Infectious Diseases Data Verified

AY.4.2 Delta Variant

Published on Nov 03, 2021   -  4 min read


One more Delta variant of the coronavirus has been in the news lately. This article discusses the AY.4.2 Delta variant in detail.



The day does not start and end without information on the recorded number of COVID cases and deaths for the day. This is how the pandemic has changed our lives and is still prevailing without an end. Until we all get vaccinated, maybe a day will come where the media would report the number of COVID variants rather than the cases. The latest one is the AY.4.2 Delta variant. With the advent of this sub-lineage of the Delta variant, panic rises for the third COVID wave worldwide. This article explains whether or not this Delta variant is deadly and the vaccine’s efficacy against the variant.

What Is AY.4.2?

This is a sub-variant or strain of the Delta variant of the original coronavirus. This AY.4.2 COVID variant was initially identified in the United Kingdom. Though there are no abrupt surges in the COVID cases, the United Kingdom has been observing a gradual increase in the number of affected cases. There are at least 75 AY lineages of the Delta variant identified as of now, of which the AY.4.2, a sub-lineage of the AY.4, has gained attention due to few rise in the cases worldwide.

What Variant Is AY.4.2?

As of October 27, 2021, the AY.4.2 Delta variant is not categorized under any of its variants by the World Health Organization (WHO). While the Delta variant continues to be the dominant variant causing a surge in COVID cases since the second wave, the AY.4.2 is considered to be a sub-lineage of the Delta variant of the coronavirus.

Why Did the AY.4.2 Delta Variant Develop?

Viruses replicate and mutate throughout their lives. Based on the type of mutation, they may or may not become a dominant strain. To escape the host immune effects, these viruses keep on mutating. Mutations are slight changes in the virus’ genes that occur during replication. Some mutations make it more powerful and some less. The more it gets transmitted, the more mutations it acquires. Two new mutations in the genome of the SARS-CoV-2 have been known to occur every two weeks since it was first discovered.

And the AY.4.2 Delta variant is a similarly mutated newer variant of the coronavirus. Its effects on the human population are still not fully evident. The exact location of the mutation in the virus is responsible for its virulence, transmissibility, and ability to evade protection. The mutations in various coronavirus variants, including the AY.4.2, in the spike protein (part of the virus’ outer surface which they use to penetrate the host cells) are Y145H and A222V.

What Do the Experts Have to Say on AY.4.2 Variant?

Though there is not enough evidence and peer-reviewed studies on this variant based on the type of mutations in the AY.4.2 variant experts say that this variant should not be as deadly as the Alpha and Delta variants. It is currently under investigation, and the World Health Organization, too, has not categorized this strain under any of its variants, such as the variant of interest, concern, and variant under investigation. While the Alpha and Delta variants were up to 50 and 60 % transmissible, the AY.4.2 variant is thought to be up to 10% transmissible. At this stage, no definitive statements could be made as the variant is under study. Experts are closely monitoring the variant.

What Parts of the World Have the AY.4.2 Variant?

Countries such as the United Kingdom, the United States, China, Russia, and recently India have observed a gradual increase in COVID cases caused by this strain. It has to be noted that in Denmark, the new AY.4.2 infections have decently reduced. Such a trend might give optimistic hope, but the steady growth in the number of affected cases cannot be ignored.

Is the AY.4.2 Variant Concerning?

Whether or not the mutations offer an advantage to this variant is unclear. They are under close monitoring. Initially, the variant was identified in September 2021 in the United Kingdom, but it is believed that its advent would have occurred in June 2021. Lately, in India, fresh COVID cases caused by the AY.4.2 are emerging in the states of Karnataka, Kerala, Andhra Pradesh, Telangana, and Kashmir. Since it has not gained any position in the variants categories of the WHO as of now, it is regarded to be not as deadly as the Delta variant. But with time, the real face of this variant would be exposed.

Also, super spreader events, gatherings, shows, etc., can contribute to rising COVID cases caused by the AY.4.2 strain.

Does the AY.4.2 Variant Evade Vaccine Protection?

At this stage, experts have mixed responses. However, they believe that this strain is marginally infectious but is not likely to become a dominant strain and that soon it would drop off the watch list. In contrast, the Y145H mutation of this strain is believed to have the possibility to evade immunity. Whether or not these evade vaccine-induced immunity is too soon to decide.

Are Vaccines Protective Against the SARS-CoV-2 Variants?

Vaccines offer better protection against COVID caused by all variants of coronavirus. The deadly variant Delta was found to escape the vaccine-induced immunity to some extent but still worked wonders. Several coronavirus variants evolve with time, challenging the efficacy of the vaccines. No vaccine is 100% effective and without any side effects. But the possibility that vaccines fail or vaccines become life-threatening is negligible, as with every other medicine or vaccine in the market. By getting fully vaccinated, you can fight this pandemic like a warrior.

Getting vaccinated does not prevent you from acquiring COVID, but it reduces the severity of symptoms and the need for hospitalization. It also reduces post-COVID complications.

Should I Still Wear a Mask?

Wearing masks, practicing social distancing, and hand sanitation is still mandatory for your and everyone’s benefit. By getting vaccinated and following these COVID control protocols, you greatly reduce the virus’ transmission and mutation. That is why global health organizations have been continuously stressing these protocols. The world is still in the process of fully getting vaccinated.


There is no wonder if another variant emerges next week. Until we all get vaccinated and follow the COVID control protocols strictly, the media will keep updating the daily surge in COVID cases and the new variant entry of the week. The third wave is expected, but our expectations can be made unrealistic by following the COVID control protocols. It is too early to panic and decide on the deadliness of the AY.4.2 strain, but it is not too late to get vaccinated.

Article Resources

Last reviewed at:
03 Nov 2021  -  4 min read




Comprehensive Medical Second Opinion.Submit your Case

Popular Articles Most Popular Articles

Do you have a question on Ay.4.2 Delta Variant or ?

Ask a Doctor Online

* guaranteed answer within 4 hours.

Disclaimer: No content published on this website is intended to be a substitute for professional medical diagnosis, advice or treatment by a trained physician. Seek advice from your physician or other qualified healthcare providers with questions you may have regarding your symptoms and medical condition for a complete medical diagnosis. Do not delay or disregard seeking professional medical advice because of something you have read on this website. Read our Editorial Process to know how we create content for health articles and queries.