A vaccine against COVID-19 may not be as effective in older people who are most at risk of suffering complications and dying from the disease, according to U.K. researchers.
However, some experts say immunizing those around the elderly may help protect them.
Speaking at the House of Lords science and technology committee in London, U.K., researchers said targeting different groups in the population with vaccines should be closer studied as the world races to develop a vaccine for the novel coronavirus.
“Sometimes it is possible to protect a vulnerable group by targeting another group and this, for example, is being done with influenza. In the past few years, the U.K. has been at the forefront of rolling out the live attenuated vaccine for children,” Prof. Peter Openshaw from Imperial College London said at the committee hearing earlier this week.
Openshaw said administering the seasonal nasal spray flu vaccine to children who do not often get severe influenza helps protect their grandparents, for example.
The same could be said for COVID-19 vaccine, he added.
Dr. Eleanor Fish, an immunology professor at the University of Toronto, told CTVNews.ca that a coronavirus vaccine may not work on the elderly because their immune systems are “not as robust” as those of younger people.
“If you are immunocompromised or if there is any way your immune system is weaker than it should be, then your body might not have the ability to adequately respond to the vaccine,” Fish explained in a telephone interview on Wednesday.
When considering the seasonal flu shot, Fish said the elderly are typically given a larger dose of the flu vaccine so their immune systems have a better chance of recognizing and responding to the vaccine.
However, she warns that there are still a lot of unknowns in regards to a COVID-19 vaccine.
“We don’t know that if any of the vaccines being developed are going to be effective. We don’t know whether… the key antibodies and the neutralizing antibodies are going to be effective against the virus,” Fish said
“But if we assume that there is going to be an effective vaccine [for] healthy adults and presume that healthy adults take the vaccine, there is still the potential that the vaccine my not prompt a response in the elderly.”
While some of the coronavirus vaccine candidates are showing promising results, U.K. scientists said more research needs to be done to understand what goes wrong with the immune system as people get older that makes them more susceptible to communicable diseases.
Arne Akbar, professor of immunology at University College London and president of the British Society of Immunology, said at the hearing that a better understand of an aging immune system is not just important for COVID-19, but for other diseases as well.
“One thing that’s apparent, even in healthy older people, is that there’s more inflammation all around the body. We need to understand where that inflammation is coming from,” Akbar said. “And this baseline inflammation in older people is linked to frailty and many negative outcomes as we get older. And this seems to be exacerbated when you get a severe infection like COVID-19.”
“But what is the source of the inflammation in the first place? That’s something that we really need to get to grips with,” he added.
Fish said in order for a COVID-19 vaccine to work in older people, they may need a higher dosage of the vaccine, require additional booster shots every couple months or have to use it in combination with another treatment.
It is unclear who will be the first to get the vaccines, but the ones most at risk of getting infected would likely be inoculated first, according to Kerry Bowman, a clinical ethicist at the University of Toronto.
Bowman said Wednesday that health-care workers, other first responders, and the elderly could be among the first.
However, given that older people’s immune systems are weaker, Bowman said it may be more effective to vaccinate everyone who may come into contact with the elderly.
“What can be done is to immediately create a protective zone around older people… Make sure that people working in long-term care facilities are immediately vaccinated so that you’re protecting those older people. And then families that have older people that they’re caring for or visiting regularly,” Bowman said in a phone interview with CTVNews.ca.
While this could help protect the elderly, Fish said it will only be successful if the vaccine is effective.
“We have to be confident that we have a vaccine that’s 100 per cent effective so you can build that wall of immunity,” Fish said. “Until we know what’s going on with the vaccine and how effective it is, we don’t know for sure how it will impact the elderly.”
Bowman said of those vaccines that are moving towards human trials, none are using older people in their research because of the potential risks.
When Canada gets a vaccine, Bowman said the demand will be high and there will be ethical questions about who will get it first.
“If we get a vaccine, it’ll be helpful but it may not be helpful for some of the most vulnerable people,” Bowman said.
It is not yet known what level of immune response will be required to protect humans against COVID-19, but Fish said developing vaccines to fight the virus is still important.
“Imagine if we have one or two vaccines in the next 6 months? That will change the face of COVID-19 regardless of who takes it,” Fish said.