One in six English cases is caused by Covid’s Delta subvariant. It is expected to become dominant within months.

The AY.4.2 strain is about 10 to 15% more contagious than the Delta virus, which is already extremely virulent. The current rate is around 2 percent per week. 

According to the Sanger Institute (the largest surveillance centre for variants in the country), AY.4.2 was responsible in England for 16% of the new cases between November 13 and December 13. 

Experts predict that it will soon be the dominant player in England, and could even surpass Delta in the UK in January.

Last week, a government-funded study found that this new strain of Covid is less likely to cause disease. The UK might be able to manage a milder version next year. 

Nearly two-thirds (66.7%) of people who have AY.4.2 are affected, as compared to the three-quarters (76.4%) who suffer from regular Delta. 

The virus is thought to be from London, or South East England. It has two slight modifications to spike protein which it uses to enter the cells.

Scientists still don’t know if this subvariant has a higher biological infection rate than its predecessor strain, or whether it infects more people who are vaccinated. 

Professor Jeffrey Barrett of the Sanger Institute is responsible for sequencing and stated that the subvariant would be dominant by January.   

Below is a graph showing the total number of variants that were identified in the year. To become the dominant strain, the Indian variant ‘Delta’ replaced the Kent version ‘Alpha’ in May.

The above graph shows the proportion of infections sparked by different strains in England. The Indian 'Delta' variant is green, AY.4.2 is maroon, and the Kent 'Alpha' variant is purple. The dark green and pink areas represent the old virus

This graph displays the incidence of different strains of infection in England. The Indian variant ‘Delta’ is green and AY.4.2 maroon. While the Kent variant ‘Alpha’ is purple. These areas are the remnants of an old virus.

NOVEMBER 13: This map shows the proportion of cases that were AY.4.2 in the fortnight to November 13. A darker colour means the subvariant was behind a higher proportion of cases. It was only behind more than 50 per cent in Torridge, Devon

NOVEMBER 6: This map shows the proportion of cases that were AY.4.2 in the fortnight to November 6. A darker colour means the subvariant was behind a higher proportion of cases. It was only behind more than 50 per cent in Torridge, Devon

These maps display the percentage of cases that were initiated by AY.4.2 between Novemebr 13, and Novemebr 6, respectively. The subvariant responsible for a larger proportion of cases is indicated by a darker color.


AY.4.2. Everything You Need to Know 

What is the origin of AY.4.2?

The UK-based tracking revealed that this sub-variant was first discovered in Delta on June 26, 2012.

Researchers believe that AY.4.2 originated in the UK, as there are more cases than any other country.

However, it’s possible the variant may have been imported from outside and spread throughout the country.  

What is the infectious potential of the subvariant?

Experts have estimated that AY.4.2 has around 10 percent more infection than its Delta counterpart.

This may result in a slightly higher number of cases but it won’t cause a spike like the one seen after Delta entered the UK.  

What should I do about AY.4.2

According to scientists, there’s no need for concern about AY.4.2.

No evidence has been found to indicate that sub-variants of vaccines have a lower effectiveness or increase mortality.

To assess the situation, however, lab tests in Denmark and UK are being conducted. 

Professor Lawrence Young of Warwick University said that vaccines will be just as effective.

Anders Fomsgaard, a professor at Denmark’s Covid surveillance center said that he was not worried about this. There is nothing that suggests it may be more infectious, resistant, or dangerous at this time.

AY.4.2 was discovered for the first time in the UK on June 2, and it has slowly been spread to other parts of the country.

Up to now, 44,812 cases in the country have been identified, which includes 5,329 in Scotland as well as 5,782 from Wales.

It is believed that the South East or London was where it appeared first, although there isn’t any clear evidence to support this belief. 

Two key mutations are present in the virus, A222V, and Y145H. These changes only slighty alter the structure of spike proteins that the virus uses as a weapon against cells.

Scientists say A222V has been previously seen on B.1.177, a different variant of A222V. This was first discovered in Spain and then spread to other countries. 

Studies have shown that this did not increase the transmission of the strain and that only holidaymakers spread it.

The mutation Y145H is a concern. It slightly changes how the antibodies bind to the site, making it difficult to stop infection. 

This mutation could be due to genetic changes in Delta and make it more resistant than the parent.

AY.4.2 is a registered disease in 40+ countries. There have also been approximately 45,000 instances worldwide.

The Sanger’s weekly surveillance figures also highlighted another Delta off-shoot — AY.4.2.1 — which is gradually increasing in frequency. 

The latest two-weeks saw 2.7% increase in cases, up from 2.0% previously. 

There are more than a hundred different AY lineages — offshoots of the Delta variant — and the vast majority are not concerning.

Delta, being so dominant and virulent, will undergo many mutations in its spread through the population. However, not all of them will be significant. 

However, some people develop an evolutionary advantage by being resistant or more transmissible to vaccines. 

It comes after the REACT study  — which measures the spread of the virus in England based on more than 100,000 swab tests — found the subvariant is ‘less likely to be associated with symptoms’. 

Imperial College London researchers behind the study said just two-thirds of people who tested positive for AY.4.2 reported coronavirus symptoms, such as a loss or change to smell or taste, a fever or persistent cough.

Meanwhile, three-quarters of people who caught an older version of Delta — called AY.4 — suffered the tell-tale virus symptoms. Experts predict that the UK will gradually become more affected by the milder strain. 

The subvariant’s week growth rate was between one percent and two percent according to separate data from the UK Health Security Agency, which replaces the defunct Public Health England. 

Scientists predicted previously that Covid would become a flu-like strain of virus. However, it doesn’t cause any severe illnesses or deaths.

Meaghankall, an epidemiologist from the UKHSA stated that AY.4.2’s “advantage of infectiousness means it’ll become the predominant strain.” 

She claimed that subvariant does not differ from original Delta strains in any way that would be a concern. 

Ms Kall explained that the condition is slow-moving and growing at one to two percentage points per week. 

If it continues to grow at the current pace, it may be dominant by March.

Paul Hunter, an infectious diseases expert at the University of East Anglia, said the coronavirus will likely reach a stable point over the next few years, where it would continue to spread but not cause severe disease.

He said that the virus would be an endemic disease, which means it won’t be eliminated, and people will slowly build up natural immunity, so symptoms may resemble a common cold. 

He said, “The virus and we will find an equilibrium” and that the equilibrium would not contain many deaths or severe cases within very few years.