By Victoria Sahadevan Fossland, MD

Information and data regarding what is known about variant strains of the COVID-19 virus continue to evolve. The information contained here is current as of May 3, 2021.

The significant rise in COVID-19 cases in India over the last several weeks has raised concerns in the US and around the world about whether the vaccines currently being administered can deter infection caused by new strains of the virus.1 Two key questions on many people’s minds are 1) What do we need to know about variant strains of COVID-19? and 2) Are we protected if we have been vaccinated?

What is a variant COVID-19 strain?
First, let’s consider what we mean by a variant strain of the virus. In general, viruses reproduce constantly within infected hosts.2,3 During viral reproduction, also referred to as replication, genetic errors occur naturally. Replication errors produce strains of the virus that have mutations in their DNA, which is why they are called variant strains.4 Some mutations allow variant strains to survive when the wild type (original) strain dies off due to a host’s immune system response or as the result of treatment deterring viral replication and survival.3-5 Still other mutations can help new strains escape detection by the host’s immune system or can help the virus spread more easily, meaning it is more transmissible.4,6

How do mutations in COVID-19 variants affect how the virus spreads?
COVID-19 is a coronavirus. The crown-like spikes on its outer surface provide a target for vaccines. Mutations can modify these spikes, and as a result, affect how the virus spreads and what happens to people who are infected with it.4 Some variants appear to survive better and spread more quickly than others.6

What do we know about COVID-19 variants?
Several COVID-19 variants have been identified in infected patients around the world. The COVID-19 virus has demonstrated different patterns of spread between areas and even within countries.7

Accordingly, specific variants have dominated different regions in India. B1617 and B117 appear to be the 2 most dominant strains.7 Here’s a brief summary of the major COVID-19 variant strains identified to date that seem to spread more easily and quickly than others.1


  • Also known as the UK variant because it was initially detected in the United Kingdom10
  • Accounts for infection spikes in some parts of India11
  • Believed present in the US as early as October 202012
  • First identified in the US in December 20204


  • Initially identified in early January 2021 in travelers from Brazil during routine airport screening in Japan4
  • Carries multiple mutations that appear to have carried over from an earlier variant, B11289
  • First detected in the US in January 20214


  • Emerged in South Africa in December 20204,10
  • First identified in the US at the end of January 20214

B1427 and B1429

  • Classified by the World Health Organization (WHO) as “variants of concern” in March 20214
  • First identified in the US in February 20214


  • First detected in India in December 20207,11
  • An earlier version of the variant was spotted in India as early as October 202011
  • Has been reported in 17 countries11
  • Contains 2 key mutations to the outer “spike” portion of the virus, which attaches to human cells11
  • A WHO “variant of interest” that may have mutations making the virus more transmissible, be able to cause more severe forms of disease, or be able to evade vaccine-induced immunity11
  • Reported in the US as of April 202113


  • First identified in Brazil and Japan1
  • Carries many of the same mutations as variant P1, which confer higher transmissibility8
  • Not yet reported in the US9

Do people who received a COVID-19 vaccine need to worry?
A number of studies have provided insight into the relationship between COVID-19 genetic variability and an individual’s immune response.6 Studies suggest the antibodies a person generates through vaccination with currently authorized vaccines can recognize the variants of concern.4

While it’s possible that over time continued COVID-19 mutations may make it more difficult for vaccinated people to overcome infection with variant strains, it’s important to recognize that so far, no evidence shows that genetic variability has rendered the current vaccines less effective.6

It’s also important to note that a single dose of COVID-19 vaccine has shown the potential to cut household transmission by half.7

Fortunately, when compared to other infectious viruses, COVID-19 has a relatively low mutation rate.6 Moreover, gene-sequencing data in India is sparse, and many cases have been driven by the UK and South African variants, making it difficult to assess whether an “escape variant” is overpowering prior immunity.11

B1617 contains several clinically important mutations that have been observed in other variants. These mutations can lead to increased transmissibility, reduced neutralization by some antibody treatments, and a moderate reduction in the blood of people who have been vaccinated.7

However, there is no evidence that B1617 and related variants cause more severe disease or render the vaccines currently deployed less effective.11 Current vaccines target multiple regions of the COVID-19 spike protein, suggesting a limited effect of viral mutations on a host’s immune response.6

How do we prepare for future COVID strains?
Vaccine developers are already engineering the next generation of COVID vaccines, some of which address the temperature sensitivity and administration challenges presented by current vaccines.1 Because of the way vaccines are designed, it’s possible to periodically reformulate them to better match predominantly circulating strains.6 A vaccine designed and produced in India is already able to neutralize the B1617 variant that is ravaging parts of the country.7,11

Although the first wave of vaccines focused on targeting COVID-19’s spike protein, almost 60 new COVID-19 vaccines are under investigation worldwide, most of which use novel mechanisms to deter viral replication.1 Next-generation vaccines aim to induce immunity that protects across strains and broadens the range of viral components that provoke an immune response. 

Booster shots directed at the B1351 variant are under development, as are vaccines that may stimulate mucosal immunity, protect with a single dose, remain stable at room temperature, or be administered more easily, such as in a nasal spray or pill form.1

Let’s not forget the overall effectiveness of any vaccine depends on maximizing the proportion of the population receiving it. Reducing the number of susceptible individuals provides fewer opportunities for COVID-19 to replicate, mutate, and spread.6

Moving forward, data obtained as more of the world’s population becomes vaccinated will help identify whether next-generation COVID-19 vaccines will be needed at all.1


  1. Sheridan C. COVID innovations: vaccines for variants, drone deliveries, print-your-own shots, and more. Scientific American. April 30, 2021. Accessed April 30, 2021.
  2. Ryu WS. Virus life cycle. Molecular Virology of Human Pathogenic Viruses. 2017;31-45. doi:10.1016/B978-0-12-800838-6.00003-5
  3. Viruses and evolution. The History of Vaccines. January 10, 2018. Accessed May 2, 2021.
  4. About variants of the virus that causes COVID-19. Centers for Disease Control and Prevention. April 2, 2021. Accessed April 30, 2021.
  5. Sanjuan R, Domingo-Calap P. Mechanisms of viral mutation. Cell Mol Life Sci. 2016;73(23):4433-4448. doi:10.1007/s00018-016-2299-6
  6. Williams TC, Burgers WA. SARS-CoV-2 evolution and vaccines: cause for concern? Lancet Resp Med.2021;9(4):333-335. doi:10.1016/S2213-2600(21)00075-8
  7. Schnirring L. India’s surge leads to further global COVID rise as role of variants probed. Center for Infectious Disease Research and Policy. April 28, 2021. Accessed April 30, 2021.
  8. COVID-19 scan for Mar 03, 2021. Center for Infectious Disease Research and Policy. March 3, 2021. Accessed May 5, 2021.
  9. COVID data tracker: variant proportions 1/17/21-4/10/21. CDC. Accessed May 5, 2021.
  10. Kelland K. Risk from virus variants remains after first Pfizer COVID-19 vaccine, UK study finds. Reuters. April 30, 2021. Accessed April 30, 2021.
  11. Explainer: what we know about the Indian variant as coronavirus sweeps South Asia. Reuters. April 29, 2021. Accessed April 30, 2021.
  12. Undetected coronavirus variant was in at least 15 countries before its discovery. UT News. April 1, 2021. Accessed May 5, 2021.
  13. Sainz A. COVID-19 variant found in India reported in Memphis. AP. April 29, 2021. Accessed May 5, 2021.


Victoria Sahadevan Fossland, MD, is a general surgeon and medical writer of print-based, interactive learning, and multimedia projects. She writes clinical education pieces about a wide variety of diseases. Her work explains disease pathophysiology, treatment, clinical trial research details, and concerns that can arise from both physician and patient perspectives. Victoria has used her expertise in distilling medical knowledge into readily comprehensible and accessible learning solutions to write many valuable communications, learning modules, and workshops for Encompass, including the script for an award-winning video.

Leave a Reply