As Albertans largely stay home to follow public health orders and recommendations related to the COVID-19 pandemic, some people are musing over whether different approaches to the health crisis should be considered in an effort to build up herd immunity.
While holding a news conference Wednesday to offer Albertans a look at provincial modelling so far with respect to COVID-19, Premier Jason Kenney acknowledged that some have questions about whether the province could employ a different approach.
“I’ve seen online and some of the chatter and discussions here, people saying, ‘Well why don’t you just kind of close down the seniors’ homes and quarantine the seniors and let the rest of society continue to function?'”
“Well… no age group is immune… We have had two deaths, I think one amongst a 20-something and one amongst a 30-something, so young people can be seriously affected by this.”
A recent article in the MIT Technology Review explains herd immunity as a concept that applies to a virus spreading until so many people have been infected that the outbreak begins to recede because people build up immunity and the virus finds it more difficult to find a susceptible host.
Dr. Deena Hinshaw, Alberta’s chief medical officer of health, tweeted on April 5 that she has also heard questions about whether to let COVID-19 spread among young and healthy groups to increase the population’s immunity to the novel coronavirus that causes COVID-19.
“We don’t know who will have a severe case of COVID-19,” she tweeted. “Some who are young and healthy will have severe illness and even die.
“Until we know more about who may be at greatest risk and more evidence about treatments, the best way to prevent severe illness is for all of us to perform physical distancing, stay home when possible and avoid non-essential activities.”
Two infectious disease specialists, both based in Alberta, agree and tell Global News unequivocally that allowing COVID-19 to spread among young people with the aim of building up herd immunity is simply a bad idea.
“It is true that infection can range from being almost unnoticeable through deathly, however, a significant proportion of COVID-19 cases who are critically ill and die are young people,” says Dr.Lynora Saxinger, a physician specializing in infectious diseases at the University of Alberta.
“I see no benefit to this, because if we can control the disease in the population through carefully staged public health measures, hopefully we can get through to an effective vaccine with fewer deaths overall.”
Watch below: A video about herd immunity.
Saxinger adds that if a large number of young people get sick in a short period period of time and health-care resources are unable to cope, there is a higher risk of death from COVID-19, not to mention other diseases since “unchecked transmission increases deaths of all causes” because there aren’t enough resources to care for medical episodes like heart attacks, given that people could spend weeks on ventilators.
Dr. Craig Jenne, an infectious disease specialist at the University of Calgary, agrees.
“We do know that severe disease and mortality is lower in younger people, however, they do still get sick, they do still end up in the hospital and they do still end up dying,” he says. “Currently there is no way of predicting who will have minor symptoms and who will have severe disease or death.
“Even if this strategy worked, only this population of people would have herd immunity — this is not a transferrable protection. That is, the older people who are not exposed to the virus would have not protection.”
Jenne noted that herd immunity differs for each virus.
“With influenza, we typically approach this level of protection through a combination of natural exposure with recovery along with vaccination. Currently we do not have a vaccine option for COVID-19 and overall mortality rates are much higher than influenza, meaning more people will die from COVID-19 than from the flu during natural exposure and recovery. This is not a good approach to dealing with the current situation.”
Saxinger also says it’s too early to know what will be enough to achieve herd immunity when it comes to COVID-19.
“It will be challenging to try to keep people’s livelihoods safe, and the restrictions are a strain for sure, but you can’t even worry about a livelihood if you don’t have a life.”
Jenne also explains there are ethical components to discussing herd immunity when it comes to COVID-19.
“I am not sure if there is a ratio that would justify a disease management strategy that intentionally involves exposing healthy individuals to a virus that may kill them, leading to otherwise preventable deaths,” he says.
“By easing social distancing, you would essentially be ensuring higher levels of transmission not only within the younger cohort of patients, but also to other family members, household members and community members.
“Though the idea of herd immunity through natural exposure may seem appealing, it is nearly impossible to keep it within one group of patients.”
How will the successful development of a vaccine impact herd immunity and the COVID-19 pandemic?
“Vaccines will be a critical component of an eventual herd immunity,” Jenne says. “Basically, an effective vaccine will offer a patient the same level of protection as being exposed to, and recovering from the virus.
“The advantage here is that vaccination comes with minimal health risk to the patient. As most vaccines do not contain live virus, there is no risk of infection in at-risk patients, and once a sufficient number of the population have either recovered from the infection or have been vaccinated, herd immunity will be achieved.”
Jenne adds that even vaccines that are less than optimal are still likely to reduce the severity of illness and reduce mortality.
Saxinger says there are currently a number of promising developments on the vaccine front.
Saxinger used a fire analogy to explain how the successful development of a vaccine could be a game-changer.
“Imagine you have a fire that is spreading across a dirt field — jumping from dry twig to dry twig — with the twigs representing susceptible people. Now remove the twigs.”
Is there solid evidence to suggest someone who has COVID-19 can’t get infected again?
Both Saxinger and Jenne say there is evidence to suggest people who become sick with COVID-19 will not be reinfected.
Jenne says evidence, including blood samples screened for immune molecules, from people who have recovered from COVID-19 “indicates these individuals now have protective immunity.”
“Principally, we are looking for an immune molecule know as antibodies,” he says. “These are highly specific proteins that can bind to the virus. Essentially, getting the body to make good antibodies is the goal of most vaccines.
“In the recovered COVID-19 patients, the antibodies that are generated both recognize the virus and neutralize the virus, preventing it from entering our cells and helping the body clear the infectious particles.”
He says the amounts to “very strong evidence that people who have recovered are now protected.”
Saxinger says that even though she’s seen a couple of media reports of suspected reinfection, “they never confirmed that the virus itself could be isolated again, and there’s a fairly strong possibility that the PCR (polymerase chain reaction) test — which is very sensitive — was positive and negative then positive again as the amount of viral remnants declined in the swabs as the person improved.”
“The reason for that could be changes in how the sample was collected, or related to the fact that no test is perfectly sensitive,” she says. “There have also been some animal studies in macaques showing that after infection, you could not reinfect the animal and that you can still recover these viral remnants by PCR for a period of time after infection.
“Studies in a small number of people showed that the active virus seems to clear in the over first week or so of symptoms and then the immune system’s antibody response, which seems to be protective and neutralize the virus, occurs over the next two weeks. During that time, the PCR test can remain positive.
“So the indications are that it is unlikely that people can be reinfected and that people would be expected to be immune after infection, although, whether everyone becomes immune and the duration of the immunity is not yet determined.”
Jenne says the SARS coronavirus outbreak in 2002 and 2003 also sheds light on the ambiguity that remains over whether people who become infected can know with absolute certainty they will not be reinfected.
“It is too early to determine this for COVID-19, but the data from SARS suggests at least two years.”
Watch below: Some Global News videos about SARS.
How much of a concern is virus mutation in the COVID-19 context?
“So far, these small these changes don’t appear to alter the areas of the virus that interact most strongly with the immune system. Those are the areas that will be targeted for a vaccine, so it looks promising that these small changes will not affect the ability of a vaccine to protect against many strains.”
Jenne also says “emerging evidence suggests there are multiple viral variants in the community already.”
“This often poses a bit of a problem for vaccines and actually explains why we need a new flu shot ever season. Coronavirus seems to mutate more slowly than flu, so mutation may be of a lesser concern with COVID-19,” he says.
Jenne notes that people who are naturally exposed to the novel coronavirus and have recovered “develop an immune response that recognizes many different parts of the virus.”
“Because of this, the virus would have to mutate all of these entities to escape the immune response,” he says. “So, a slow mutation rate in coronavirus is unlikely to impact herd immunity to any great extent.
Like Saxinger, however, Jenne acknowledges the story may be different for vaccines.
“For this reason, our best vaccines use multiple parts of the virus to ensure that one or two mutations does not allow the virus to escape,” he says. “Many of the vaccines in clinical trial for COVID-19 take this approach, providing multiple targets, helping to ensure any herd immunity generated by vaccination should be able to withstand some viral mutation.”
Alberta’s COVID-19 approach continues to revolve around social distancing and reducing spread
On Wednesday, as Kenney spoke about provincial COVID-19 modelling and addressed the suggestion by some that Alberta should let COVID-19 spread among young and healthy people, he reiterated the government’s commitment to its current approach to the public health crisis.
He acknowledged Alberta has “the youngest population in Canada” and noted that “counts for a lot in a disease like this which attacks the elderly much more aggressively.”
“It also underscores why we do need to put in place special measures that focus on our elderly population, and that is reflected for example in Dr. Hinshaw’s latest prioritization of access to testing, which now includes making that available to people who generally are over 65 who are symptomatic.”
Kenney also noted Wednesday that a disproportionate number of people infected are younger.
“They are young or middle-aged, but of course, a disproportionate number of those who have passed away, 25 per cent, of those in the 80-plus age category who have been confirmed positive with COVID-19 have unfortunately passed away,” he said.
“This underscores a couple of things. The fact that most people who end up with the virus are younger, their symptoms may not manifest, they may not know it, but they all need to play a role in limiting the spread.”
On Friday, Hinshaw spoke at a news conference in Edmonton and announced the province has recorded seven additional deaths from COVID-19, bringing the total to 39 since the pandemic hit the province.
She also said there were 49 new cases in the province, bringing the total to 1,500 and that 713 people have now recovered from COVID-19.
Watch below: Some Global News videos about Alberta’s response to COVID-19.
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