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Delta ‘fastest and fittest’ of COVID variants

Andrea King

Delta ‘fastest and fittest’ of COVID variants
COVID Variants (GP)

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The Delta variant of COVID-19 will definitely accelerate the pandemic.

This is the view of Yale Medicine epidemiologist Dr F. Perry Wilson, who said the uniqueness of this strain of the virus is how quickly it is spreading.

The first Delta case was discovered in India in December 2020, and quickly became the dominant strain there and in Great Britain. The Centre for Disease Control and Prevention (CDC) estimates that by the end of June, more than 20 per cent of the cases in the USA were of that strain. Medical experts agree that the Delta strain is more contagious than the other virus strains.

In mid-June, the CDC labelled Delta as “a variant of concern,” using a designation also given to the Alpha strain that first appeared in Great Britain, the Beta strain that first surfaced in South Africa, the two Epsilon variants first diagnosed in the US, and the Gamma strain identified in Brazil, writes Kathy Katella.

The new naming conventions for the variants were established by the World Health Organisation (WHO) at the beginning of June as an alternative to numerical names.

According to, the World Health Organisation called this version of the virus “the fastest and fittest”.

“It’s actually quite dramatic how the growth rate will change,” says Dr Wilson. Delta is spreading 50 per cent faster than Alpha, which was 50 per cent more contagious than the original strain of SARS-CoV-2, he told

“In a completely unmitigated environment – where no one is vaccinated or wearing masks – it’s estimated that the average person infected with the original coronavirus strain will infect 2.5 other people,” Dr Wilson says. “In the same environment, Delta would spread from one person to maybe 3.5 or other people.”

People who have not been fully vaccinated against COVID-19 are most at risk, especially young people.

“As older age groups get vaccinated, those who are younger and unvaccinated will be at higher risk of getting COVID-19 with any variant,” says Dr Yildirim, Yale Medicine paediatric infectious diseases specialist and a vaccinologist. “But Delta seems to be impacting younger age groups more than previous variants.”

Even as the Delta strain has been present for seven months, there is still much to learn about it. Research is ongoing into whether people will be more ill than with the original virus.

Delta ‘fastest and fittest’ of COVID variantsKatella states there have been reports of symptoms that are different than those associated with the original coronavirus strain. It is also unclear if the Delta strain could cause more infections in people who were vaccinated or have natural immunity from a prior COVID-19 infection.

It is also too soon to know whether a booster modified to target the Delta variant will be needed. Experts also do not yet know if vaccinated people will need an additional shot at some point to boost the overall immunity they got from their first shots.

“It seems like cough and loss of smell are less common symptoms. And headache, sore throat, runny nose, and fever are present based on the most recent surveys in the UK, where more than 90 per cent of the cases are due to the Delta strain,” Dr Yildirim says, adding the risk of infection is significantly lower than in someone who has not been vaccinated.

Doctors advise that vaccination is the best protection against the Delta variant of COVID-19.

“Like everything in life, this is an ongoing risk assessment,” Dr Yildirim said. “If you are in a crowded gathering, potentially with unvaccinated people, you put your mask on and keep social distancing. If you are unvaccinated and eligible for the vaccine, the best thing you can do is to get vaccinated.”

“From what we know so far, people who are fully vaccinated against the coronavirus appear to have protection against Delta, but anyone who is unvaccinated and not practising preventive strategies is at risk for infection by the new variant,” Dr Wilson added.  (AK)

This article is brought to you by Better Health Magazine.