As COVID-19 variants spread, why are global coronavirus cases decreasing?

© EPA / ANDY RAIN
epa09021303 A hospital team passes through a Covis-19 mobile test center in London, Great Britain, on February 18, 2021. Information published on February 18, 2021 in the React study at Imperial College London states that hospital admissions and deaths caused by Covid-19 are decreasing significantly. The British government hopes that schools will be able to reopen in early March and that blocking restrictions may begin to be lifted. EPA / ANDY RAIN

In an encouraging sign for the COVID-19 pandemic, the number of new coronavirus cases worldwide and in Canada continues to fall this year.

For the fifth consecutive week, the World Health Organization (WHO) reported a decline in new infections on Wednesday. With a 16 percent reduction from the previous week, 2.7 million new cases were documented last week, the WHO said. The number of new deaths has also dropped 10 percent.

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“There has been a significant and global drop in the disease, week after week, for the past four or five weeks. We didn’t see levels as low as they did last October, ”Mike Ryan, executive director of the WHO health emergency program, said at a news conference on Monday.

Nationally, Canada has seen a steady drop in the daily case count, with a seven-day average of 2,886 new daily cases reported for the week of February 11-17.

“We have reason to be hopeful and I hope everyone is a little comfortable with the fact that we can reduce transmission … with our actions at the individual level, if we are able to do so,” Maria Van Kerkhove, technical leader WHO for COVID-19, said on Monday.

Video: COVID-19 active cases decreasing in all areas of the province, except one

Experts believe that a number of factors, including adherence to public health guidelines, strict roadblocks and reduced travel, are likely to contribute to the downward trend in cases.

Some studies suggest that the launch of highly effective vaccines may also be playing a role.

A new study published in the medical journal Lancet on Thursday found that among the 7,214 hospital employees in Israel who received their first dose in January, there was an 85 percent reduction in symptomatic COVID-19 within 15 to 28 days, with a general reduction in infections, including asymptomatic cases detected by tests, of 75 percent.

On Thursday, Dr. Howard Njoo, Canada’s deputy head of public health, said there are “early indications” that coronavirus vaccines are having an impact on infection rates.

Read More: Pfizer’s COVID-19 vaccine reduces virus transmission, according to Israeli studies

After more than a year of pandemic, partial immunity between populations and the natural seasonal effect commonly seen during epidemics that show a wave pattern may also be reducing the spread, according to Dr. Prabhjot Singh, chief medical and scientific consultant from CV19 CheckUp and associate professor at the Icahn School of Medicine at Mount Sinai, New York.

“Often, outbreaks follow a bell-shaped curve, which means that they infect many people and then have problems because of immunity in less susceptible hosts, so cases decrease, until more susceptible hosts are available, ”said Dr. Amesh Adalja, senior scholar at the Johns Hopkins Center for Health Security.

In the United States, which has by far the largest number of cases in the world, new weekly cases dropped from 1.7 million at the national peak in early January to less than 600,000 this week, according to the COVID Tracking Project. He also noted that new cases have declined in all states.

Dr. Martin Makary, a professor at the Johns Hopkins School of Medicine, argues that the country will achieve collective immunity in April.

Read More: It is ‘unknown’ when Canada will achieve collective immunity from the coronavirus vaccine: Tam

“As more and more people are infected, there are fewer people susceptible to the infection,” he told Global News.

“And in most parts of the world, collective immunity has started to take effect.”

According to the WHO, herd immunity is when a population can be protected from a certain infectious disease, such as COVID-19, either through vaccines or immunity developed by previous infection.

“The herd’s immunity against COVID-19 must be achieved by protecting people through vaccination, not exposing them to the pathogen that causes the disease,” says the WHO.

India has the second highest number of COVID-19 infections. The Indian government has partly attributed the dramatic drop in cases to the use of masks, which is mandatory in public in India and the violations result in heavy fines in some cities.

Adalja said that if “herd immunity” is achieved in a subpopulation that is causing infections, it can have “cascading benefits” in general cases.

Video: Experts try to understand India’s sharp drop in COVID-19 cases

The global decline comes in the context of a spread of new, more contagious variants that are rapidly overcoming the original SARS-CoV-2 virus to become the dominant strain in some countries.

In the United Kingdom, where a blockade was imposed on January 4 to combat the new, rapidly spreading variant B.1.1.7, infections have fallen by more than two-thirds since last month. An interim report tracking monthly numbers was released by researchers at Imperial College London on Thursday.

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Adalja said the new variants still spread in the same way and can be blocked using the same public health measures that are in place.

The national modeling released on Friday emphasized the looming threat of the variants, with Canadian health officials warning that the pandemic could “quickly resurface” if public health measures are lifted.

Recent modeling from Quebec and Ontario also suggests that variant B.1.1.7, first detected in the UK, may dominate in a matter of weeks.

Jean-Paul Soucy, an infectious disease epidemiologist and doctoral student at the University of Toronto, told Global News that as soon as the new variants replace the old one, Canada could see an increase in cases that could trigger a third wave in the country.

Read More: Booster injections, new clinical trials – What COVID-19 variants could mean for vaccines

But pointing to the example of the UK, he said that the “good news” is that we can suppress the growth of variants with “traditional measures” – blocking, masking, hand washing and physical distance.

Singh said the spread of new variants raises concerns that an increase may be coming, but the decline in cases offers an opportunity to prepare for the coming months.

“There are real declines – and it’s a chance to double what works and prepare for the potential of another wave. “

– With files from Reuters, The Associated Press.