British COVID variant 45% more contagious, Israeli study finds
The British variant of the SARS-CoV-2 (called B.1.1.7) is 45% more infectious than the original wild strain that first appeared in China a year-and-a half ago, according to researchers at Tel Aviv University (TAU). This variant has caused almost all of the infections in Israel and in many parts of the world.
However, the team found that fortunately, the mRNA vaccines (Pfizer and Moderna) have proven effective against both the original strain and the British variant.
The researchers compared the R (basic reproduction number) of the original SARS-CoV-2 virus with the R of the British variant and found that the British variant is almost 1.5 times more infectious. “Our study proves that active monitoring of at-risk populations and prioritized vaccination programs can prevent many deaths.”
The researchers — Prof. Ariel Munitz and Prof. Moti Gerlitz of the department of clinical microbiology and immunology at TAU’s Sackler Faculty of Medicine, together with Dr. Dan Yamin and doctoral student Matan Yechezkel from the Laboratory for Epidemic Modeling and Analysis (LEMA) in the industrial engineering department, used data from about 300,000 PCR (polymerase chain reaction) tests for Covid-19 obtained from the COVID-19 testing lab, which was established in collaboration with the Electra Group.
The study’s results were published in the prominent scientific journal Cell Reports Medicine under the title “BNT162b2 Vaccination Effectively Prevents the Rapid Rise of SARS-CoV-2 Variant B.1.1.7 in high-risk populations in Israel.”
The Electra-TAU laboratory was established in March of last year, just after the outbreak of the first wave of the pandemic in Israel. To date, it has analyzed hundreds of thousands of tests from all over the country – including public drive-in test facilities, as well as programs targeting specific populations such as ‘Shield for Fathers and Mothers’ that routinely ran tests in at-risk hotspots like retirement homes.
(From Left to right)- Prof. Ariel Munitz Dr. Dan Yamin Prof. Moti Gerlitz (Photo credit: Tel Aviv University)
“We use a kit that tests for three different viral genes,” recalled Munitz. “In the British variant, one of these genes – the S gene – has been erased by the mutation. Consequently, we were able to track the spread of the variant even without genetic sequencing.”
The data from the lab, he continued, showed that the spread of the British variant was very quick. On December 24, 2020 only five percent of the positive results were attributed to the British variant. Just six weeks later, in January, 2021, this variant was responsible for 90% of Covid-19 cases in Israel. The current figure is about 99.5%.
“To explain this dramatic increase, we compared the R number of the SARS-CoV-2 virus with the R of the British variant. In other words, we posed the question: How many people, on the average, contract the disease from every person who has either variant? We found that the British variant is 45% — almost 1.5 times – more contagious.”
In the study’s second stage, the researchers examined contagion by age groups. The results indicated that the turning point for the 60+ population compared to other age groups occurred two weeks after 50% of Israel’s 60+ population received their first vaccine shot.
“Until January we saw a linear dependence of almost 100% between the different age groups in new cases per 1,000 people,” added Yamin.
“Two weeks after 50% of the 60+ population received the first dose of the vaccine, this graph broke sharply and significantly. In January, a dramatic drop was observed in the number of new cases in the 60+ group, alongside a continued rise in the rest of the population. Simply put, since more than 90% of those who died from Covid-19 were over 60, we can say that the vaccine saved hundreds of lives – even in the short run.”
Moreover, the new study proves that active monitoring of at-risk populations works. “There is a threshold value for determining whether a specific test is positive or negative for the virus – with a lower value indicating a higher viral load,” explained Munitz. “When we compared the threshold values of the different genes in 60+ residents of retirement homes with the values measured in 60+ persons in the general population, we saw significantly higher values in the retirement homes. This means that the viral load in retirement homes was lower compared to the rest of the population.”
Since the elderly in retirement homes are tested routinely, while other people are usually tested only when they don’t feel well or have been in contact with someone who had tested positive for the virus, “we conclude that constant monitoring of at-risk populations is a method that works. It is important to emphasize: the relatively low viral load was found in retirement homes despite the fact that the British variant had already begun to spread in all populations. Consequently, we show that monitoring retirement homes, together with vaccination that gives precedence to vulnerable populations, prevent illness and mortality” Munitz declared.
Due to crowded conditions, large households and age distribution in the Israeli population, the coronavirus had a more favorable environment for spreading in Israel compared to most Western countries. “Our message to the world is that if with our problematic starting point a distinct decline was identified, other Western countries can certainly expect the curve to break – despite the high contagion of the British variant – with a dramatic drop in severe cases following the vaccination of 50% of the older population, alongside targeted testing at risk epicenters.”
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