What is the reason for the rapid spread of the Delta variant and what does it mean for Canada?

The Delta variant, first discovered in India in late 2020, has spread worldwide and now represents the majority of cases in Canada and various other countries.

The recent spread in the United States has led the U.S. Centers for Disease Control and Prevention (CDC) to recommend that Americans wear masks in areas with substantial transmission “regardless of vaccination status.”

So, why is this particular variant spreading so quickly?

There are still unknowns about exactly how the Delta variant manages to spread at such a rapid pace. But we are getting closer to understanding how it works.

The Delta variant is believed to be significantly more contagious than the early strain of SARS-CoV-2, the virus that first swept the world. The World Health Organization (WHO) has described Delta as a distinct concern. Dr. Michael Ryan, WHO’s executive director of the Health Emergencies Program, said during a press briefing on Friday: “We are fighting the same virus but it is a virus that has become fitter and better adapted for transmission between us humans.”

Scientists estimate it spreads about 50 percent faster than the Alpha variant, which was itself 50 percent more infectious than the original virus strain, according to the Yale School of Public Health.

This means each infected person can transmit the virus to more people than before, helping this variant spread quickly among populations—and even faster among those whose immune systems are not already on high alert due to a previous COVID-19 infection.

How widespread is the Delta variant?

This variant has definitely spread worldwide since it was first reported in October 2020 in India, where other countries later reported high levels too.

Shane Crotty, a virologist at the La Jolla Institute for Immunology in San Diego, told Reuters, “It outcompetes all the other viruses because it spreads much more efficiently.”

In the United States, Delta now accounts for more than 80 percent of new infections. Cases are also rising in many areas with low vaccination rates, with data showing that unvaccinated individuals make up about 97 percent of all severe cases.

The World Health Organization announced in late July that the variant is now present in at least 26 African countries, with 21 countries seeing case increases of more than 20 percent for at least two weeks.

So what does all this mean for Canada?

There is now increasing evidence that the speed at which Delta spreads could cause another overall rise in cases—although nearly six out of ten Canadians are now fully vaccinated, millions remain unprotected.

Ontario and Quebec have largely stabilized in terms of new daily COVID-19 cases after weeks of declining numbers, while new cases have continued to double daily in British Columbia over the past three weeks.

The virus is also spreading in Alberta faster than during the peak of the third wave in the province—all while that province prepares to ease its strictest mask-wearing and isolation requirements.

Even if this variant begins to spread generally across Canada, some experts hope Canada as a whole can avoid the more severe outcomes, including the huge strain on hospital networks and death tolls seen in previous waves.

Angela Rasmussen, a virologist at the Vaccine and Infectious Disease Organization at the University of Saskatchewan, said most people can avoid getting infected with this variant if they are fully vaccinated and follow preventive measures, although she expects outbreaks in schools if mitigation measures are not applied.

Meanwhile, epidemiologist Ryota Dyonandan from the University of Ottawa emphasized that many Canadians are still wearing masks and taking precautions in social settings, saying, “I am somewhat optimistic... if we continue to do this, we can be world leaders in health protocol implementation.”