A small but growing body of research suggests that the highly contagious delta variant increases your risk of serious illness, but it’s hard to know if this is the root cause of more severe COVID-19, say researchers and outside experts.
Latest results from Singapore, Published this week in the peer-reviewed medical journal Clinical Infectious Diseases, which includes a comparison of 829 hospitalized patients with one of three variables of concern – including delta – and 846 patients admitted to hospitals with the original coronavirus strain in early 2020.
“After adjusting to age and gender, [delta] It was associated with higher odds of needing oxygen, admission to the intensive care unit, or death.”
“The results of the study are similar to those seen in an extensive analysis of nationwide data in Singapore and a detailed study of patients with severe outcomes,” the paper said.
The conclusions also echo other international studies, including one from scotland And The last of the team in Ontario, and both found an increased risk of severe outcomes after delta variant infection.
“There appears to be a trend towards more oxygen and more intensive care units among individuals with delta than in previous variants,” said Dr. Zane Chagla, an infectious disease specialist at McMaster University in Hamilton, Ontario, who is aware of it. Three papers.
But while all of these studies link delta to cases of severe disease, determining whether the same variant causes more severe disease—and what mechanism works, if so—is difficult to confirm in real-world research.
Measuring the intensity presents a challenge to researchers
The difficulty stems from the fact that researchers cannot easily conduct a controlled human trial – exposing patients to delta and the original coronavirus – for ethical and practical reasons. Instead, they have to rely on data collected after the event, and compare groups that might differ in other ways.
The research team in Singapore acknowledged that “it is uncertain to what extent this association reflects the effect of a variable, an opportunity detection due to relatively small sample sizes, or differences in groups of individuals not considered in the multivariate models.” in their paper.
Angela Rasmussen, a virologist with the University of Saskatchewan’s Vaccines and Infectious Diseases organization, said the study’s limitations speak to the fact that measuring the severity of a variant between individuals is quite challenging — and even more challenging when you’re trying to compare infections between one. group with another at a different time.
She said that even people in the same community have different sleep patterns, health issues and diets, making it difficult to analyze why some people get sick, and others don’t, at the individual level.
It’s also hard to know, Rasmussen said, if someone is seriously ill because of the delta itself, or whether they’ll get a similar result from another, less contagious type of virus.
“What would happen if we could reverse that? Would the results be the same? Would this person really get sick anyway?” I wondered.
While more research is needed, Dr. Abrar Karan, an infectious disease fellow in Stanford University’s Division of Infectious Diseases and Geographical Medicine, said any indications that Delta may cause more serious infections is worrisome, given the number of people who haven’t They are vaccinated and are susceptible to infection with this virus. .
The older population remains at high risk, but Karan said he is also concerned about younger adults who typically have some of the lowest vaccination rates despite being eligible for their vaccinations.
“I am concerned that these people will pass it on to the elderly, or to people who are immunocompromised,” he said. “I am concerned about some of these young people who have some comorbidities such as obesity.”
Concern added that many adults who are not immunized may now face a higher risk of serious outcomes even if they do not have other pre-existing health problems.
“People end up being more in the hospital, needing more oxygen, requiring more ventilation — at a younger age,” he said.
Watch | Delta may continue to hit younger age groups, the doctor warns:
Deltas are associated with higher viral loads
While the exact risk of seriousness from delta may still be murky, what is most evident is the variant’s ability to spread among people and eventually infect those at risk of the worst outcomes – which may explain the higher rates of hospitalization, including higher rates of childhood illness. dangerous, in some US states with low vaccination rates.
“If you have a large group that is not immunized, you will see an outbreak, and you will see severe disease as well,” Karan said.
Many experts also agree that “breakthrough” infections after vaccination will continue to occur as deltas are widespread – now making up the bulk of Canada’s cases – but it is important to note that contracting this virus is not the same as getting seriously ill from who-is.
Other research has also hinted at why deltas spread so quickly among people, where high viral loads likely play a role.
How much height is not entirely clear, with Studies indicate Deltas can mean 300 to 1,000 times more virus inside a person’s body, and it’s also hard to know how these viral loads relate to disease severity.
This is a “chicken and egg” question, Rasmussen said: Do you really get sick because the virus reproduces at such high levels? Or is it multiplying at such high levels because your body’s immune response is inadequate and you are really sick?
“It doesn’t really matter why deltas are more transmissible, or they can cause more sudden injuries – it can,” she added. This is what we should pay more attention to.”
Watch | Experts say vaccination is key to avoiding the worst of the delta variant:
Vaccines remain effective in reducing risks
Amid all the questions and doubts, the reassuring constant is that vaccination can still provide great protection against the worst outcomes of the coronavirus even if you are delta infected.
“Vaccination status was associated with lower risk,” the Singapore research team wrote.
Previous Scottish research also indicated that Oxford-AstraZeneca and Pfizer-BioNTech shots were “effective in reducing the risk of SARS-CoV-2 infection and COVID-19 hospitalization” associated with the delta variant.
Karan stressed that while everyone should maintain some personal precautions to ward off Delta, such as wearing a mask in public, regardless of their vaccination status – there is a different risk profile for each group.
“Should you worry about sending Delta to the hospital, or you getting really sick, or your family getting seriously ill?” He said.
Karan quickly answered his question: For healthy, fully vaccinated people, this is still not usually the case.