55, but we know this is not really a group that is really suffering from death or severe illness from Covid-19, ”said McConkey.

Several vaccines have now passed through three key phases of clinical trials and are expected to be distributed worldwide. A number of factors are investigated during clinical trials, including:

  • how well the vaccine protects against infection
  • best dose
  • any side effects

Let’s look at the top three vaccines from Moderna, Pfizer and AstraZeneca, and to what extent their clinical trials have included people in older age groups.


The Moderna vaccine, mRNA-1273, began Phase III clinical trials in July in 30,000 adults at research centers in the United States.

Early results from clinical trials showed that the vaccine, which Moderna hopes to have 20 million doses ready for shipment by the end of 2020 in the US, proved to be 94.5% effective.

The vaccine uses messenger RNA (mRNA), which means that the immune system is not exposed to the virus itself, but still triggers the production of antibodies in the immune system.

Moderna is currently applying for vaccine approval to the US Food and Drug Administration (FDA) and the European Medicines Agency (EMA).

The entry requirements for the study were that participants must be 18 years of age or older and have not previously participated in the Covid-19 study or treatment study.

Applicants had to be healthy with no prior history of Covid-19, and if they had any pre-existing medical conditions their condition had to be stable at the time of screening.

The study looked for participants who were at high risk of becoming infected with Covid-19 because of their location or circumstances, or who were at risk of developing severe Covid-19 because of their age over 65 or the underlying disease.

Moderna's qualification requirements

Source: Modern

Source: Moderna / YouTube

More than 7,000 people over the age of 65 were participants in the phase 3 clinical trial of Moderna. Moderna vaccine phase 3 trial participants:

  • 29% are between the ages of 25 and 44
  • 39% are people aged 45 to 64
  • and 25% were over the age of 65.

For comparison, according to the United Nations Department of Economic and Social Affairs, 9.3% of the world’s population is over 65 years old.

This varies by region – in high-income countries, 18.4% of the population is over 65, 8.2% in middle-income countries, and 3.3% in low-income countries.

Pfizer and BioNTech

The UK has formally approved a vaccine developed by Pfizer and BioNTech that has been approved by the UK’s Medicines and Healthcare Products Regulatory Authority (MHRA) for emergency use.

In clinical trials, the Pfizer vaccine has been shown to be 95% effective without serious side effects and has passed safety tests.

Pfizer and BioNTech 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 Human Services said in a statement that after months of “rigorous” clinical trials and data analysis, the MHRA “concluded that the vaccine meets strict safety, quality and efficacy standards.”

“The Joint Immunization and Immunization Committee (JCVI) will shortly publish its final recommendations for priority groups that will receive the vaccine, including nursing home residents, healthcare and healthcare professionals, the elderly and clinically vulnerable people,” the unit said.

The vaccine is expected to be available in the UK from next week.

A recent clinical trial with the vaccine enrolled 43,931 participants, 42,722 of whom received the second of the two vaccines.

The vaccine has been studied in 150 clinical trial sites in the USA, Germany, Turkey, South Africa, Brazil and Argentina. Across all sites at the international level, 41% of participants are between the ages of 56 and 85.

In the United States, 45% of participants are in the same age range.

Vaccine efficacy was “consistent across age, gender, race and ethnicity.”

The study showed an effectiveness of over 94% in adults over 65 years of age.

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AstraZeneca (Oxford)

AstraZeneca, developed at the University of Oxford, has been clinically tested on two different dosing schedules.

The first regimen tested, which comprised the halved first dose and the standard second dose, was found to be 90% effective.

The second dosing schedule, which administered two full doses, was 62% effective.

In a Phase II safety and immunogenicity (ability to produce an immune response) study of the vaccine in which 560 participants were involved:

  • 160 were between the ages of 18 and 55
  • 160 were between the ages of 56 and 69
  • and 240 were 70 years of age or older.

Adverse reactions to the vaccine decreased with age, with fewer adverse events reported in the older age groups than in those 18 to 55 years of age.

The study found that the antibody responses in the two older age groups “were comparable to those seen in younger adults”.

“Similarly, after the second dose of the vaccine, the antibody levels increased, which was also consistent with the older age groups.”

The study noted that “further evaluation of the effectiveness of this vaccine is warranted in all age groups and people with comorbidities” and that special attention should be paid to those living in nursing homes or over 80 years of age.

“Larger studies are now underway to assess immunogenicity, safety, and efficacy in older adults with a wider range of comorbidities.”

In a recent vaccine clinical trial involving 24,000 participants from the UK, Brazil and South Africa, the University of Oxford said the provisional Phase III data “are based on peer-reviewed results from Oxford I / II studies. showed that the vaccine elicits a strong immune response to antibodies and T cells in all age groups, including the elderly, and has a good safety profile. ‘

Basically, Covid-19 vaccines, such as those from Moderna, Pfizer, and AstraZeneca, have been tested in older age groups, with older adults making up significant proportions in clinical trials of each vaccine.

Two for which data were made available – Pfizer and AstraZeneca – vaccine effectiveness among older adults is in line with the results on a larger scale. Vaccine research is ongoing.

The next phase of clinical trials – phase four – will include monitoring with participants in the coming years.

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applicants had to be healthy with no prior history of Covid-19 and if they had pre-existing medical conditions their condition had to be stable

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