COVID-19 cases rise when schools open – but more so when teachers and students don’t wear masks
As students return to schools in Victoria and New South Wales after months of closure, many people can worry about the risks to their children – and transmission in general.
The role schools play in transmitting the virus that causes COVID-19 has been difficult to determine, but new evidence may finally answer this question. Schools amplify community transmission, but the good news is that some relatively simple mitigation measures can make schools much safer.
What the new evidence says about opening schools
A new study conducted in the United States found that reopening schools in late 2020 was associated with an increase in COVID-19 cases and deaths.
Part of the increase can be attributed to other restrictions relaxed at the same time and the ability for parents to return to the workplace, where transmission also occurs.
Most importantly, cases and deaths increased the most in counties where students and teachers did not have to wear masks to school.
We shouldn’t be surprised at this finding, as face masks are one of the most effective ways to prevent the spread of COVID-19. A school outbreak investigation, supported by the US Centers for Disease Control (CDC), found that schools without an indoor mask requirement were 3.5 times more likely to have an outbreak that schools in which students and staff were required to wear masks.
This is why the CDC recommends indoor universal masking by all children two years of age and over, as well as teachers and school visitors, whether or not they are vaccinated.
More evidence to support masks in schools
One of the reasons it has been difficult to see transmission in schools is that children usually have mild symptoms. This leads to infections which go undetected. But the picture is very different when researchers are actively looking for cases.
Read more: Can’t get your child to wear a mask? Here are 5 things you can try
Belgian researchers carried out a to study where elementary school students and their teachers were tested once a week for 15 weeks. They found numerous cases of transmission between children and adults that spread beyond school to parents of children and partners of teachers. Some mitigation measures were in place in the school, but no mask was worn.
Other measures also help
Perhaps the most dramatic example of failure to protect schools comes from England. Schools reopened in September without a mask mandate and with very little investment in ventilation.
In a month, random tests have shown that 8% of secondary students and 3% of pre-primary and primary students had an active infection.
This happened despite more than 80% people aged 16 and over who have received two doses of the vaccine. As a result, infections in adults were much lower – around 1% or less across all age groups.
This clearly shows that high levels of immunization in adults are not enough to protect children, as children easily pass the virus to each other.
Read more: We may need to vaccinate children as young as 5 years old to achieve herd immunity with Delta, according to our modeling
It also shows that infections in children do not simply reflect overall community transmission. Schools play a key role in amplifying the spread of COVID-19.
Why we need to protect children
We need to prevent infections in children for a number of reasons. First, although most children with COVID-19 suffer from mild illness, a small proportion get sick enough to require hospitalization.
It might not seem like a big deal, but we can expect almost all of Australia’s 3.8 million children to end up getting infected if we don’t vaccinate them. A small proportion of this is a large number, and could easily overwhelm children’s hospitals, which is what happened in the United States.
Children who contract COVID-19 may also end up with persistent symptoms, known as COVID-19. It is not known exactly how often this occurs, but the condition is common enough that England’s National Health Service has implemented 15 long COVID clinics for kids. In Israel, long COVID clinics have long waiting lists.
Read more: No, we can’t treat COVID-19 like the flu. We must consider the lasting health problems it causes
High levels of transmission in children also lead to disruption in education. Two weeks after returning to England, more than 100,000 children were absent from school due to confirmed or suspected COVID-19.
And children can easily pass the coronavirus to other children and adults. This will lead to parents and other members of the wider community to fall ill, including some vaccinated people.
Although COVID-19 vaccines are very effective in preventing serious illness, they are not perfect and breakthrough infections can occur. To minimize breakthrough infections, we need to keep community transmission low.
Here’s how to make schools safer
It’s not difficult to make schools much safer places, but it does require a greater emphasis on cleaning the air rather than cleaning our hands. This is because COVID-19 is caused by a airborne virus which can drift through the air like cigarette smoke.
The OzSAGE Independent Scientific Advisory Group was recently launched comprehensive advice on how to prevent this type of transmission in schools.
OzSAGE recommends immunizing children, their parents and teachers as soon as possible; increase ventilation and use HEPA air filters purify indoor air; and ensure that masks are worn by all staff and children who can safely wear them.
Read more: From vaccination to ventilation: 5 ways to protect children from COVID when schools reopen
These measures will likely have benefits beyond the pandemic. Clogged air in classrooms is not good for learning, and school performance has been shown to improve with ventilation.
Clean air is an investment in the future of our children.