The World Health Organization (WHO) has renamed the multiple different strains of COVID-19 circulating around the world to make them easier to understand.
Under the changes, the four most concerning variants take on the first four letters of the Greek alphabet — Alpha, Beta, Gamma, and Delta. Those were previously known as the UK variant, the South African variant, the Brazilian variant, and the Indian variant.
What is The Delta Variant?
The Delta variant is the most recently designated variant of concern, as classified by the WHO. That means it's one of the four variants most concerning to global health authorities because it's believed to show: increased transmissibility or detrimental change in epidemiology, increased virulence or change in disease presentation, decreased effectiveness of prevention and control measures.
The Delta variant was first detected in India in October last year and is considered highly contagious. Its other names include B.1.617.2 and the Indian variant.
The Kappa Variant
The Kappa variant is the one behind most of the cases in Victoria.
It likely entered the Victorian community via a man who became infected in hotel quarantine in Adelaide before traveling to Victoria. It was also first detected in India, but unlike the Delta variant, it's not listed as a variant of concern.
Instead, the WHO treats it as a variant of interest. However, it is still highly contagious and potentially deadly. Its other name is very similar to the Delta variant: B.1.617.1.That's because they originated from the same strain: B.1.617
The Fast-spreading Covid Variant
The WHO said the Delta variant had been detected in more than 80 countries and it continues to mutate as it spreads. Labs around the world that analyse the virus's genetic material have been sharing their findings to a global database. When you look at this, the UK looks like it has more cases of the Delta variant than most of the rest of the world.
The version of the virus played a significant role in a record-setting surge of infections that overwhelmed India’s healthcare system. It has become the dominant variant in the U.K., accounting for 96% of samples sent for genetic analysis in the final week of May. After cases of the variant surged, Prime Minister Boris Johnson delayed by four weeks the country’s plans to drop all remaining Covid-19 restrictions in late June.
The variant now makes up 10% of all new cases in the United States, up from 6% last week. The Delta variant of Covid-19 is expected to become the dominant strain in the United States, and it's further reason why people need to ramp up the vaccination pace.
The delta variant is more transmissible than the “alpha” variant (previously known as the U.K. or Kent variant which was itself much more transmissible than the original version of the virus) and is more likely to lead to hospitalizations, as has been seen in countries like the U.K.
The Delta variant's increased transmissibility could allow it overtakes the Alpha variant, first identified in the United Kingdom, in the US in the coming months. Delta cases are rising “exponentially” and the “resurgence” of Covid-19 infections in England was “associated with increased frequency of Delta variant. Most infections are happening in children and young adults, but they are rising in older people too.
The Pfizer/BioNTech and Moderna vaccines offer good protection against the variant — after the second dose. And studies are underway now to examine Johnson & Johnson. Spreading variants shouldn't be a concern to those who are vaccinated.
Immunity might fade for protection against mild disease or asymptomatic infection or low moderate disease, protection against critical disease will probably be relatively long-lasting. The so-called cellular immune response induced by these vaccines appears to be excellent. We still can't say for sure how long the protection will last. Their durability will determine whether the population will need boosters.
How Infectious is The Delta Variant?
Data from the UK showed that the Delta variant was more infectious than other variants. Delta variant may be up to 60% more infectious than the UK variant, Alpha, so that makes it up to twice as infectious as the original Wuhan strain. Delta spreads more easily among children than other variants.
To think about the infectiousness we consider the R0 value, or how quickly the virus spreads if there are no mitigating measures such as distancing, masks, or restrictions. The Wuhan strain had an R0 value of around 2.5, the Alpha strain was about 3.75 and the Delta strain was about 5. That means if we were living life like we were in 2019, one person with the Delta strain would likely infect five other people, compared to just 2.5 last year. The Kappa strain was slightly less infectious than the Delta strain.
Delta Variant Affects People Differently
Evidence is still emerging about the severity of the Delta variant, but there are anecdotal reports of greater severity of illness in children compared to earlier strains. People were more likely to require hospital treatment when infected with the Delta strain, compared with the Alpha strain. Infected persons are more than twice as likely to be hospitalized if they have that variant and 1.6 times as likely to be in an emergency department within two weeks of having an infection.
Symptoms
The classic signs of coronavirus reported since the start of the pandemic have been loss of smell or taste, a new persistent cough, and a fever, but these are less common now. A headache, sore throat, and runny nose are now thought to be symptoms of the virus, instead of a cough and loss of smell or taste - though a fever is still common.
A headache is now the most reported symptom, followed by sore throat, runny nose, and fever. A cough is even rarer, coming in at the fifth most reported symptom and loss of taste or smell doesn't even make it into the top 10.
For the younger population, contracting COVID-19 feels more like a "bad cold" leading some to still go out to parties and spread it to around six other people. This is a very sticky virus and it is explaining in a way why it has done so much damage in such a short time.
Fatality rates for the Delta variant remain very low though - 0.1 %, compared to 1.9% for the Alpha, or Kent variant. Delta is up to 60% more transmissible than the Alpha variant, B.1.17.
Why is it more contagious?
Delta has a key mutation on the spike protein – which the coronavirus uses to latch on to human cells – called L452R. This was also detected in a variant spreading in California earlier this year and is thought to explain why the variant spreads more easily.
The virus appears "fitter" than previous variants. From data collected in the lab, it looks like Delta's mutations make it spread more easily in the cells in a person's airways, which means an inpidual is likely to emit more viruses when infected.
How to Protect From The Delta Variant?
Rules like keeping a distance of 1.5 meters, washing hands, wearing masks, and ventilation protect against all known variants of the coronavirus including Delta.
Traveling to so-called virus-variant areas should be avoided as it has increased the spread of the coronavirus and its variants since the beginning of the pandemic. That is why comprehensive quarantine rules are needed.
Public health and social measures need to be used strategically and must be supported by governments, communities, and inpiduals to stop all variants of the virus.
Will we need booster doses against it? This is currently unknown, but it should become clearer as Delta continues to spread and more people receive additional doses of COVID-19 vaccines. Laboratory studies on the ability of vaccine-induced antibodies to neutralize the virus, post-booster dose, should also help to answer this important question.
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