Randall Enos, CagleCartoons.com

Randall Enos, CagleCartoons.com

Commentary: Know your risk: what the science says about COVID-19 spread

By Chris Janetopoulos

The Baltimore Sun

There is much confusion regarding COVID-19 spread — understandable given the evolving nature of the data set and the proliferation of misinformation. Before children head back to school, it’s critical their teachers and parents understand the risks.

It has been demonstrated that all ages can be infected by the virus, and the older you are, the more likely you are to have complications. While rare, very serious illness and death can occur in children, and preconditions in children and adults can contribute to hospitalization. Multiple studies have come in the past month demonstrating school attendance does not appear to play a strong role in COVID-19 spread and that opening schools has had little direct effect on community transmission.

National Geographic was recently given exclusive access to an Icelandic study that provides some clarity on transmission between individuals. Scientists from the Directorate of Health and deCODE genetics out of Reykjavik monitored every citizen in the country after being potentially exposed to COVID-19 during spring 2020. Children were defined as under age 15 and found to be half as likely to be infected; they were additionally half as likely as adults to transmit the virus. Interestingly, almost all of the COVID-19 transmissions to children came from adults.

Other data has suggested underlying mechanisms that may account for these findings. While the ACE2 receptor has been implicated in infection and appears to be downregulated in most children, an additional study out of Vanderbilt University found that an enzyme that helps chop up the spike protein increases in expression in adults. This processing is thought to assist viral entry into the cell, and its presence in certain cells of the lungs correlated with COVID-19 infection. In addition to having a strong innate immunity and more diverse antibody repertoire that protects against COVID-19 infection, children may also be protected because they lack proteins needed for infection of certain cells in the lungs.

As the data continues to accumulate, a picture is starting to emerge that makes scientific sense regarding the differences in infectivity and disease we are seeing across age groups. When children do get infected, the majority quickly eliminate the virus. Therefore, the time that they are infectious is shortened, providing less duration for them to infect their cohorts, and potentially limiting their symptoms. Given it may take a larger dose of virus to become infected if you are a pre-adolescent child, overall transmission between children should be lower.

On the other hand, adults have a weaker innate immunity, and they also have the proper proteins expressed in their lungs permitting infection, so it may take a smaller viral load for an adult to get infected from a child. Conversely, adults, because they are poor at clearing the virus, are infectious longer, may have higher viral loads, and would typically develop worse symptoms. Adults also have a larger lung capacity and would expel air for further distances, which would have a greater likelihood of infecting everyone. Additionally, the older you are, the more likely you are to have dysregulated immune function and preexisting conditions. Taken together, numerous properties of the virus, your immune response and your physiology work together to determine the probabilities of infectivity and disease.

This model suggests that teachers and staff, and adults in general, should be cautious around children, but even more so with other unmasked adults, including colleagues at breaks and lunches. Lastly, it is important that researchers carefully determine the degree to which children, or subsets of children with preconditions, infect one another, as it has implications for who should have priority for vaccinations.

Interestingly, it is now well accepted that asymptomatic individuals are contributing to the spread of COVID-19, with estimates suggesting that nearly 60% of all spread occurs in this manner. This percentage will likely vary, depending again on the probabilities outlined above. Nevertheless, since asymptomatic individuals are not sneezing or coughing, this provides further support that normal breathing and talking, along with singing, leads to transmission and is further evidence for the role of smaller aerosols in driving this pandemic. Microscopic aerosols can travel beyond 6 feet, and this needs to be carefully considered in the transmission of COVID-19. This is critical, because it means that the closer you are to inhaling the air that someone else exhales, the higher your probability of getting infected. This may also mean you are not safe if you are more than 6 feet away, especially indoors with poor air circulation. An elegant contact tracing experiment in South Korea recently provided evidence that one can be infected, even when on the other side of a restaurant, when individuals were not wearing masks, and air flow carried these tiny aerosols across the room.

So, while hand-washing is good hygiene that should be encouraged, this is a respiratory virus spread largely by aerosols, and the probability of getting live virus from your hands or a surface into your respiratory tract appears small. COVID-19 transmission can be dramatically curtailed with mask wearing, which children generally don’t mind, and once their teachers are vaccinated, the risk of COVID-19 spread to the students and vice versa drops significantly. Regardless, it is important for our politicians to remember that our teachers should be treated with respect as we make these critical decisions.

Chris Janetopoulos is an associate professor of biological sciences and co-director of the BioImaging Core Facility at the University of the Sciences in Philadelphia. Email: c.janetopoulos@usciences.edu

Get local stories you won't find anywhere else right to your inbox.
Sign up here

Just Posted

Langley RCMP officers and Langley School District employees marked a rainbow crosswalk at 48A Avenue and 222 Street on Wednesday, Feb. 24, for Pink Shirt Day. (Ryan Uytdewilligen/Aldergrove Star)
VIDEO: Langley School Board reaches fundraising goal for rainbow crosswalk

RCMP officers and school district staff marked the upcoming rainbow crosswalk on Pink Shirt Day

The development plan for a proposed Willoughby building showing a possible library site. (Pollyco/Special to the Langley Advance Times)
Langley Township council says no to delay in considering Willoughby library

One councillor called for a system-wide review before making a decision

Langley sister Shannon Obando, 35, and Jen Spier, 29, started Hope in a Box, which features items from local small businesses, to fundraiser for non-profit Hope International. (Special to Langley Advance Times)
Langley sisters Hope in a Box fundraiser: local products with global impact

All proceeds will benefit non-profit Hope International

Christian Burton is not a cold-weather kind of athlete, but he took the plunge anyway, getting dunked to help raise funds for Special Olympics. (Special to Langley Advance Times)
VIDEO: Langley’s Christian Burton takes the plunge for Special Olympics

A freezing dip in a kiddie pool to raise money for athletes

A new Fraser Valley food hub in Abbotsford will include shared kitchen space that can be accessed by small and medium-sized businesses. (Stock photo by Robyn Wright from Pixabay)
Almost $2M to support new Fraser Valley food hub in Abbotsford

Project being developed by District of Mission and Mission Community Skills Centre

Dr. Bonnie Henry talk about the next steps in B.C.'s COVID-19 Immunization Plan during a press conference at Legislature in Victoria, B.C., on Friday, January 22, 2021. THE CANADIAN PRESS/Chad Hipolito
456 new COVID-19 cases in B.C., 2 deaths

Since January 2020, 78,278 have tested positive for the novel coronavirus in B.C.

A health-care worker prepares a dose of the Pfizer-BioNTech COVID-19 vaccine at a UHN COVID-19 vaccine clinic in Toronto on Thursday, January 7, 2021. (THE CANADIAN PRESS/Nathan Denette)
Vaccinating essential workers before seniors in B.C. could save lives: experts

A new study says the switch could also save up to $230 million in provincial health-care costs

Cannabis bought in British Columbia (Ashley Wadhwani/Black Press Media)
Is it time to start thinking about greener ways to package cannabis?

Packaging suppliers are still figuring eco-friendly and affordable packaging options that fit the mandates of Cannabis Regulations

The late Michael Gregory, 57, is accused of sexually exploiting six junior high students between 1999 and 2005. (Pixabay)
Former Alberta teacher accused of sexually assaulting students found dead in B.C.

Mounties say Michael Gregory’s death has been deemed ‘non-suspicious’

A woman boards a transit bus through rear doors, in Vancouver, on Friday, March 20, 2020. THE CANADIAN PRESS/Darryl Dyck
TransLink slow to reveal crucial details about ransomware attack, says union

Union says company took months to admit what info was stolen, including SIN and bank account details

According to a new poll, a majority of Canadians want to see illicit drugs decriminalized. (THE ASSOCIATED PRESS)
Majority of Canadians think it’s high time to decriminalize illicit drugs: poll

More than two-times the B.C. residents know someone who died from an overdose compared to rest of Canada

VIDEO: Lynx grabs lunch in Kamloops

A lynx surprises a group of ducks and picks one off for lunch

(Black Press Media file photo)
B.C. residents can reserve provincial camp sites starting March 8

B.C. residents get priority access to camping reservations in province

Most Read