COVID-19 Updates, From New Highly Transmissible Variants to Vaccine Mixing Research

Written by Josephine Chen '24
Edited by Saradha Miriyala '23

Despite the emerging availability of vaccines for COVID-19, people are still not completely safe. Scientists have discovered several variants and mutations of SARS-Co-V-2 that are rapidly spreading in the United Kingdom and South Africa [1]. These variants have the potential to reduce the efficacy of the newly developed vaccines and the natural immune response of those who have recovered from the virus. 

The B.1.1.7 variant that was originally discovered in the United Kingdom is 50% more infectious than other variants [1]. In order for the person to be infected with the coronavirus, the virus needs to pass the cell membrane [2]. This variant has eight changes in its spike protein, which attaches and fuses itself to the human cell membrane to regulate entrance into the body [1, 2]. The 501Y.V2 variant that originates from South Africa can have nine changes in the spike protein. Thus, with so many alterations to the virus proteins, it is difficult for the antibodies of the immune system to identify the virus once it enters the body [3]. Researchers have found that people infected with the B.1.1.7 variant of the virus had more SARS-Co-V-2 viral loads in their body [4]. Viral loads are the amount of virus in the patient’s blood, and higher viral loads are associated with increased severity of the illness and a higher transmission rate [5]. One study has shown that viral load corresponds to mortality rate. The mortality rate for patients with a high viral load was 38.8% in comparison to the 15.3% mortality rate for patients with a low viral load [6]. 

Patients recovered from the virus develop an immune response, but this response is weaker against newer versions of the virus. A study took antibody serums from patients who recovered from COVID-19 and found that these antibody samples are less effective in combating the 501Y.V2 variant compared to previous varieties of the virus. The immune response was inadequate [3]. 

Although this variant can weaken the developed immune response, its effect on the reaction evoked by the vaccine is still unclear. Even if the antibodies are less able to fight the virus, the vaccines can stimulate the production of numerous antibodies that locate different regions on the spike protein [3]. Also, it is still highly likely that the behavior of T cells, or immune cells that destroy the virus, will remain unaffected by the variant [7]. Further research is needed to determine the impact of these variants on the vaccines’ effectiveness. 

With the discovery of more variants, researchers are currently testing methods to improve the efficacy of the vaccines. One idea that is being researched is whether mixing two vaccines would increase the immune response in our bodies. The two vaccines that are currently being administered, Pfizer and Moderna, are always given in two doses: the primary and secondary dose. The primary dose establishes the initial protection, while the secondary shot triggers the memory cells of the immune system and increases their responses [8]. Researchers are aiming to use one shot of a vaccine carrying the weakened coronavirus gene and a second shot of the Pfizer vaccine, which uses RNA to induce a reaction [9]. Although this study has yet to be conducted on humans, this idea has been applied to mice models. It was concluded that the mice who received the heterologous vaccination process had better T cell responses than those who only received one type of vaccine [10]. 

More studies need to be conducted in order to fully maximize the potential of the current vaccines available to us. With the prevalence of COVID-19 variants and mutants, it is now more imperative than ever that we all socially distance and wear a mask when outside. 

Works Cited
[1] Callaway E. Could new COVID variants undermine vaccines? Labs scramble to find out. Nature. 2021 Jan 7;589(7841):177–8.

[2] Bosch BJ, van der Zee R, de Haan CAM, Rottier PJM. The Coronavirus Spike Protein Is a Class I Virus Fusion Protein: Structural and Functional Characterization of the Fusion Core Complex. J Virol. 2003 Aug 15;77(16):8801.

[3] Callaway E. Fast-spreading COVID variant can elude immune responses. Nature. 2021 Jan 21;589(7843):500–1.

[4] Golubchik T, Lythgoe KA, Hall M, Ferretti L, Fryer HR, MacIntyre-Cockett G, et al. Early analysis of a potential link between viral load and the N501Y mutation in the SARS-COV-2 spike protein. medRxiv. 2021 Jan 15;2021.01.12.20249080.

[5] SARS-CoV-2 viral load predicts COVID-19 mortality - The Lancet Respiratory Medicine [Internet]. [cited 2021 Feb 26]. Available from: https://www.thelancet.com/journals/lanres/article/PIIS2213-2600(20)30354-4/fulltext

[6] Westblade LF, Brar G, Pinheiro LC, Paidoussis D, Rajan M, Martin P, et al. SARS-CoV-2 Viral Load Predicts Mortality in Patients with and without Cancer Who Are Hospitalized with COVID-19. Cancer Cell. 2020 Nov 9;38(5):661-671.e2.

[7] How ‘killer’ T cells could boost COVID immunity in face of new variants [Internet]. [cited 2021 Feb 26]. Available from: https://www.nature.com/articles/d41586-021-00367-7

[8] Understanding How COVID-19 Vaccines Work | CDC [Internet]. [cited 2021 Feb 26]. Available from: https://www.cdc.gov/coronavirus/2019-ncov/vaccines/different-vaccines/how-they-work.html

[9] Heterologous vaccination regimens with self-amplifying RNA and Adenoviral COVID vaccines induce superior immune responses than single dose vaccine regimens in mice | bioRxiv [Internet]. [cited 2021 Feb 26]. Available from: https://www.biorxiv.org/content/10.1101/2021.01.28.428665v1

[10] Could mixing COVID vaccines boost immune response? [Internet]. [cited 2021 Feb 26]. Available from: https://www.nature.com/articles/d41586-021-00315-5

[Image Citation] COVID-19: What is the new variant of coronavirus? [Internet]. BBC Science Focus Magazine. [cited 2021 Feb 26]. Available from: https://www.sciencefocus.com/news/covid-19-what-is-the-new-variant-of-coronavirus/