Oxford-AstraZeneca vaccine effective against B.1.1.7 SARS-CoV-2 variant

By Angela Betsaida B. Laguipo, BSNMar 31 2021

The coronavirus disease (COVID-19) pandemic continues to spread globally, with new variants emerging. One of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants is the B.1.1.7 or U.K. variant. It is still unclear if the developed vaccines can protect against new emerging variants.

Now, researchers at the COVID-19 Genomics United Kingdom Consortium, the AMPHEUS Project, and the Oxford COVID-19 Vaccine Trial Group released the results of their exploratory analysis of a randomized controlled trial of the ChAdOx1 nCoV-19 (AZD1222) vaccine against the SARS-CoV-2 variant of concern 202012/01 or the B.1.1.7 variant.

Published in The Lancet, the study explores if the Oxford-AstraZeneca vaccine works well in protecting against the B.1.1.7 variant, otherwise known as the U.K. variant.

The researchers found that the adenoviral vector vaccine, ChAdOx1 nCoV-19 (AZD1222), exhibited reduced neutralization activity against the SARS-CoV-2 U.K. variant, which may affect the current vaccination efforts of multiple countries.

However, the vaccine helped protect against symptomatic disease caused by the novel variant.

Study: Efficacy of ChAdOx1 nCoV-19 (AZD1222) vaccine against SARS-CoV-2 variant of concern 202012/01 (B.1.1.7): an exploratory analysis of a randomised controlled trial. Image Credit: Krummerchen / Shutterstock

Study background

The COVID-19 pandemic has caused over 128 million cases and 2.81 million deaths worldwide. Vaccinating a majority of the population is crucial to attaining herd immunity and curb the coronavirus pandemic.

To date, many countries have rolled out their vaccination drives, which started among health care workers and front liners. Though vaccine platforms differ, most use the surface spike glycoprotein of SARS-CoV-2 as the key antigenic target for producing neutralizing antibodies and T cells.

Many vaccines have received Emergency Use Authorization approvals from the Food and Drug Administration (FDA) and regulatory bodies. Vaccine rollouts started in December 2020, providing hope that inoculating populations can end the pandemic.

However, in December 2020, the U.K. reported the emergence of a new variant, called the B.1.1.7 variant, which may cause increased transmissibility.

In the current study, the researchers aimed to determine if the Oxford-AstraZeneca vaccine can protect against the new strain of SARS-CoV-2, too.

The study

To arrive at the study findings, the researchers enrolled volunteers who are more than 18 years old. The participants were enrolled in the phase 2/3 vaccine efficacy studies in the U.K. and were randomly assigned to receive the ChAdOx1 nCoV-19 or a meningococcal conjugate control vaccine.

The team collected upper airway swabs weekly and if they developed COVID-19 symptoms, including fever, cough, shortness of breath, and loss of smell or taste. The swabs underwent testing using a nucleic acid amplification test (NAAT) for SARS-CoV-2, and positive samples were sequenced using the COVID-19 Genomics U.K. consortium.

A live-virus microneutralization assay against the U.K. variant was performed to measure the participants' neutralizing antibody responses.

The efficacy analysis included symptomatic COVID-19 in seronegative individuals with a NAAT positive swab more than 14 days after a second vaccine dose. The team analyzed the study participants according to the vaccine received.

The study findings showed that of the 8,534 participants in the primary efficacy group, 520 participants developed COVID-19. About 1,466 NAAT-positive nose and throat swabs were collected from the participants. Of these, 401 swabs were sequenced, finding that the laboratory virus neutralization activity was lower against the U.K. variant

Further, the team found that the clinical efficacy against symptomatic NAAT positive infection was 70.4 percent for B.1.1.7 and 81.5 percent for non-B.1.1.7 lineages.

Though there is reduced neutralization activity, the vaccine protected against symptomatic disease caused by the B.1.1.7 lineage, hence, vaccination with the Oxford-AstraZeneca vaccine resulted in a reduction in the duration of shedding and viral load, which may reduce viral transmission.

"ChAdOx1 nCoV-19 showed reduced neutralization activity against the B.1.1.7 variant compared with a non-B.1.1.7 variant in vitro, but the vaccine showed efficacy against the B.1.1.7 variant of SARS-CoV-2," the team concluded in the study.

This study is registered with ClinicalTrials.gov, NCT04400838, and ISRCTN, 15281137.

Increasing COVID-19 cases

The United States reports the highest number of cases, reaching over 30 million infections and over 552,000 deaths. Brazil and India report 12.74 million and 12.14 million cases, respectively. France, Russia, and the United Kingdom report 4.7 million, 4.49 million, and 4.35 million cases, respectively.